Stuck cases in AR-15

[392heminut]

I've been shooting my DPMS carbine for years with IMR4895 loads and never had a problem. When my son bought an AR-15 it had issues with the loads I was using. I worked up a load using 25 grs. of H335 under a 55 gr. FMJBT which works great in my son's rifle, but now I'm having issues with my carbine with the load. Every now and then the rifle cycles, but leaves the empty case in the chamber and upon removing the case I find that the rim has been pulled offby the extractor. I still had some of the old loads with the 4895 powder and they shot just fine. I polished the chamber with a .410 ga. bore mop and some metal polish and a drill, which seemed to help a little. Instead of malfunctioning during the first mag full it went almost 2 mag fulls before doing the same thing. I seem to remember the first M_16's having a similar problem back in the 60's and the military found it was powder related. Anyone else experienced this problem with H335?

[MikedaddyH]

I believe you are talking about the stick vs ball powder problem in the early sixties with the developement of the m16 rifle. All of the testing was done with stick powder which burned completly, then when the rifle was deployed in Vietnam the cheaper ball powder was replaced by our military. The lack of cleaning and the unburned ball powder residue in the barrel and chamber caused jamming in the jungle. It was later determined that the moisture in the ball powder was the main cause of this problem.

I have used 7lbs of H335 in 223/556 and 6.8spc rounds and have had zero problems with this powder.

But with H322 I did make a bad batch of 6.8spc rounds which had lube on the inside of the shell after sizing and caused unburned granules to collect in the barrel . This caused a double fire condition which broke a carrier and the extractor.

If you are interested in some H335 loads I can get those to you.

Mike H.

[392heminut]

Mike, I would appreciate any load info you have for H335, I've got an 8# jug of the stuff! :(

[Dusty44]

" I'm having issues with my carbine with the load. Every now and then the rifle cycles, but leaves the empty case in the chamber and upon removing the case I find that the rim has been pulled offby the extractor."

Pressures are too high when the bolt unlocks and starts to move.  Related to the pressure curve inside the barrel/chamber,  length of gas tube and gas port location.

The cartridge case is still being held tight against the chamber walls when the BCG starts to move.  Needs more time for pressures to drop and brass to contract.

Your sticking cases may have a bit more powder from the loading system than the others.  It may be a very narrow difference.  Use of a small-base full-length sizing die might help,  too,  if you are not already using one.  And then there is the possibility that a different primer might fix this for you.  Good luck!

[98Z5V]

I seem to remember this very exact same topic come up about six months ago.  The exact same one, to the letter. 

Am I imagining things?...  <dontknow>

[98Z5V]

Thought I was going a little  :cookoo:

Is it the same situation as this?

http://308ar.com/forum/black-rifles/ar-15-shortstroking-with-reloads/msg26223/#msg26223

[392heminut]

No, that was my son's rifle. His problems disappeared when I switched over to the H335 powder. Now I'm having THIS issue in my rifle with the H335 load that works great in his gun! I think I'm gonna quit shooting and just go bang my head against a wall! Same results, less expense! <lmao>

[98Z5V]

You guys both running 5.56 NATO chambers?  Or is one of these chambers .223 Remington?  I'd gauge both of them just to find out, even if they're stamped one way or the other.  Believe the markings, but verify...

I'm bettin' the chambers are different in those two.  That would go a long way in explaining this stuff. 

[Robocop1051]

I know it's OK to shoot Rem in a NATO chamber, but not to shoot NATO in a Rem chamber... But I don't understand the danger? Will it damage the gun or just fail to function properly (like shown above)? or is there a chance of KABOOM?

I understand NATO is chambered for higher pressure... But I don't exactly understand what physical difference that is from the Remington chamber.

My 14.5" is chambered in .233 Wyld... I eat NATO and Remington with zero issues, all day long.

[unforgiven]

I thought I read there was a slight dimention difference between the .223/5.56 like the .308/7.62. <dontknow>

[98Z5V]

I thought I read there was a slight dimention difference between the .223/5.56 like the .308/7.62. <dontknow>

More than that...  Here's an article by Glen Zediker on it:

Chambers: that all-important point where everything starts

So I don't leave anything out, I'm going to start this off pretending nobody knows nothin'. A rifle chamber is a hole cut in the breech end of a barrel so a round of ammunition will fit. It's a lathe operation. A "chamber reamer" is the tool that cuts this hole and it is shaped the same as a cartridge case with at least part of a bullet stuck in it. The reamer is going to cut out the case body and shoulder silhouette, the case neck, and then extend into the bore to form a bullet profile silhouette. It's here, the bullet profile area, where major tooling differences exist. There are a lot of different .223 Remington reainers. The two most commonly used in factory-done guns are at opposite ends of this universe––one is the shortest, and one is the longest.

