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308 subsonic
I'll jump right in here and share my success with .308 subsonics:
I begin with a starting load of Accurate 5744 powder. I then work backwards until I reach the subsonic speed I desire. I will chronograph each load for a particular gun and write it down in my log book. In my 308 Encore barrel (23 inch, 1:8 twist) I hit a good subsonic velocity at about 12gr of powder using a 220gr Sierra HPBT match bullet. I have been using magnum primers and a good crimp on the bullet but this is not always necessary or desired. My accuracy in this barrel with 220gr subsonics has easily been MOA at 100 yards. The velocity spread also has been low. I find that each barrel will be a little different in resistance so one load recipe will not always work in a different barrel. My bolt gun (18 inch, 1:10 twist) was way off of a good subsonic speed with the same load that worked great in my Encore. I believe that this critical subsonic window is why there are not very many over the counter 308 subsonic loads. What may work great in one gun may be too slow in another etc.... I don't like to guess a subsonic load because that is where you may end up with a stuck bullet in your bore. I always work backwards from the published starting load a little at a time until I reach a good subsonic speed. Don't use just any powder for loading subsonics in rifle size cases. There is dangers associated with using low volumes of slow powders. Accurate 5744 is one powder that I keep coming back to because it just works. It is not effected by low charges in a case. In fact, the person I talked to over at Accurate powder tells me that it was designed to not be position sensitive with low charges in relatively big cases. It also has a higher nitroglycerin content for easy ignition. Another powder to try is IMR SR4759. They sell it in the metal IMR cans but you only get a 1/2 pound since it is so bulkey. It is in the same class as Accurate 5744 but is a more bulkey powder. Fast pistol powders will work, but there is a danger of a double charge of powder causing more pressure than is safe. I stay away from them for this reason. With 5744 and 4759, you can visually inspect the charged cases before seating a bullet and easily see if there is a possible double charge. A double charge of these (when measuring for subsonic loads) will not be over the maximum load listed in the manuals. If all you have is a 1:10 twist barrel, you will have problems with accuracy if you go heavier than a 180-200gr bullet. I would suggest that 180gr bullets be max for the slower 1:10 twist barrels. If you use a bullet that is too heavy for your twist, you may have a hard time hitting the target at all. They will flop around in the air like a poorly thrown football and you can actually hear them wobbling through the air down range. |
JF,
I know you mentioned only using 180-200gr bullets in a 1 in 10" twist, but what about the Hornady RN 220gr flat base bullets? The OAL of the 220gr bullet is about the same as a 175gr Sierra Match King, and I've used those subsonically without keyholes nor baffle strikes. The fact that they have a flat base rather than a boat tail should help in their stability in a 1 in 10" twist. I haven't tried them yet, but just thinking out loud because I was looking and comparing the two bullets at the reloading shop last week. I've always used bulky fast pistol powders like Unique and Red Dot. Red Dot works fine in the winter, but is VERY temp sensitive, and oftentimes goes supersonic on me in the summer. How much case volume does the two powders you mentioned take up (grain for grain) compared to flake powders like Unique and Red Dot? I was thinking of trying VVN310 or Titegroup next (supposedly case position insensitive). What do you think? Thanks! |
I haven't been able to get good subsonic accuracy with the Hornady 220 round nose in my Whisper or my 308. Both of them are 1:8 twist barrels. I wouldn't think that a 1:10 twist would make their accuracy any better. Yes they are shorter but the driving area or something does not seem to like the slow speed or lower pressures. This Saturday I decided to give up on them after repeated testing in my Whisper (I was only getting 3 to 4 inch 100 yard groups). Sierra makes a heavy round nose bullet also but I haven't tried it yet.
I don't know the exact volume percent that 5744 and 4759 gives me in a 308 size case. I would guess that it is about 1/3 to 2/5 of the case or so. It is substantially more than the fast pistol powders. Some powders are more position sensitive in the case than others when lower volume charges are used. Tipping the barrel down or up before chronographing your loads will tell you this. The fast pistol powders, in my experience, seem to suffer from this more than 5744 and 4759 do. |
JF,
Thanks for your thoughts. What suppressor are you using? I'm using a Thundertrap on a 16" Savage barrel. You seem to be interested in getting maximum precision and consistency. I like those attributes too, but I must admit I'm seeking ultimate sound suppression. I would have to think that the larger charge weight of your 5744 load (~12 grains as opposed to ~8.5 grains of Unique or Red Dot) would make it slightly louder because the suppressor has more gas work. Did you find this to be the case? Also, since I'm only using a 16" barrel, I figured the fast pistol powders would be fully burned and easier to suppress than the slower 5744. What do you think? Am I barking up the wrong tree? I'm trying to disagree with you. I'm trying to learn something and hopefully find a more effective load than the one I've been using. If your load is safer, more precise, and JUST AS QUIET as the ones I've been using, then I owe you a huge debt of gratitude for sharing your success with us. |
I use an HTG suppressor. It is little known and relatively new on the market but compares better than some of the more popular models for its noise reduction quality.
