Puzzle: How did my reload lock up my AR?

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Baron

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Hey all - had a very interesting failure today with my AR. The reason I'm posting this here is that I was using reloads.

I'm trying to work up a load that's ballistically identical to XM193 for consistency/SHTF if necessary. I'm using 55 gr. FMJs over H335 with CCI 450 magnum primers. Today I was testing loads by shooting 5 rounds of 23 grains followed by 5 rounds of 23.2 followed by 5 rounds of 23.4 and so on. The rifle is a 16" midlength chrome-lined Rock River.

Dropping the trigger on my third round containing 24.2 grains resulted in what sounded like a dry-fire. I waited ten seconds in case my rifle wished to break the world record for a hangfire, then tried to eject the guilty round. The bolt would not budge. After a few minutes of pulling, I could get about 1/16" of play in the bolt by alternating pulling with mashing the forward assist. Finally I removed the optics and slammed the butt into a log, resulting in the round ejecting immediately.

The primer was untouched save a very small indent in the very center, which I assume might be what happens to most rounds when chambered in an AR. There was also a small circle around this small indent, perhaps half the size of the primer itself. These marks were very slight but very clear.

I field-stripped the rifle and everything looked to be in order. I loaded up the remainer of my ammo and it shot perfectly. I went as far as 24.4 grains and no pressure signs were apparent.

So, as I would like to prevent this catastrophe from occuring, does anybody have any ideas as to what caused this? When it was locked up, I pulled the bolt very hard with no luck - this has me scratching my head. I thought it might just be a stubborn primer, but the primer was clearly never hit by the firing pin perhaps save the light tap from chambering.

Thanks, all.
 
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Just a wild guess...

Sounds to me like the brass never got sized properly, therefore the case got lodged most of the way into the chamber. The rifle wouldn't fire because it wasn't in battery. The dimple on the primer was made when you jostled the rifle around trying to get the action open.

Try to manually slide that same case into your disassembled rifle's chamber and/or measure it and compare the dimensions to the drawings in your RLM for 223.
 
Wow, good call - I'll take calipers to the round first thing tomorrow. That's a very good idea - but how the heck could I have decapped that piece of brass without resizing it? I'm using the RCBS x-die, and like all dies it doesn't decap until the very end of the press stroke. While I can't figure out how a case could be decapped but not resized, this does indeed seem to be a very plausible explanation. Also, would the firing pin dropped in the bolt wasn't fully closed? I could not put the rifle on safe, which means the hammer did drop...

Many thanks! Other theories, anybody?
 
The brass needs trimming. Or as said above you did not full length resize that round correctly. Also, some reloaders have turned the bullet seating die down to far getting into the crimp part of the die and not know it. To much crimp can bulge the neck/shoulder.
 
More excellent ideas. I don't claim to trim all of my brass to precisely the same lengh despite my good efforts, so I'll check case length first. Second, I had a bit of trouble getting my dies to cooperate with crimping, and I probably have the sizing die adjusted to far down. I'm used to Lee Factory Crimp Dies, and when I crimp .45 and .357 SIG the press takes considerably more force.

Although the other 45 rounds fired without incident, this makes good sense; I'll lighten the crimp and reperform the thumb test to be sure it's tight enough; hopefully then I won't have more problems.

Many thanks!
 
If your crimping, all cases have to be exactly the same length. Unless you buy a taper crimp dies. I do not crimp, i dont find a need for it.
 
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Crap...my cases are mostly all the same length, but as I didn't caliper every last one I can't promise they're all the exact same length. They are certainly all within one thousand and probably within 1/2 thousandth - is that enough or should I get a taper crimp die?

I'm aware of the considerable debate for and again crimp - I see it as a bit of extra insurance which I appreciate in a has-to-work load. Especially since if I can crimp in the same stroke as bullet seating, it's too easy not to do.

Thanks.
 
If you must crimp, i would get a taper crimp die. Remember i dont crimp, so you might want to get advice for others. I taper crimp for pistol, not 223. It only takes 1 case that needs trimming to lock up your rifle as you found out. Your call.
 
If you're going to do a lot of reloading it's best if you spend the $20-30 bucks and get yourself a chamber gauge, on my reloads I drop a ready to load piece of brass in my gauge at the begining and around every 50-75 rounds just to make sure nothing has moved on me or if a certain piece of brass acts goofy while I'm sizing to make sure it will work.
 
Like the previous posters my first thoughts are not resized enough and get a case gauge. My guess is the case is right on the edge of being too long. Once in a while I would get cases the had rim defects hard to see but the case gauge would catch it. Rare but it does happen is I get a case that just wont make it into the gauge but I can't find what the problem is. I resize it & it still won't fit. I trash it & move on.
Rim defects were averted with adequate case lube & making sure the shell holder was good. On a Dillon if it is loose it tilts on extraction & that combined with inadequate lube caused me problems. The Serbian brass was mainly the problem.
 
Most all my .223 brass is range pickup. It seems a lot of military and police brass that I pick up at the range is slightly longer (maybe .020") than commercial bought cases. Maybe it's the difference between 5.56 and .223, maybe it's crimped vs un-crimped, whatever it is seems to always have a serrated looking case mouth. I simply set my trimmer, pop any suspicious looking ones into the trimmer, and let it decide.
 
