Initial loading issues

[jinx44]

I assembled an AR in .300 whisper with parts from a local dealer. I believe the barrel is a J&T. My dies finally came in yesterday and I started to load some rounds last night but encountered problems.

Dies are Redding FL (adjusted down to touch the shellholder), brass is .223 factory remington, case length trimmed to 1.355", bullets are 220MKs.

I started by loading the OAL so they would fit in a standard metal LE mag. Then I tried to chamber one and the bolt wouldn't close. I shortened the OAL, and after several tries, it finally chambered. I fired this round and it was super-sonic at 9.7gr of AA#9. The case didn't eject. It was easily pulled by manually ejecting the case. I am sure I felt the action cycle, and there seems to be a mark on the case head from the ejector trying to pull it out of the chamber.

I then took a sized case and cut 4 slits in the neck and inserted a bullet so I could find where it touched the lands (read about this trick on a 300 whisper page that was linked from this site). This case wouldn't chamber either. The bullet was loose enough in the case that it should have easily pushed back if needed. So then I tried to chamber a freshly sized, empty case and the bolt still wouldn't close. It required considerable force to get the bolt to close. When I extracted this case, there were marks on the shoulder where it seems the chamber was pushing back on the shoulder.

I compared this case, a loaded case, and the fired case. The neck on the fired case is MUCH longer than the neck on a sized case. .265" on the fired, .221 on the sized. The shoulder also appears to be pushed downward, but is extremely hard to measure because the shoulder of a sized case is not very pronounced.

Obviously, either my chamber is too short, or the dies are loading the case too long. It seems my reloading manuals disagree on dimensions. Where can I find the correct SAAMI specs?

Also, sized case neck OD is .333", loaded case is .334", and fired is .336". Is that correct or a little tight?

[amafrank]

There is no saami spec on this case yet and there is more than one set of specs. I chambered my barrels with a Dave Manson 300-221 reamer and most cases will fit fine using the CH4D dies. I tried some dummy rounds loaded by a friend with redding dies and they did not fit. There may be a die problem or a chamber problem depending on who's reamer, dies and cases you are using. One other problem very commonly encountered is the thick neck due to heavier walled brass in military cases. I've found a few different types that must be neck turned just to fit the chamber. For the most part I've decided to use only winchester or Lake city brass from now on. Both have been pretty consistant and require no special treatment. What your problem may be is exactly the thick neck and putting a bullet into the case prevents the neck from "squishing" enough for the bolt to close. I've had some of these heavy walled necks that even after sizing they still won't fit the chamber when there is no bullet in them. I've never tried hammering the bolt home as I don't want to have to hammer it open. If it doesn't fit it doesn't fit.

Good luck
Frank

[pug]

The necks on mine run about .330" loaded on average. I would say if the fired neck is .336" then that isn't the problem but worth trying some different brass anyway. If thats ok then maybe you can pick up another shellholder and have someone take .010" off the face of it. This will give a similar effect of using a small base sizer die as it will allow you to push the shoulder back a little farther and also size the body smaller. I would not think it was the dies. It may be the brass, barrel being short chambered or else your bolt could be out of spec. I had one of those where the cup in the bolt face was too shallow and caused the problem you describe. Depth of cup is .122" on one just measured if it helps. A headspace gauge would rule out the chamber and bolt instantly if you could get your hands on one.

[jinx44]

Well, I found part of my problems. The brass I started with was S&B .223 Remington. The case was obviously too thick. Last night I loaded some winchester brass and my loaded neck diameter was .331 instead of .335. Fired neck diameter was .334 instead of .336. The brass worked easier and the shoulder was pushed back to where it should be to chamber.

It seems I am hitting the lands at 2.112" OAL with the 220 MKs, so I am loading to 2.110. I tried 8.4gr of AA#9 and it has a supersonic crack. How heavy should I crimp the bullets? I am crimping by turning the seating die in 1/8th turn from when it touches the case. I pulled a couple bullets with an inertia puller and there were no marks on the bullet, but they required several solid blows to come out.

Now, my next problem is ejection of the fired cases. It seems the action is not going back far enough to eject the spent case. The case comes out, but not far enough to clear the breech and the action hangs. I am using a standard AR front sight/gas block, 16" barrel. Does it possibly not have enough pressure? As I said, they are still supersonic, so I know the problem will be worse when I load subsonic.

[interceptor]

Cycling: You have a few things you can try.

One, are you using a carbine or rifle length receiver extension tube? If a rifle length they you could try a carbine spring with your rifle buffer.

Two, if a carbine system then you might remove a coil at a time.

Three, reduce the weight in your buffer. (to get my rifle length to cycle properly I pulled the weights and replaced with aluminunm total buffer weight of 88 grams)

Four, pull the gas block and enlarge the port one number size drill at a time and replace with an adjustable block.

