Small Base Dies

RowdyRawhide

RowdyRawhide

New member
For you guys that are reloading for AR's, do you feel the small base dies do a better job of bumping the shoulder back as well. I have standard 223 dies right now, and it seems about 10% are not letting the bolt close all the way, and hitting the FA handle is a waste of time because all it does is make the wedged round wedged tighter. BUT here is the kicker most of the rounds that jam, I can put right back in the mag and they cycle through just fine.

I am wondering if I should get some small base dies and see if that is the problem. Any suggestions would be greatly appreciated.

PS I do not think it is a mag problem because they are all Bushmaster and Brownells magazines. I have some Pmags on the way but not here yet. I also am not filling them to capacity, it does it with only 8-10 rounds in a 20 round mag, so I do not think the mags are the problem.
 
They're all I use, but I have the tightest match chamber commercially offered. For any standard .223 or 5.56 chambered rifle, they aren't needed and they push the shoulder back the same as any other FL die, if they're adjusted the same.

What barrel are you using? I'd suspect you're not getting the shoulder set back quite enough.
The thread is 7/8-14, so each 10 degrees of rotation will set the shoulder back .002 more. Try 10 degrees and I'd bet they'll all chamber fine.
I saw the same thing on my buddies first set of reloads in both of our ARs and that cured it.
If you blacken a "problem" case with a Sharpee, chamber and extract it, you'll be able to see where the interference is.
 
I would also try resizing the problem case just as you have before and try chambering it as an empty case, just to verify its not the loaded ammo.
As a rule, 5.56 chambers are rather (shall we say) forgiving. Some do have match chambers and some are just tight (I have had both) .
 
My AR that gives me fits is a Bushy Varminter. I am using Hornady Dies, and I have the resizing die set so it is within 2 or 3 sheets of paper to the shell holder, I can barely see day light thru the space between them. This is not the first time I have reloaded for it, I have had this problem for several years. It seems that the brass that gives me the bulk of the problems is Lake City, but not a 100%.
 
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All these guys are right. There are a few things that can complicate the issue though.

You may be resizing correctly but the expander ball could pull up the shoulder, and mess up the headspace if the inside case necks are not lubed well enough.

If your shell holder is not a Hornady, it could be to high to allow enough press stroke. As long as you still have some clearance between the shell holder and the bottom of the die, you can continue screwing the die into the press until the resized cases just fit back into the chamber and extract easily. Don't over do it or your headed for case head separations.

Some presses have so much slack in the linkage or flex in the frame, it is hard to get consistant headspace. This is a long shot and not likely with one of the beefy presses.

Another thing that could give you a problem like you described, is an improperly set crimpimg die that is upsetting the shoulder when your seating and / or crimping, as 405 Win said.

My general advice on AR-15 ammo is: No Small Base Dies, No Crimps, No Loads above or below those listed in AR-15 specific loading tables, No soft primers, and ream your primer pockets to a consistant depth.

The reason that your rounds that jammed once and worked on the second try is this. The slamming of the bolt twice on the round set back the shoulder just far enough to chamber. This further convinces me that the interference is on the shoulder and not related to the base size.

All the above assumes that you don't have a fouled chamber in the shoulder area. Severe carbon buildup can imitate a headspace problem in extreme cases.
 
You are loading different brass fired a different amount of times and you
are expecting your die to size them the same? Brass has spring back and
it varies according to it's thickness and hardness. Buy a lyman case gauge
and drop the cases in it after they come out of your press. It will cull the ones
that won't fit and you can size them a little more.
 
Originally Posted By: bigwheeler You are loading different brass fired a different amount of times and you
are expecting your die to size them the same? Brass has spring back and
it varies according to it's thickness and hardness.

Not to be smart @$$, but why full length size then??? To me it would seem that full length sizing would be just that. I understand there will be some "give" in the brass, but I would also think the force of the bolt going into battery would make the brass "give" back if you will.
 
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Typical springback on a good neck is .002 for the dia. How much do you
think the entire length of the case can spring? I have the gauge and know for
a fact that different brass sizes differently. I only bump my shoulders .001 to
.003 on a full length resize and often have to set the die down some different
brands and brass that has been cycled a different amount of times. It always
cures the odd ball large case problem for the ar's.
 
Hmmm. I have both SB and standard dies for my AR.. I noticed no advantage of either .. I did however have the same problem as the OP.. Rounds not chambering and having to use the FA to get the bolt closed. Turned out I needed to apply more lube to the bolt surfaces for it to return properly.. These days all my AR loads are sized with a standard sizer and no issues..
 
Bigwheeler is correct that brass work hardens w/each firing/resizing. A case that has been fired once will remain soft and spring back less than a case that has been reloaded 3 or more times.

Spring back occurs after the round is run through the sizing die, whether small base or standard.

I have never found it necessary to use SB dies except when reloading a batch of brass that had been fired in machineguns which often have "sloppier" chambers than SA or bolt rifles. Have loaded thousands of rounds for bolt guns, Garands, M1A's (w/tighter match chambers) and quite a few rounds for AR's.

Having said that, here is what RCBS says about their SB dies:


Quote: Q. I see a Small Base Die Set listed for my caliber. Do I need these or should I buy a Full Length Die Set or Neck Die Set? How does each set differ?

A. The Small Base Die set is intended for use for ammunition to be used in auto, semi-auto, and lever action rifles so that the loaded round chambers and extracts easily. The Small Base Sizer Die sizes the case from the shoulder to the head of the case a couple of thousandths smaller than a Full Length Sizer Die. In certain calibers it also sets the shoulder of the case back a thousandth or two more than the Full Length Sizer Die. The Full Length Die Set or Neck Die Set is not normally recommended for ammo to be used in auto, semi-auto, or lever action rifles. The Full Length Die set is recommended for ammunition used in bolt action rifles, particularly for ammunition to be used for hunting. The Neck Die Set can also be used to produce ammunition for use in bolt action rifles. The Neck Sizer Die sizes only the neck of the case so it will hold the bullet firmly. It does not size the body of the case nor does it set the shoulder back. Neck sized cases will usually chamber for three or more firings, depending on the powder charge and chamber dimensions. However, over a period of time, a slight drag will be noticed when the bolt is locked. At this point, cases will need to be full length sized and the shoulder set back so they will chamber and extract easily.


Regards,
hm
 
Quote:RowdyRawhide:I would also think the force of the bolt going into battery would make the brass "give" back if you will.


It will, this is why the rounds chambered the second time you ran them through the magazine; your chamber "bumped" the shoulder back enough to chamber the round.

I have personally never witnessed an out-of-battery slam-fire in an AR which I think is due to the design of the bolt being such that the firing pin cannot protrude from the bolt until it (the bolt) is in battery.

This is not the case with the M1 and M1A/M14 and when loading for these particular rifles, one must be extremely careful to be sure the rounds chamber fully and primers are seated fully to avoid slam fires.

I have witnessed an out-of-battery slam fire with an M1 which did considerable damage to the rifle and slightly injured the shooter. Cause was spring-back of cases that had been reloaded 7-8 times (not annealed) and dies had not been adjusted to compensate for the added springback.

Regards,
hm
 
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