Range Brass & Brass Fired in a Different Gun

If brass was fired in a different gun and that rifles chamber is bigger then yours, the web area of the case can jam your gun. This web area in never expanded on firing unless the pressure/load was TO HOT . Some times the primer pocket will get inlarged. Standard Full length sizing dies do not make contact with the web area in most cases. This web area can jam in you chamber/action. Another problem with range brass of different headstamps is they will grow at different rates. Some will need trimming sooner that others. If you crimp using normal roll crimping when seating the bullet, this becomes a problem. A taper crimp dies should help in this area as the trim length is not criticial. As said above, a Wilson case gage can be useful in sorting out the really bad case, but the gage is not a total fix all IMO. You chamber is still the best gauge. The web areas are marked in this photo. If the web area expands on firing, you load is TO HOT. WebMarkedCase_01.jpg
 
243 so if a 223rd was fired in a 556 chamber somebody picks the brass up reloads it and shoots it in a 223chamber it can cause this problem?that baron had?
 
Perhaps the case was not sized quite enough. A case gauge will show that. Another possibility is that too heavy a roll crimp caused problems and buldged the case. That can happen when one case that is too long slips by "quality control". Sometimes you will have a work hardened case that has more "spring" to it than the rest and will not be sized enough with the sizer set for the average softer brass. As already stated, a taper crimp will be more forgiving, but the cases should be checked for length anyway.

Many chambers are tighter than mil spec to give a little more accuracy, but they are less forgiving with ammo. That is the reason military chambers are "generous" in their dimensions. They have to be reliable above all else.

Unless it is a target rifle, or something you are mainly going to shoot groups with at the range, or a varmint rig, I want a mil spec chrome lined chamber/bore for reliability.

For ammo that has to be reliable, check all your sized brass in a gauge. That will check length, width, headspace, etc and make sure it is ready to load. Then check it again with a case gauge after loading to make sure it is still in spec. It's OK to jam up your varmint rig, but not a battle rifle.
 
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1) Size that range pickup brass in a small base die.
2) Set up your die with a cartridge headspace gage.
3) trim the brass.

I don't have a X-Die small base die, I don't know if it will keep range pickup brass to the correct OAL.
 
if a 223rd was fired in a 556 chamber somebody picks the brass up reloads it and shoots it in a 223chamber it can cause this problem?that baron had?
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In most cases NO. The flrs die will put the case back to spec. The web can be to large IF the load used was to HOT, an over load that expanded the web. Its Rare, but happens. I am guessing that Baron's problem was crimping?? One of the basic rules of reloading is "don't use brass that has been fired in a different gun" But no one follows this except maybe benchrest shooter that want top accuracy.
 
Not necessarily. A full length resizing die does not reduce a case by much. Sometimes a case has expanded so much, due to a ballon chamber, that a small base die won't bring it back down.
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This is why small base dies are needed sometimes. All guns are different.
 
10 to 1 it has nothing to do with resizing, and very little to do with case length.

Except if you didn't trim them exactly all the same.
And crimped them in the seating die.

If so, you collapsed the shoulder from the excess crimp.

That will lock up an AR-15 tighter then a northbound Bull's south end!

If you still have one of the tight rounds, color it with a black magic-marker and chamber it again.

I'll bet you a beer the marker is rubbed off down to shiny brass right behind the shoulder.

If that proved to be the case you can do one of three things.

1.Trim every case exactly the same length.
2.Get a LEE FCD collet crimp die. (Length is non-critical)
3. Don't crimp at all.

rcmodel
 
If so, you collapsed the shoulder from the excess crimp.
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The one time I jammed a "match" chambered AR, that was the problem, despite the fact that the round, once removed, would chamber in my Mini 14 and my other AR. Solution? Got rid of it for a mil spec chambered upper. ;)
 
By any chance is the bullet seated too long? I've had one or two dislodge and hit the rifling causing the round to require a lot of effort to eject.
 
Solution? Got rid of it for a mil spec chambered upper.
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That won't work either.

The time I did it, in 1971, they locked up my slick-side mil-spec 5.56 SP-1 Colt tighter then Al Gores belt!

I ended up firing them in a Mini-14, but only because I could beat on the bolt handle hard enough to make them chamber!
Or stomp on it to get them back out if they didn't chamber.

The really weird thing is, the buckled shoulder is so minuet, you can't see it without blackening the brass with a candle or marker, and running it in the chamber.

rcmodel
 
That won't work either.
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It did for me. My round must not have been all that out of whack. It would fall in and out of my Mini 14 chamber, and chambered easily in the Model One Sales uppers chamber I bought for a blaster. Maybe it is bigger than mil spec. :scrutiny:
 
The really weird thing is, the buckled shoulder is so minuet, you can't see it without blackening the brass with a candle or marker, and running it in the chamber.
Click to expand...

It is so surprising to read of so many crimp issues in AR's, when there is no need to crimp.

I don't know any highpower shooters who crimp match bullets for use in their AR's. There is absolutely no need to mess up a good match bullet for no purpose. So I never see problems related to over crimping on the firing line.

Instead what I see is shooters having jams in their nice match chambers with once fired military brass, or brass used in their Rambo rifle.

And that is related to not enough sizing, or over length cases.
 
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