Funny you should mention maximum quiet and precision. Those are my two primary objectives too! Yes, the less powder volume you burn the quieter things can be. But there are some limitations. My 308 is a 23 inch, 1:8 twist, Virgin Valley Encore barrel. And yes the faster light charges do produce less muzzleblast and noise. But I have not seen a huge deal of difference in noise between 5477 and the faster pistol powders out of the 23 inch barrel. Your shorter barrel might make more of a difference. In my 16 inch 300 Whisper Contender barrel, there is a very noticeable difference in noise when comparing H110 with Winchester 231 in subsonic loads. Even with no suppressor installed, I can still hear quiet a difference between the two. I have access to some expensive precision sound testing equipment and am trying to test this out this weekend if I can meet up with the guy that has it. If I do, I'll post the results here. The last time I tested my 300 Whisper with sound testing equipment, I brought along my RWS pellet gun. The pellet gun registered in the 113 to 115 decible range. My suppressed Whisper (using H110 powder) was very close to that. With these new 231 loads I have been trying, I fully expect the noise to actually register below the sound signature of my spring piston pellet gun. Like I said, I'll post these and the sound results of the 308 sub loads as soon as I can get this tested. |
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That sounds fascinating and I'll eagerly be awaiting any results you have! When you were testing before, were you using the Larson Davis 800B sound meter with a 1/4" mic, with the muzzle 1 meter to the right of the mic? I ask because 113-115dB actually sounds a little low for an adult air rifle. BTW, would you tell me more about this HTG suppressor? I've been looking for an upgrade. |
OK, I did some research and see that HTG stands for High Tech Gunworks in Boise. Is that Jim Ryan's company? There seems to be alot of good suppressor mfgs in that area! I'd still like to hear more about the suppressor!
Thanks |
HTG - Boise, Idaho-208-323-7674. His suppressors are killer from a design standpoint. The HTG suppressors get about 33+ decible reduction from his 22/223 and 30 caliber models. He has some 9mm and 40SW models that will let the pistol cycle. Pretty cool! I'd love to get one of them.
I have one of the HTG 22/223 sups and it is real quiet when I put it on my bolt 22 rifle and feed it subsonic 22s. It is a hoot to use it for rodent hunting or animal control applications. About all you hear is the bullet impact. I can also stick it on my 223 AR and shoot without all that noise discomfort at my shooting range. Yes to the Larson & Davis equipment and testing methods but I don't know the model number. I seem to recall from my past readings on some pellet gun website that the RWS spring piston pellets rifles are a little quieter than some of the others out there. I've never compared different pellet guns side by side though. I was simply trying to see if my suppressed 300 Whisper was near the sound reading of a pellet rifle. It was. |
JF,
A few more questions for you (where were you 4 yrs ago when I started messing with suppressors?) 1) What's your suppressor guy's name? 2) Is there any sound difference between your subsonic 308s and your 300 Whisper (both suppressed)? 3) Would you mind sharing some of the dB numbers of different gun/suppressors you tested, including the .22s and .223s? 4) What's different about the design of HTG suppressors? Baffle design? Materials? I'm thinking of another .30 cal can (was considering SWR, SRT, and Jet), and now the HTG has caught my attention. |
I said I would post some sound testing results so here it is. But let me say from the start that I do not claim to be a sound testing expert. Take this info for what it is and please don't bash my results. If you can use this info - great.
I started by testing 220 subsonic loads in my 300Whisper. If I switch from H110 powder to the much faster Winchester 231 powder, I was able to drop the sound by about 3 decibels. When you consider that to double a sound on the decibel scale you need to increase it by 3 dB, I think this is significant. I was asked if my subsonic 308 loads were the same noise level as my whisper loads. No, the 308 was louder by about 3 to 4 decibels. But it is comparing apples to oranges I believe. If I had the same gun and the same type of barrel, powder etc, the results might be differrent. unsuppressed 308 subsonic (5744 load) = about 154dB unsuppressed 308 supersonic (4064 load) = about 166dB unsuppressed 300 Whisper subsonic (H110 load) =about 151dB unsuppressed 300Whisper subsonic (W231 load)= about 148dB unsuppressed 300Whisper supersonic (H110 load) = about 157dB Please note: I did not shoot tons of each load in an effort to get the most accurate averages possible. I only shot a few of each to get a general idea of the readings. |
That's interesting data. Thanks!