Let's look closer. What I called the "bullet profile area" is technically called a "leade." We can also call it the "throat." Inside the chamber, the distance between the end of the case neck and the first point cut into the rifled portion of the barrel coinciding with the barrel's land (rifling) diameter is the preeminent variable determined by the reamer. Land diameter will be the smallest dimension inside a bore. If the first point of full land diameter (usually 0.219" in a 224-caliber barrel) is farther from the end of the case neck (farther into the bore), then the chamber has a longer leade or throat. The bullet won't contact the lands until, of course, it reaches the point on the bullet that coincides with land diameter. I call this the first point of "major diameter" on a bullet. The effect or influence of this conical space ahead of the case neck is simple: The more space the less pressure, and the more space, the farther the bullet must "jump" until the bullet contacts the lands. Read all that again.

Mole Hill And Mountain

Now, SAAMI (Small Arms and Ammunition Manufacturer's Institute) long ago set its standards for .223 Remington based on bolt-action rifles chambered for this round. These bolt rifles were configured for varminting. There was, of course, originally a military chamber and round in use since the .223 Remington commercial round was renamed from the 5.56x45mm (NATO-spec) cartridge. The SAAMI chamber has a good deal shorter leade or throat than a military NATO-spec chamber. There is material elsewhere addressing the reasons this was a bad idea (SAAMI's bad idea), and it's become an even worse idea because it's never really been adequately explained to the folks––like you and me––who load or purchase ammunition for AR-15s. See, off-the-shelf AR-15s can have either chamber. Even worse, some barrels are not marked and some are improperly marked. Compounding matters (but not necessarily making them worse) is competitive use of AR-15s resulted in even more chambering options, and reamers. These came about when 80-grain bullets became available and immediately popular. The SAAMI chamber was too short and the NATO was too long.

So the rest of this will make sense, the following dimensions are all based on an overall cartridge length that will have a Sierra 80-grain MatchKing bullet just touching the lands when the round is chambered. We don't all shoot Sierra 80-grain MatchKings, and we don't all set them to touch the lands, but most competitive High Power Rifle shooters do both. At the least it's a "standard" that gives us a point to work from. What I call the "Derrick Chamber" (Derrick Martin of Accuracy Speaks) needs an overall cartridge length of 2.442"; the "Wylde Chamber" (for competition-use AR-15 pioneer Bill Wylde) is 2.445"; the "AMU Chamber" (for U.S. Army competition team) is 2.500". There are others, but these are the most popular among competition rifle builders. A SAAMI chamber is normally about 2.410"; a NATO chamber is normally about 2.550". Those are huge differences, and I counted five different reamers just mentioned here.

So the rest of this will make sense, the following dimensions are all based on an overall cartridge length that will have a Sierra 80-grain MatchKing bullet just touching the lands when the round is chambered. We don't all shoot Sierra 80-grain MatchKings, and we don't all set them to touch the lands, but most competitive High Power Rifle shooters do both. At the least it's a "standard" that gives us a point to work from. What I call the "Derrick Chamber" (Derrick Martin of Accuracy Speaks) needs an overall cartridge length of 2.442"; the "Wylde Chamber" (for competition-use AR-15 pioneer Bill Wylde) is 2.445"; the "AMU Chamber" (for U.S. Army competition team) is 2.500". There are others, but these are the most popular among competition rifle builders. A SAAMI chamber is normally about 2.410"; a NATO chamber is normally about 2.550". Those are huge differences, and I counted five different reamers just mentioned here.

Bad? Worse? Better?

Which generally bad thing is worse, or better? Chambering specification doesn't matter all that much to accuracy, but it can to round performance––not the same thing. The .223 Remington has a short case neck, a small body and, well, it's not the perfect round for 600-yard performance. It is, however, what we have to work with. Making it work its best means giving as much room as reasonably possible to the long bullets. This is done to prevent seating them so far back into the case. We need all the powder capacity we can get. I'm a fan of longer rather than shorter leade specs. Others disagree. There's no answer that can't be argued beyond an average man's concept of a "day."

