Small base dies

[tmjohnson]

My son recently bought and upper for an M4. It has a shaw 16" barrel. I tried to reload some ammuntion for him using a standard RCBS dies and the cases are to large. Is it common to need small base dies for shaw barrels?

[Colorado Osprey]

The deal is many fired cases from an AR platform will not fit back into the rifle they were fired from because there is still some pressure when the gun unlocks. This can cause the case to expand past the chamber dimensions.
To ensure reliable feeding Full Length Dies are required.
Small base dies overwork brass, but are great for reliable feeding.

RCBS makes 3 standard 2 die sets in 223 Remington
#11101 FL Die Set (Full Length)
#11102 Neck Die Set (Neck Sizing only) Great for bolt action on a single gun use
#11103 Small Base Die Set (re-sizes brass under nominal size)

They also have a set for Ar's
#11107 AR Series Dies (Small Base w/ Taper Crimp)

Of course they have other sets like Competition Sets, X-Dies, Gold Metal Match

If you already have set #11101 you will need either 11103 or 11107.
If you only have 11102, you probably only need to step up to a FL set.

[jerrymrc]

Were you loading ammo that had been shot in that gun or some cases that were bought and then sized? Where is it too large? The shoulder or the main body?

One needs to find where the case is not fitting first. I myself am not a fan of small base dies but some like them. I take it that you do not have a case gauge like a wilson.

Barring that inspect and clean the chamber. If this upper was bought used inspect it very close. Once cleaned unless you have some dykem use a sharpie to coat the case and reinsert. let us know where the case is making contact. I am assuming that you used a FL die. [Flower]

[sako55]

Don't mean to hijack the thread. I too have a question about small base dies and figured it might help us both.

Reloaded some 223 will full length die. I was getting primers flattening even under low starting loads. The bulletes were both 65 seirra game kings and 60 gr vmax. Will using the small base dies help with this? The primers were CCI 400's. The powder was Varget going from the starting load up to slightly above 26 grns. Even did it with 25 gr of TAC.

I picked up some rem 7 1/2's hoping the little bit of extra cup thickness will help.

[tmjohnson]

Once fired brass: PMC weighs 92.5 grains plus or minus.5 grains. Cases trimmed to length 1.770. Shoulder measuement is .354
I resized them with a standard RCBS full length resizing die. Double checked to make sure I wasn't pushing the shoulder back when I resized
I smoked some cases and they show contact mid body.
The upper is a RGun heavy 16" barrel with a RRA lower. He also bought a ER Shaw upper and RRA lower. Both are brand new, both have fired 20 rounds of LC ammo he bought on base.

[eneranch]

1.770" is a little long, I trim to 1.745"-1.750". If you FLS & bump the shoulder a little that should not keep the round from chambering. Have you tried cleaning the chamber really well?

[tmjohnson]

Brass chambers with no problem in the Shaw barrel and a Mini -14
Also brass showed no signs of crimping when chambered

[eneranch]

You said the cases are too large. What exactly does that mean??

[tmjohnson]

I remeasured the brass, they are 1.754
The cases won't chamber, there is contact mid body

[eneranch]

Sounds like a Chamber issue, may need to see a Smith.

[Danimal]

I remeasured the brass, they are 1.754
The cases won't chamber, there is contact mid body


Sounds like a Chamber issue, may need to see a Smith.

I would agree with this. I just had a 300 BLK barrel that had too tight of a chamber and I had to return the barrel for a new one. I bought the barrel new though, was the upper he bought new?

Also do factory rounds chamber alright?

[tmjohnson]

Yes the upper is new
It fires factory ammunition perfect.
He'll put a scope on it and see how accurate it is with factory ammo, and then decide whether to leave it as is or ream the chamber.
never know it might be a tack driver

[eneranch]

Seems to me if it fires Factory Loads without a problem, then something is amiss in your Reloading process.

[tmjohnson]

Maybe, I've reloaded ammuntion for 3 other ar's that my son had and had no problem
I had sorted, weighed and trimmed the PMC brass specifically for working up loads.
I did try other brands of brass; Lake City, Federal and Remington and they all have the same problem. I've got a couple hundred cases that I haven't resized, I plan on taking a hard look at my full length resizing die and see if I am doing something wrong.

[Great-Kazoo]

Yes the upper is new
It fires factory ammunition perfect.
He'll put a scope on it and see how accurate it is with factory ammo, and then decide whether to leave it as is or ream the chamber.
never know it might be a tack driver


You can also polish the chamber, unless it is a new bbl, then see what the mfg says.
1.770 is over on resized brass, as mentioned 1.140-1.750 also will repeat the having a case gauge.

[spleify]

I also trim mine to 1.750, 1.760 is SAAMI max

[eneranch]

I've got a couple hundred cases that I haven't resized, I plan on taking a hard look at my full length resizing die and see if I am doing something wrong.

This could definitely cause a problem. I reload on a single-stage press and I make sure it cams-over when FLSing; if you don't size all the way to the base then in a tight chamber it may not fit.

[USMC88-93]

Cases trimmed to length 1.770.


I think max is 1.76 with a trim length of 1.75 off the top of my head.

Edit: nevermind I was late to the party and it has already been addressed.

[spqrzilla]

Target barrel chambers for .223 Remington are going to be shorter in the bullet leade than a military 5.56mm chamber. Good chance that your reloads were out of spec in either OAL or the case length and the other AR's were just sloppy enough to chamber them.

[tmjohnson]

spqrzilla your dead on. setting up my case trimmer I over trimmed one to 1.741 and it cycles perfect.
Problem solved. gun has a real short chamber

[jerrymrc]

spqrzilla your dead on. setting up my case trimmer I over trimmed one to 1.741 and it cycles perfect.
Problem solved. gun has a real short chamber

Good that you found it. Every now and then I have one that has issues and it may be in an AR or AK in .223. I learned a long time ago after measuring and sorting that for rifle I trim every time.

An extra pain in the ass but since I stopped sorting and just trim every one as SOP the problem has gone away. [Beer]