So when you were testing, you were using the 23" bbl for the .308 and the 16" bbl for the Whisper? If so, that tells me that the Whisper is INHERENTLY a quieter round than subsonic .308, even though they are pushing the same bullet at the same velocity. This is fascinating. I need to stop wasting my time with making subsonic .308s, and get myself a Whisper bbl for my Savage!!! |
That is what I would recommend... I talked w/EBR and found thier powder is better. I do NOT recomend TTI armory.
I have a 20" savage w/an AWC thundertrap and found EBR to be the best. I am, however, about to start shooing 7.62x39 jackhammer as soon as I can find a twist rate I want to shoot the heavy load. Here are some details... http://www.ebr-inc.net/LowbandAmmoDetail.asp?id=3 I want .300 whisper, but her of so many problems that I am affriad to try it. |
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Looking for low volume .308 brass
I was told someone made .308 brass with much thicker walls around the web/base so the volume was low. I can't find it.
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Well, I am just going to have to bump this up to the top. I have started
looking into some subsonic 308 projects as well now. I was hoping to see as much on the 308 as there is on the whisper here :cool: Just kidding. I have found a little tidbit that may be helpful to fill the case. The product is Pufflon http://www.pufflon.com/ Looks like the Unique at up to 8.5grn with 150grn bullets is one that I have heard of but not tried, yet. Was told to start a little lower and work up to speed. Also have heard that Mullins Ammunition has the info but would probably not let any out. Has anyone heard this or know anyone over there?? Lets see if we can get this thing going again :bangin: |
I heard about pufflon.
My question is how do you make it work in a silencer with out filling your silencer with that "magic stuff"? :D ND |
Roger on the puff-lon. That was my question to them. :cool:
Flash cotton seems to be a better choice, but it may effect the charge a little. I talked to one gentleman who is using it and it works quite well. On the other hand, one of the main "dudes" does not use any filler at all. |
In france, most experienced subsonic shooters,do not recommend to use any filler.
ND |
link on another website 'bout 308 subsonic loads
http://www.silencertests.com/silence...opic.php?t=169 Basically using Trailboss powder - very bulky working very well for them. Debo's Results- 200gr Speer Spitzer SP, 11.7gr Trailboss, CCI250 (Large Rifle Magnum) primers, Federal GMM brass, 70 degrees- Shot through 20" Douglas SS bbl, 1 in 10 twist, SRT Shadow suppressor. MV for three shots with 11.7 gr was 1031 1029 1061 This was preleminary. Going to load up some and head to the range later this week hopefully. Scott- yes they stayed subsonic. I worked up from 9gr (604fps), 10gr (824fps), 11gr (986fps), 11.5gr (1009fps), 11.7gr (1031,1029,1061fps). Debo also this... Quote: If anyone would sacrifice a commercial subsonic round, it would be interesting if they'd dismantle one (safely, of course), and see just what kind of volume the powder charge actually displaces. Also, if the flash hole appears to be larger than normal. Reply I already did: EBR 180gr subsonic has some strange powder I have never seen in it. I don't remember the exact load density but there is lots of room for the powder to slosh back and forth inside. The flash-hole is not enlarged. Lapua 200ge subsonic has what looks like a N310 but with smaller granules which would indicate it is even faster burning than N310. The flash-hole is not enlarged. End Quote |
Hey guys,
Lurking around on this forum and saw my name mentioned :nanabang: I am still working on the subsonic .308 load. The 11.7gr ended up being very inconsistant with velocity. My latest is 200gr Speer Spitzer, 12.3gr Trailboss, CCI magnum primers, Federal brass with flashhole drilled out larger. It seems to be working pretty well giving me 1030 to 1070fps or so and 1.5MOA groups. I feel like I have to test it a little more but I am going to make a nice writeup on Silencertests and I will cross post here and Snipershide. Debo |
I have a SR-25 sniper rifle with a 24" 1-10 twist barrel. I use a Lauer Weapons .30 cal suppreser with great results. I use the military M118 173gr ammo. I remove the factory powder and reload them with 45.5gr of Varget for long range shooting. I use Varget for it is almost impervious to temperature with extreme accuracy, 1/4 MOA at 100m. For missions that require silence I reload the M118 with 8gr of Titegroup. This shoots at 1062fps at 28 degrees F and neted 3/4 MOA at 100m. This set up is very quiet and very accurate out to 400m.
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Artful, you seem to be knowledgable on this matter.
