Rule out needing small base dies

[smoothy8500]

Just built a second upper with a match barrel. My reloads that I always fire in my CAR-15 often will not fully go into battery on the match upper. No problems at all with factory ammo. I'll list the things I checked and see if I overlooked something.

All reloads are RCBS Full Length sized. Case trim is .010" below max. Cartridge Over All Length is OK. No burrs on case mouth. Crimp is not the issue. Sized/trimmed cases checked with a Wilson case gage.

Barrel headspace checked with GO-NO GO. Factory rounds drop right into the chamber. However, an unloaded sized/trimmed case will not fully go in the chamber. It will stick out about 1/8 of an inch, even with finger pressure.

Unless I overlooked something, I'm guessing my CAR-15 has a generous chamber and the match barrel is on the tight side and will require small base dies.

[GeoffLinder]

Get the Dillon .223 die and don't look back. I gave up on all RCBS dies (including the small base one) for .223/5.56 in AR's a long time ago.

Just set the die for enough shoulder setback to give you about 2 thousandths headspace and you should stop having problems.

My JP AR has a .223 Wyldie chambering which is even tighter than standard .223 (which is a tad tighter than 5.56mm) and everything from a Dillon die set right works like a charm.

I recommend getting the non-carbide version as most of the time you will wind up setting the die so that there is a little bit of cam-over on the shell plate. This will crack a carbide die over the long haul. You are going to be lubing the cases anyway so who needs carbide

[echoarms]

Dillon are small base dies.

[J-cat]

Wylde chambers are larger than 223.

[ireload]

RCBS small base size die is what I use for my AR. You could be right about the tight chamber.

[GeoffLinder]

Wylde chambers are larger than 223.

Doh!, you are correct sir

BUT, they are not really any different in case and chamber dimensions. The difference is in the throat or barrel leade area. .223 starts the rifling a little earlier, .223 Wyldie has some clearance added to allow NATO type bullets to not hit the rifling when chambered and 5.56 is a little bit more loose here to allow for tracer ammo tip clearance.

Basically, it's all about bullet jump distance differences.

[smoothy8500]

Thanks for everyone's input. A friend has a RCBS SB die set that I can borrow. I'll resize some brass and see how well they fit in my chamber and go from there. I casually searched forums on SB dies and it seems that 99 to 1 hate SB dies. Obviously some of you here and my friend have positive experience, so maybe the negative responses are just hype or uneducated guesses.

[GeoffLinder]

It's the RCBS SB die that is hated and reviled, not ALL SB dies are crap. This is why I recommend the Dillon one. Redding dies are also very good, but for general .223 usage the Dillon is the schiznit.

9 out of 10 SB die stuck case stories feature the RCBS SB die.

[smoothy8500]

Well, if I have to buy SB dies, I'll know which ones to get.

[Ahhnother8]

My reloads that I always fire in my CAR-15 often will not fully go into battery on the match upper.

Where did the brass come from? Was it ALL fired in THIS rifle?

[J-cat]

Doh!, you are correct sir

BUT, they are not really any different in case and chamber dimensions. The difference is in the throat or barrel leade area. .223 starts the rifling a little earlier, .223 Wyldie has some clearance added to allow NATO type bullets to not hit the rifling when chambered and 5.56 is a little bit more loose here to allow for tracer ammo tip clearance.

Basically, it's all about bullet jump distance differences.

Not really. I have looked at JGS reamer prints for the 223 SAAMI, the 556 NATO, and the Wylde chamber designs.

Wylde chambers have NATO bodies with a .2245" diameter freebore. NATO freebores are .227", some .003" over bullet diameter. 223 chambers have narrower bodies.

[GeoffLinder]

Freebore is not a "chamber" dimension, it's part of barrel leade/throat area in front of the chamber.

Compare the specs in the following link (standard chambering reamer dimensions) for the PTS .223 reamer vs. the PTS 5.56 reamer. The freebore is all that is different in any meaningful way (1 ten thousandth of an inch is not meaningful).

http://www.ar15barrels.com/data/223-556.pdf

Check dimensions C, D, E, F, K, M, & Q for the PTS reamers (always compare same brand reamers as every Mfgr has a different idea of what is correct). I trust PTG reamers, never been a fan of Clymer, but do also trust the JGS ones. Also note that the JGS 5.56 reamer agrees with both PTS ones in every "chamber" dimension too.

They are all within a couple ten thousandths on the actual chamber dims. The only meaningful variances are in G, H, N & R dimensions which all relate to throat/leade area which is where the differences are here. So as you can see, the difference is all about bullet jump distance and throat bump clearance for bullet tips

[smoothy8500]

Update- A friend of mine let me borrow his RCBS Small Base dies. I sized a few pieces of brass that were fired from my other rifle. I tried them in my new barrel and they all dropped right in. I then resized 400 pieces of brass I had laying around. I didn't notice any more case stretch that using regular Full Length dies. I guess I will have to buy a set of SB dies-Dillon or Redding of course.