Five, you ain't gonna like this one, have a smith turn your carbine barrel port into a pistol length port. (more dwell time)

Six, try a different load. For instance, I'm using 11.8g AA1680 with 220g SMK.


These are a few options off the top of my head, none are guaranteed and use at your own risk. I did get my 16" carbine barrel (+ can) to cycle with subs by using a carbine spring and a reduced weight buffer. These are easy mods, and non permanent too. If you want to pursue the lightweight buffer thing, then a trip to your local hardware store for some 0.5" solid alum rod will get you started. IIRC, cut length was 4.625" for me.

[jinx44]

Interceptor, thanks for the info. All of the ARs I have had in the past were .223, so I have never had to deal with cycling issues.

I am using the rifle length extension tube. I believe I have a carbine length spring at the house as well. That will definetly be the cheapest way to try, so I will start with that.

[pomofo]

That 2.110" load you posted shows up in Quickload at 42339 psi, with MV of 1258 fps. I think some people suggest using a slower powder such as 1680, depending on where your gas port is located. Is it at the pistol or carbine position?

[jinx44]

That 2.110" load you posted shows up in Quickload at 42339 psi, with MV of 1258 fps. I think some people suggest using a slower powder such as 1680, depending on where your gas port is located. Is it at the pistol or carbine position?

Gas port is Carbine length.

I would think 42,000psi would be plenty to cycle the action?

What length is everyone else loading the 220 SMKs to?

[JFettig]

42000psi is at the chamber, when the bullet gets to the port its significantly lower, especially with faster burning powder.

Jon

[jinx44]

Update:

I am still using AA #9 due to no local shop having 1680 in stock. I started cutting the buffer about a coil at a time, then a 3 coils shorter than factory, the rounds started having problems chambering. I went back to a stock length spring and pulled weights out of the buffer. Even with all 3 weights pulled, it wouldn't eject the shell. The action moves backward when fired, just not enough for the case to clear.

I reduced loads .2 gr at a time to try to get rid of the crack. Even at 6.0 gr AA9, there was still a crack. Unfortunetly, I don't have a chrono, but that is about to change. Anyway, at 5.8 gr, the bullet stuck in the barrel about 3" from the end, and the case actually ejected and loaded another round. I knocked that bullet out, cleaned the barrel, and loaded up another at 5.8 to make sure there wasn't an issue with the primer or something on the last. It also stuck about halfway between the gas port and muzzle, and the case ejected and loaded just as it should.

So when I stick a bullet in the barrel, it will cycle.

[interceptor]

So when I stick a bullet in the barrel, it will cycle.

So hows you accuracy at that point?:grin:


IMO, you're going in the wrong direction with your loads, down instead of up. You describe hearing a crack when shooting... Next time out let a partner do the shooting and you stand 50-60 feet away, see what you hear. I think you'll be suprised at how quiet it is.

My load is 11.8g AA1680 under 220 SMK's, and from 100 ft away (with YHM can) it's like an air gun. AND IT CYCLES THE BOLT, FULLY, CHAMBERING ANOTHER ROUND. I do run a carbine spring in a rifle length tube with a 88gram buffer.

[pomofo]

At 6.0 grains, Quickload is showing 981fps, kind of curious that you're still getting a crack. The 11.8 grain load with 1680 that was mentioned earlier is supposed to be getting 1251fps (16" barrel), loaded to mag length. The problem with 300 Whisper is that you're using relatively small amounts of fast powder to push heavy bullets. Chamber pressure may be high, but it diminishes rapidly.

Quickload also provides estimates of muzzle pressure, which indicates how much pressure is lost in travelling through the barrel. That 1680 load is supposed to be ~2700psi at the muzzle, as opposed to 1900 for your 8.4gn of AA9, and 1500 for your 6.0gn. By comparison, 5.45x39 still has about 11000psi at the muzzle. Muzzle pressure curves are parabolic, so they increase and decrease at some exponential rate. My guess is that if you're losing 40000psi over 16", much of that came before you hit the gas port at 7".

[jinx44]

So hows you accuracy at that point?:grin:




Well, I am pretty sure if I would have left that bullet in the barrel, and shot another round, it would be accurate enough to stack bullets on top of one another. LOL

The crack I am hearing is out away from the gun, as in it sounds like its a hundred yards away. The sound of the rifle isn't loud at all.

I am trying to dig up a chrono, so I will see exactly where I am at. I really appreciate the help you all are giving me, and being patient with a newbie.

[Flewis]

For what its worth, I'm using 11.6 grains of AA-1680 behind a 220 SMK and am getting 1080 fps. Cycles the bolt every time and locks back on an empty mag. I have a 16" barrel with the gas port at the carbine position. I never had any luck with H110... never would cycle either of my rifles. Oh, and my gas port is 0.125.

[jinx44]

I had a chance to play with some 1680 yesterday. Cycling problem has been fixed with this powder. I started with 11.0 gr and still heard a crack. 45* air, and I think we are roughly 450' elevation.