I'm looking for some direction from yourself or any other reader of this posting. I have a DPMS 308 Long Range Rifle. The barrel is 1 in 10 twist. I have a Gemtech TPRS Sup. I am researching where to start in developing a sub-sonic round for my set-up. I have read so many opinion in the last few days that my brain hurts. I have done alittle reloading myself but mostly pistol ammo and 22-250's. In my search, there seems to be a consensous that underloading (to much air) or using fillers (cotton fibers) is a bad idea. I did find an article where the auther suggested the use of dacron. (pillow stuffing) and claimed that it incenterated completely without clogging. I'm not sure why someone would like to take a chance and clog the baffles in a Sup...so for safety reasons, I have decided to start out using low volume 308 cases. I don't know how the receipts will differ between pressures. For example one of my questions would be: Would the pressures be the same if I put 12 grains in an reduced volume case with less air vs. 12 grains in a standard underloaded case with more air. I'm looking for a safe starting point...Bullet weight?, Powder type?, Charge amount?, Standard/Magnum Primer. Any advise....? And even a more important question, will it even be possible to get this AR-308 to even cycle rounds? If not, are there any safety concerns if I use this rifle as a single shot. Meaning, if there is not enough blow back to cycle the next round, are there any side affects that will cause damage to the gas tube, bolt assembly, etc. if I were to manually feed it one at a time? |
Hi
New to this forum and a novice at reloading subsonic .308 so please forgive the basic questions. Looking to buy a .311 rcbs mould to cast my own and in the UK we are limited to which powders we can purchase. Currently we can purchase easily a french powder called Vectan SR9. Ok for supersonic etc. Apparently there are 2 weights of bullet moulds you can buy in rcbs 308 you can cast 93gr and 155gr approx, as you can gather I am learning and have more info to gather. The powder charge to be used I believe is in the region of 4grains so I would assume be careful of secondry detonation and I am sure you will have to use a case packer like cotton wool? I await any knowledge/ advise. Regards Adrian |
:grin: Have not been back here for a while, but here is where I am at
with the load. 9.2grn Unique, Sierra 180grn round nose, CCI large magnum primers. Cases fully prepped: trim, full length size, primer pocket uniformed and flash hole debur. They shoot good. No filler, though I did get some flash cotton and Pufflon. I have a few loaded that I moly coated and have "seasoned the barrel" Will be testing them and see what this does for the spread/speed/etc. I did notice that shooting from an elevated position as from blind, that the drop is noticeably less:eek: Good thing I shot a few from a similar position prior to dialing for the hunt. http://www.fototime.com/{1BE7871E-EA...D}/picture.JPG http://www.fototime.com/{3EA07833-C5...3}/picture.JPG The rounds punched through this hog at around 80 yds, no problem, but did not hit the spine solid dead center. There were a few fragments near the exit hole, so I am guessing that the bullet expaned fairly well. (pass through) |
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I have seen the reports of .308 case with reduced volume (either home made - JD Jones route with expoxy or machined from brass) and the same powder charge in lower volume contain will equate to higher pressure... RifleShooter Jan/Feb 06 issue and some of the other people Debo for example are experimenting with .308 are using bulkier powders in unreduced volume cases Hodgdon's Trail Boss seems to giving good results. As to Auto Rifle function with subsonic - possible in AR10 I don't have any experience with that platform - I do know it it possible with similar gas system in AR15 but it depends upon many things...Gas port size - location on the barrel - gas pressure at the port - length of barrel beyond the port - pressure curve of load used - ad nasium... If you use a slower burning powder which keep up the pressure curve and you have enough barrel length after the port (of course your suppressor should help with back pressure) it may be possible to have semi auto function - my first test if I were you would to be buy a commerical 180 or 200 subsonic load - take my can off and shoot to make sure it was stable if it was stable and functioning the action I would put the suppressor back on and see how it functioned. Then I would take a round apart and see what kind of powder (stick, ball etc) and how much it was loaded with so I could have some kind of idea to reverse engineer :wink: As to single shot function see if someone makes an adjustable gas tube or block or if a gunsmith offers a modification to your existing gas block. If you fire sub power loads the only down side I could see would be partial unlock of bolt with maybe some gas leakage into the action from tube/barrel (IE more clean up:frown:) As for fillers w/ suppressors I don't think I would want to use any with my cans - I have used fillers in fireforming cases and such but not with subsonic loads. |
