308 subsonic

[pug]

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.

[Artful]

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 )

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.

[pug]

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).

[Artful]

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.

[pug]

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.

[jarhead1086]

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.

[Artful]

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 )

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.

[Artful]

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”, ½” 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.

[Artful]

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.

[d-mon]

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