Though according to this calculator, elevation is not important: http://www.sengpielaudio.com/calculator-speedsound.htm (http://http://www.sengpielaudio.com/calculator-speedsound.htm)

By putting 45* in there, SOS is 1101 ft/sec. Fired brass on these winchester casings are showing the neck is not too tight. I am still loading at 2.110", which is .002" off the lands. I have thought about seating deeper incase that is causing a pressure rise, but I feel they are short at that length anyway (which may be causing higher pressure).

My next step is to get a chrono to verify if my ears are deceiving me. Now I just have to decide which one. I have been reading good things about the CED Millenium. Opinions?

[Flewis]

Are you sure you aren't hearing the report of the rifle bouncing back to you from a hillside or berm and mistaking that for super-sonic crack? With 11 grains of 1680 I'd be really surprised if you are going super-sonic.

[redtazdog]

Are you sure you aren't hearing the report of the rifle bouncing back to you from a hillside or berm and mistaking that for super-sonic crack? With 11 grains of 1680 I'd be really surprised if you are going super-sonic.
I was thinking the same thing because I use 11.4 grns of 1680 and get
1040 fps through the pact chroni.

[jinx44]

Are you sure you aren't hearing the report of the rifle bouncing back to you from a hillside or berm and mistaking that for super-sonic crack? With 11 grains of 1680 I'd be really surprised if you are going super-sonic.

I have been wondering the same. Tonight I am thinking of going to 12.2 grs, which should definetly be supersonic and compare the sounds.

[Pitt300]

If you're hearing a "reflected crack" from the targeted background, that's supersonic crack.

Normally you will not hear the "boom" of the gun being fired as a "high" reflected sound.

Have someone stand away from you when you shoot & see if they hear a "crack" down range.

[jinx44]

Since progress has been put on hold until I can get my hands on a chronograph, I thought I would make a change that I have been wanting to do. When I picked up the parts for the build, I was able to get a billet Sun Devil lower for the same price as a RRA. I liked the tension screw in the Sun Devil that can tighten against the rear pin to tighten the receivers together. The upper was just a standard J&T flatop with forward assist. I went back last night and picked up a Sun Devil billet slick side upper and swapped them out. Even before adjusting the tension screw, this is BY FAR the tightest AR I have ever built. They make for a very solid gun.

Here are some pictures:

http://i13.photobucket.com/albums/a288/jinx44/IMG_5402.jpg

http://i13.photobucket.com/albums/a288/jinx44/IMG_5401.jpg

http://i13.photobucket.com/albums/a288/jinx44/IMG_5403.jpg

http://i13.photobucket.com/albums/a288/jinx44/IMG_5404.jpg


Internal of the SD lower. Note the tension screw with the green face in the back:

http://i13.photobucket.com/albums/a288/jinx44/IMG_5400.jpg


Look at how beefy the upper is:

http://i13.photobucket.com/albums/a288/jinx44/IMG_5399.jpg


Picture of the tension screw head with the grip removed:

http://i13.photobucket.com/albums/a288/jinx44/IMG_5398.jpg



I ordered another set of Sun Devil receivers, blue anodized, for a 6.5 Grendel build.

[amafrank]

On your question about crimping you are better off not crimping at all. The crimps can vary considerably without you noticing any difference in the handle pressure. There is no real reason to crimp with this round even in a semi auto since the recoil is so low you won't pull any bullets in the mag. I have been using H110 and 2400 with great results both accuracy wise and with brass life too. I am primarily shooting bolt actions but I use the ammo in the SIG 552 as well. I had to do a bit of super modding on the gas system to get reliable cycling and the AR platform is not much different. I can tell you that the difference between different powders is enough that one load will not cycle the gun though its supersonic where another will cycle fine subsonic. Powder selection is a very important consideration in operation.
Glad you are getting some of this stuff worked out and good luck
Frank

[jinx44]

Chronograph came in yesterday. I went with just an entry level, cheap one as my first chrono. Its the Shooting Chrony F-1 Master with the remote display.

Of course, it was dark when I got off work last night, so I couldn't play with my new toy. However, lighting was perfect this morning. Temp was 33*, and I set the chrono about 10' in front of the bench.

I had loaded 2 each of 5 different amounts of 1680 for chrono testing, but I just started with the lowest load which was 11.2gr. Seeing as how its the last day of deer season here in MO, I didn't want to shoot too many times incase any of my neighbors were waiting for that last chance at a big one.

The 11.2 gr loads yielded velocities of 1061 and 1080. I walked back inside and quickly loaded a round at 11.0gr, which had a velocity of 1026. I wasn't sure what the SOS was at that time of day, but after looking it up when I got to work, it should have been around 1088 @ 33*.

All of the rounds still had a "crack". So obviously I am sub-sonic now, and it has just been an echo that I have been hearing. Now its time to sit and wait for the paperwork to obtain a can to go through.