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I hop that some of this may be helpfull for you. Artful is correct that if you don't have a modified gas system the bolt will not fully cycle, it will partly open, needing a lot more cleaning. I get between 15-20 rounds before I notice the bullets wont chamber as nice. If you send your upper to www.medeshafirearms.com they can instal an external bolt handle on your bolt carrier. This makes chambering your rounds a lot easyer than the T-handle. I had this done to my SR-25 just for subsonic ammo. I think it cost around $110. As far as a place to start for a load, I called Hodgdon (913-362-9455) they said to use 8gr Clays with 168gr Sierra Match and Magnum primers, no filler and Winchester Brass. I didn't have any Clays at the time but I did have a lot of Titegroup so I tried that with 8gr and it worked very well. I got some Clays and tried it, I found that I could not get the same accuracy with the Clays versus the Titegroup but the Clays was a bit more quiet. I found that useing 8gr of Titegroup with 173gr Military Match projectiles will produce sub MOA at 100m. I shot 20rds through my chrony today with a low of 1028fps and a high of 1062fps and an average of 1052fps. Temp was 48 degrees, humidity 40%, elevation 802ft. I also spoke with a rep from Lapua, (630-350-1116) for a good projectile for sub loads. They have a 200gr FMJBT product code (B416) that they make specific for sub loads. They said that in a 1x10 barrel if you load them with the base of the bullet forward that they will stabalize. I bought some of them but have not tried this yet. I will post as soon as I do, should be next week some time. Once again I hope that this is helpfull. |
200 grain Lapua sub load
I finaly got some of the Lapua B416s loaded and went to the range today. Over all length with the base of the bullet loaded forward is 2.474"
Temp was 42 deg. humidity 60% elevation 802ft. I loaded 14 bullets to start so I could find out what works. Starting point was 9.4gr tite group. 1st shot was 1200fps 2nd shot 1188fps. 9.2gr, 1st 1166fps 2nd 1128 9gr, 1st 1089fps 2nd 1103, 8.8gr, 1st 1083fps 2nd 1074 8.6gr, 1st 1019fps 2nd 1025 8.4gr, 1st 1035fps 2nd 996 8.2gr, 1st 986.9fps 2nd 989 Suprisingly none of these showed signs of tumbling at 25yrds. All punched a clean hole through a 1/4" particle board. The only problem that I ran into was the fact that with the flat base of the bullet forward I had to single load each round. They would not feed from the mag. I think that if I opened up the feed ramps than they might feed. Any suggestions on this would be wonderfull. I am going to load more up with 8.4, 8.5, and 8.6gr and go back to the range to get more data. I will load up 15 of each to get a good spread. Will post more when I get this done. Any suggestions would be great. |
bump, so I don't loose this thread
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great info, I can't wait to start developing subsonic .308 loads.
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Trailboss experiment 1
I've wanted to load some subsonic ammo for my .308's
I started with the Evil Black Rifles HK91 and FAL my buddy brought his PTR91 (hk91 clone) and we had some rounds to try out. These loads are not recommended and is only for information purposes. This is our day... All ammo loaded in Remington 308 case's w/ 163 grain Flat Base spirepoint pulled military surplus bullets fired by CCI 250 magnum primers. Weather 82 deg F - sunny, not much breeze... AAC Cyclone can 12 grains of Trailboss my HK fired 1096 fps and 1061 fps in clean barre and oiled barrel then put Hornady Oneshot Case sizing lube on bullet let dry - velocity 696.6! My Bud's PTR91 fired in clean and oiled barrel 1093 fps and 1071 fps and 986.8 fps then tried one with OneShot Hornaday case lube on the bullet 636.6 fps - tried another without OneShot on it 1024 fps 11.5 grains of Trailboss My HK91 962.6 fps and 1016 fps PRT91 994.9 fps and 829.7 fps my FAL w/ 21" barrel 845.6 fps and 915.3 fps added OneShot 781.5 fps and 811 fps cleaned and re-lubed barrels w/ CRC Power Lube 11 grains of TrailBoss My HK91 785.1 fps and 726.8 fps PTR 91 940.1 fps and 824.4 fps FAL 856.4 fps first shot, 657.6 fps second shot, 567.0 fps third shot and 726.1 fps final shot 10.5 grains of Trail Boss My HK91 636.7 fps and 762.5 fps PTR91 691.8 fps and 769 fps cleaned and lubed barrel on FAL w/ CRC Power Lube FAL 793.7 fps 758.9 fps nice bullet holes figured I'll put the can on to see what it sounds like - 514.8 fps bullet perfect KEYHOLE in target - tried to shoot another and bullet lodged in the barrel yes did get it out - pulling all the lighter powder charges Now keep in mind these where all individually weighed powder charges so they are as listed to with accuracy of the balance beam scale. Conclusions: redo test with slightly higher powder charges and only 2 ten's change in powder charge - That lubing the barrel doesn't keep you from sticking a bullet - That shooting the bullets with Hornady OneShot case lube significantly slows the bullets down. That somehow at very low velocity the addition of the suppressor caused the bullet velocity to be further retarded in the FAL - something I haven't seen with full power ammo. |
Artful interesting info. My test routine is to run an oil patch through then a dry one and fire a round. Then I start measuring the velocity and after 20 rounds I do the whole thing over. Your testing seems to confirm my rule of thumb that when the bullet drops below 750 fps you had best start looking for a stuck bullet or at least thats when they seem to start not popping out for me. Glad you could get the stuck one out. Couple of months ago I had to chop a sks because I wasn't so lucky but I got a nice parts rifle now.