The good news is a longer throat doesn't seem to matter to the performance of shorter bullets. That's not to say it couldn't matter, but for it to positively influence groups using, say, a 77-grain Sierra MatchKing, the throat would have to be way shorter than what anyone uses in a High Power chamber. I've jumped to my own conclusion that once bullet-jump exceeds a few thousandths I'm not sure it matters. Jumping .015" isn't going to help much more than jumping .035". Reality is that we're shooting targets for score, and, therefore, we must judge the supposed good or bad effects from compromises by score. It's really common and easy to clean a 300-yard High Power Rifle target, with a high X-count, in a "long" chamber shooting "short" bullets, like the Sierra 77. That target has a 7" 10-ring.

5.56MM NATO VS. SAAMI .223 REMINGTON

Pay attention to this! Out of the box, chances are an AR-15 will have either a SAAMI or a NATO chamber. There are huge differences. Specifically, 5.56x45mm NATO specs call for a longer leade than SAAMI defined for commercial .223 Remington (which was originally determined for bolt-action rifles). Leade is the portion of the barrel ahead of the chamber where the rifling has been conically removed to allow room for the seated bullet. A shorter leade raises pressures. Compounding this, military ammunition is nearly always loaded to higher pressures than commercial. Shooting 5.56mm mil-spec ammo in a SAAMI "minimum" .223 Remington chamber can jump up chamber pressure 15,000 psi, or more. Not all AR-15 barrels are correctly marked, and some aren't marked at all. Know by asking the manufacturer, or just shoot ".223 Remington" ammunition and don't worry. Know also before selecting loading data. If loads were worked up in a NATO chamber (Colt HBAR, for instance), they will be overpressure if used in a SAAMI chamber.

NOT TOO TIGHT

Don't get too "precise" in chambering an AR-15. Leave that to the single-shot crowd who tediously and continuously prepare their ammunition. Don't ask for a headspace that's too tight (short), a neck diameter that's too small, a body area that's too close to new case dimensions, or a leade that's too short. The limits, to me, are found in looking at the ammunition you want to be able to fire in the rifle, and also what you want to obligate yourself to in the way of making dimensional corrections in your handloading process. I believe that an AR-15 chamber should be able to accommodate just about any ammunition. The good news is that you won't see any difference in on-target performance. This rifle can't show it. The main effect of "matching" ammo specs and chamber specs is longer case life and less dimensional change firing to firing. Have the chamber polished and keep it clean!

Between .223 Rem and 5.56 NATO and .223 Wylde, there's even more.  I'll try to post up what I know, and what I can find. 

[98Z5V]

Here's the mechanical differences between .223 Rem and 5.56 NATO chambers:

[98Z5V]

Mechanical differences between .223 Rem, 5.56 NATO, and .223 Wylde chambers:

[98Z5V]

There's also a case-capacity difference between .223 Rem brass and 5.56 NATO brass.  The NATO brass and  .223 Rem brass share outer dimensions to a tee, but the NATO brass has thickness differences in the walls and base - that results in a smaller case capacity over .223 Rem brass.  You load a (smaller case capacity) 5.56 NATO case with published .223 Rem max case load capacities, and you're asking for trouble.  Doesn't matter what your chamber dimensions are.  Chamber pressures are already gonna be higher from the reloading error between case capacities, then toss that 5.56-brassed  hot load into a .223 Rem-chambered rifle, and all hell can break loose. 

[planeflyer21]

Can I pick my nose now?

Jon

[edgecrusher]

you should hear him explain how to cook an omelet  ::)

[unforgiven]

Well done brother <thumbsup> You should hear him explain sex. :o <lmao> <laughs> bring a lunch. <munch>

[MikedaddyH]

Great Info !! Read most of this before.

Tight chambers and NATO cases can cause major problems with a hot load.

Cases capacities are important !

[survivalshop]

First , have you tried factory ammo & how did it work ?

It sounds like you are using just reloads in both rifles , could be a sizing problem , case length ,powder charge too high , or any of the normal problems related to reloading .

Could also be a timing problem with the action ( weak buffer spring , needing one of the heavy buffer types , component failure, etc. too many things to list  )

If you have no problems with factory ammo , I would look into your reloading procedures .

[392heminut]

Well, I believe I have fixed my problem. I got one of those replacement extractor springs with the little rubber o-ring and installed it. Went to the range and no more extraction problems! It's my understanding that extractor springs have a life expectancy, and I have no idea how many rounds mine had been subjected to. The gun was used when I acquired it.