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Trailboss experiment 3/15/2007 - Part Duex
I've wanted to load some subsonic ammo for my .308's, todays experiments concentrated on my Imbel FAL with it's 21 inch barrel. We had some more rounds to try out. These loads are not recommended and is only for information purposes. This is our day... :)
All ammo loaded in Remington 308 case's w/ 150 grain Hornady Flat Base spirepoint bullets fired by CCI 250 magnum primers. (a shorter bullet than the last bullets experimented with :wink: ) Weather 87 deg F - sunny, not much breeze... AAC Cyclone can Last time we had taken Suputin's advise and cleaned and lubed between groups of powder trials [http://members.shaw.ca/cronhelm/DevelopSubsonic.html], today we wanted to see if we could use the barrel without special preperation (which is how it would mostly likely be in the field). 13 grains of Trailboss All fed from the magazine... Can off - Grenade gas setting 1251, 1332 Can ON - Grenade gas setting 1309, 1367, 1340 Can ON - Semi-Auto Setting 1243, 1336, 1317 12.8 grains of Trailboss All Fed from the Magazine Can off - Grenade gas setting 1181, 1202 Can ON - Grenade gas setting 1097, 1313, 1334, 1313, 1338, 1333 12.6 grains of Trailboss All fed from the Magazine Can off - Grenade gas setting 1163, 1199, 1089 Can ON - Grenade gas setting 1142, 1277, 1293, 1158, 1317 Now we had noticed an unsettling velocity gap that had developed in some of the strings and we decided to take a side branch to see why there could be several hundred feet per second spread in these carefully weighed powder charges.... deduced that the angle that the charge was in the cartridge case was playing a part in the velocity changes so to test that theory, that we tried loading ammo into the rifle in different ways. The TILT UP method involves putting a cartridge in the chamber and then tapping the gun to settle the charge to the rear of the case then gently lowering the muzzle to the rifle rest and firing the charge. The other method of loading the charged cartridges, was done by laying the cartridge on top of the magazine leaving the rifle facing the target and hitting the bolt release, which will distribute the powder more or less evenly over the bottom of the case as the BOLT Rammed it home. first we just wanted to see if the up tilt was going to produce a difference 12.4 Grains of Trailboss Can off - Grenade gas Setting - up 929.2 , up 1079, up 1146 Can ON - Grenade gas setting - up 929.0, up 1016, Can ON - Grenade gas setting - bolt 1324, bolt 1311, Can ON - Grenade gas setting - up 1115 12.2 Grains of Trailboss Can off - Grenade gas setting - up 986.2, up 1120, up 1148, up 992.2 Can ON - Grenade gas setting - up 951.9, up 1117, up 1185, up 1145 12.0 Grains of Trailboss Can off - Grenade gas setting - up 956.1, up 960.0 Can ON - Grenade gas setting - up 1087, up 1141 Can ON - Grenade gas setting - bolt 1282, bolt 1281, bolt 1268, bolt 1247 11.8 Grains of Trailboss Can off - Grenade gas setting - up 950.6, up 1170 Can ON - Grenade gas setting - up 1024, up 1147 Can ON - Grenade gas setting - bolt 1261, bolt 1220, bolt 1232, bolt 1208 All holes in the paper target exhibited roundness with no tipping evident, but several times it was noticed a wide swing between impact area's with can on vs off and again between tilted and bolt loading but I would expect this with velocity veriations at these slower velocities. Now keep in mind these where all individually weighed powder charges so they are as listed to with accuracy of the balance beam scale. Conclusions: While lubing will help with subsonic loads, I'm not sure it's required. Not even the hottest load attempted to cycle the action. Evidently Trailboss is sensative to powder position (in fact moving the powder to the rear of the case seems to lower the velocity by several hundred feet per second with the same powder charge) While case loading density is about 1/2 the case, I'm not yet sold that Trailboss is the best choice for subsonic loading. |
I was hoping you would get more than a 50% density case loading because that is the problem with fast pistol powders. As the powder shifts around the burn varies and so does the velocity but unfortunately as far as I know Trailboss is the most dense that is of the right speed and has a volume of .217cc per grain. Keep in mind if you allow the bolt to slam it home rather than hand chamber it all of the powder ends up around the bullet. Don't know if you want to try it but if you seat the bullet to the lands (start with lot lower charge) or use a strong crimp the start pressure may smooth out and give more uniform velocity. Don't pay any attention to the variations you get between can on and can off and only look at one or the other. The barrel vibrations change between on and off and will drive you crazy if you try to work with both at the same time. Your testing sounds like fun to me but unfortunately I am late in the game and just starting with the 300 fireball and I hope to build a pull bolt pistol chambered in it otherwise I would jump right in :). The only other thing I can remember someone using (with suppressor) in a high volume case is gun cotton as a filler. Not even sure the public can use that now (nitro cellulose but in fluffy form).
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Crimp is with Lee Factory crimp - it's not moving very easy. As Trailboss seems to be the new golden haired child - I might try some with forgotten cousins (RedDot or Unique)... I'm thinking about what I've experienced so far.
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Yep that is what testing is all about. N320 is another good powder for subsonic use. I use that for 9mm subsonics and it gives a very quiet sound signature. Too fast for gas systems but great with blowback and bolt actions. Have to move to N330 if loading 158gr in 9mm or pressure is too high.
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VV320 is great for sub 9, thats what I use in my Uzi and its the quietest. I got that load from Doc Dater. As far as .308 goes I love the Blaylock .30 BGW brass, but I wore my 20 brass out and can't find more. I've always wanted to fill up some of my .308 BR brass with a high temp epoxy to the neck and bore a .300 hole down to the small primer pocket to duplicate the $5 Blaylock brass. I got very consistent groups and velocities with AA#9 as long as the bullets were no heavier than 150 since I have a 1:12. I have the BR brass, I just keep screwing around on the internet too much.
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Subsonic 308 experiment 3 still with trailboss
I've wanted to load some subsonic ammo for my .308's, todays experiments concentrated on my Imbel FAL with it's 21 inch barrel. We had some more rounds to try out. These loads are not recommended and is only for information purposes. This is our day...
All ammo loaded in Remington 308 case's with flash hole expanded to 1/8th inch and 163 grain Pulled Military FMJ Flat Base spirepoint bullets that had been coated with Moly Disulfite dry lube from Bruno's fired by CCI 250 magnum primers. (same as first experiment :wink: ) Weather 76 deg F - sunny, not much breeze... AAC Cyclone can wasn't used today Last time we had taken Suputin's advise and cleaned and lubed between groups of powder trials [http://members.shaw.ca/cronhelm/DevelopSubsonic.html], today we wanted to see if we could use the barrel without special preperation (which is how it would mostly likely be in the field). first loading was 13 grains of Trailboss Can Off - 936.3 1220 Can Off tilt up before firing - 1238 1112 Can On tilt up before firing - 1155 last time in experiment 2 with 13 grains of Trailboss with smaller normal flashhole it gave Can off - Grenade gas setting 1251, 1332 Can ON - Grenade gas setting 1309, 1367, 1340 Can ON - Semi-Auto Setting 1243, 1336, 1317 12.8 grains of Trailboss All Fed from the Magazine Can off - Grenade gas setting 1181, 1202 Can ON - Grenade gas setting 1097, 1313, 1334, 1313, 1338, 1333 12.6 grains of Trailboss All fed from the Magazine Can off - Grenade gas setting 1163, 1199, 1089 Can ON - Grenade gas setting 1142, 1277, 1293, 1158, 1317 Today we got 12.5 grains of Trailboss Can Off - 816.2 1142 Can Off tilt up before firing - 1087, 988.8, 1074 12 grains of Trailboss Can Off - 1080 1070 Can Off tilt up before firing - 904.6, 815.1 11.5 grains of Trailboss Can Off - 795.5, 940.2 Can Off tilt up before firing - 1145, 1092, 698.4 11 grains of Trailboss Can Off - 597 768.9 Can Off tilt up before firing - 680.9 953.1 10.5 grains of Trailboss Can Off - 256.2 , 690.5, 829.0 699.8 Can Off tilt up before firing - 494.3 We terminated the experiment at that point due to low velocities exhibited we had gone below the target range of speed we were looking for. *The TILT UP method involves putting a cartridge in the chamber and then tapping the gun to settle the charge to the rear of the case then gently lowering the muzzle to the rifle rest and firing the charge. The other method of loading the charged cartridges, was done by laying the cartridge on top of the magazine leaving the rifle facing the target and hitting the bolt release, which will distribute the powder more or less evenly over the bottom of the case as the BOLT Rammed it home. NOT all holes in the paper target exhibited roundness with tipping evident, the shorter 150 grain bullets used last time in standard FAL barrel do better. Now keep in mind these where all individually weighed powder charges so they are as listed to with accuracy of the balance beam scale and electronic scales. Conclusions: While lubing bullet with Moly will help with subsonic loads (ie no sticking bullets) I didn't see large difference in it velocity wise. Not even the hottest load attempted to cycle the action. Evidently Trailboss is sensative to powder position (in fact moving the powder to the rear of the case seems to lower the velocity by several hundred feet per second with the same powder charge and I think I may have moved the powder to the front of the case inadvertantly before firing the 256 fps shot :shock: ) we were hoping that opening the primer flashhole up would eliminate this problem but it didn't. While case loading density is less than 1/2 the case, I'm not yet sold that Trailboss is the best choice for subsonic loading. Still looking for better solution for reloading subsonics at home. |
Subsonic reload experiment # 4
Date-April-26-2007 Rifle-Mossburg 800A bolt action Barrel Length-22 inches Twist-1:12 Temperature-94 (warming up) Case-Remington mostly Case Prep-Epoxy Filled to bottom of neck. Flash hole drilled to 1/8”, ˝” up from bottom of case. 17/64” drilled from Case mouth to meet flash hole, Leaving reduced capacity casing. Which was filled with -8.2 grns of Blue Dot Gun Powder. Bullet-150gr SP Remington Moly coated loader to the canalure Lee factory crimp applied. Primer-CCI 250 LR Mag 10 Rounds created and Fired for test. 1st 5 with gun on bench rest cartridge inserted into chamber 1334,* 1321, *1241, *1270, *1214 2nd 5 with cartrdige chambered rifle tipped up and tapped 1079, 1156, 1191, 1723, 1092 Comments, Didn’t use same maker in all cases. (we thought we had) Epoxy fill may not have been consistent as it was loaded to same area but wasn't weighted or measured but the epoxy stated in same state after first firing. Can only be neck sized at this point. Powder load was exact in all loads so unsure of why the 1723 fps round? All rounds fired showed no keyhole effect pretty good grouping. try varying the powder charge on next go round. 308 subsonic experiment #5 Went up into the cool Arizona mountains on 5-09-07 10:00 am 80 deg F at 3170 ft elevation. Used 150 grain PSP Rem loaded over 8.0 gr Blue Dot in epoxy filled and drilled cases 2nd firing CCI 250 Mag primer with primer flashhole drilled out to 1/8" loaded to OAL 2.466 out of 21" FAL 1:12 twist barrel. just loaded from magazine clean oiled barrel. ___case weight 203.0 empty 211.1 primed/powdered gave 1032 fps ___case weight 202.0 empty 210.0 primed/powdered gave 1188 fps ___case weight 207.0 empty 215.0 primed/powdered gave 1198 fps put AAC Cyclone suppressor on ___case weight 203.8 empty 211.8 primed/powdered gave 1195 fps ___case weight 203.4 empty 211.5 primed/powdered gave 1222 fps ___case weight 203.3 empty 211.3 primed/powdered gave 1215 fps just loaded from magazine ___case weight 203.1 empty 211.2 primed/powdered gave 1170 fps ___case weight 205.9 empty 213.9 primed/powdered gave 1113 fps ___case weight 218.9 empty 226.9 primed/powdered gave 1182 fps ___case weight 201.2 empty 218.2 primed/powdered gave 1253 fps Load Density about 65% of the restricted case...skipped tilt test accuracy good - all holes nice and round. |
Today's 308 subsonic experiment
Test date 7/21/07 time 8:00 am to 10:30 am
Temp 98-103 Humidity 36% Sunny and clear Wind 4 knots Far East Valley out of Phoenix AZ Cases filled to bottom of neck with Plastic clay and baked at 300 degrees for 20 min to solidify. Flash hole diameter drilled at 1/8”, 3/16” up from rim. Powder cavity diameter drilled at 3/16”, drilled down from neck to need extended flash hole. Remington 150gr Bullet PSP - moly coated Each case loaded with 3 gr of Red Dot (this loaded filled the cavity 7/8” up from bottom of case. filling the case to the bottom of the neck holds 5.7gr of Red Dot with bullet seated you have room for 4.7 grains of Red Dot) Case—Remington with primer hole drilled out. Each of 7 rounds weighed in grains loaded, velocity in FPS, FAL with or without can, overall length #-Weight..Feet Per second...Suppressed....OAL 1-372.4....486.6...................yes.............. ..2.705 2-374.0...605.1....................no............... ..2.700 3-372.6...525.8...................yes............... .2.700 4-370.8...438.6...................no................ ..2.700 5-374.1...573.2...................no................ ..2.702 6-371.6...372.1..................no................. ..2.699 7-374.0...511.3..................no................. ..2.695 Needless to say I'll be upping the charge to see if it improves the consistancy of velocity and trying to get closer to 1000 fps. |
Hi everybody,
I have done some trials at the range with my 308. It is a Sako action with a 23 inches Lothar walther barrel and a MAE (pes) Suppressor. As We do not have to many types of powders here in NZ, I have used Adi AP50N, behind a 150 grains Sierra spitzer flatbase soft point, federal cases fully prepared, Winchester large rifle primers. With 7 grains the velocities averaged 800fps, with 8 grains I was arround 1000fps and with 8.5 arround 1100 fps. Remember that this load work only im my rifle and that i am not responsible for any accident that may result from you using that load in you rifle... etc. If you have a look at the following link, you will notice that the powder i used is very closed from the Trail boss mentionned earlier on: http://www.adi-limited.com/handloade...ning_rates.asp Next tests will involve the accuracy at 100m . ND |
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