Case Sizing For An AR

K

Kimberguy2004

Guest
I've loaded for bolt guns but this is the first AR that I've ever loaded for. When I put a sized case in the chamber and close the bolt, I can feel it camming into place. It doesn't feel like it's extremely tight and I really can't feel the difference between camming it with or without a case in the chamber, but when I extract the case, the case neck and shoulder have some pretty healthy scratches. Is this normal for an AR, or do I need to start bumping the shoulder until the scratches go away?

Thanks
 
Last edited by a moderator:
I have an AR with a Shilen 1-9 and tubular freefloat handguard with muzzle brake and "match" chamber, work done at Shilen. I have tried various stages of resizing with this rifle and have found little to any measurable difference in accuracy between "minimally resized" brass and others that are run straight through a SB resizer with base of die touching the shellholder! The big difference is... with reliability! I shoot the 69 gr SMK and the 75 Gr Hornady BTHP, the Sierra is a much more accurate bullet in this rifle.
Mark
 
Last edited by a moderator:
AR brass

Kimberguy2004: You did not mention the type of sizing die you are using: a "conventional" or a Full Length neck bushing? For years I competed in NRA HiPower & CMP matches, with several of my AR's, all with "civilian" chambers & never had a problem. Then got the bright idea of using the neck bushing dies that I've always used for my bolt guns. Big mistake. Cases had been properly sized with the shoulders set-back .003" ( I don't set them back for the bolt guns), and in the first rapid-fire string I had to call an alibi since the bolt would not fully close. Another of the same type alibi before the match ended. Returned to the "conventional" die, and now after approx. 3500 additional rds. fired have once again not had any alibis. Two of my 3 chambers were cut by Frank White, Compass Lake Engineering, and all 3 uppers are trouble-free. You may have a really tight chamber, or are not "bumping" the shoulder back far enough/ I like .003"/ works for me. Just some thoughts with the limited information available.
 
I have a bunch of AR uppers all chambered for the 5.56 different chamber reamers and different top barrel makers and different brass and only use one die. Vary early on I got one of Mike Dillon's carbide dies and haven't used any of my others since. Maybe a few hundred thousand rounds later and never a stoppage. I guess I just got lucky? Bullet selection is a whole nother ball game. I really like the Berger's and can get by with the SMK's. You do need to be vary careful with your bullet testing and the range you intend to use them at. Powder selection is a big choice in the .223, you need a lot of attention in this area.
 
In general. I've gone with F/L sizing with semi-auto and lever guns.
I tried a Lee collet neck die and had feed issues in my DPMS .223 Rem chamber.

I've since gone with a Redding f/l bushing die and no issues.

Benchrest Primer had article of Wylde chambered 1:9 twist 26in AR prepped by Bill Wylde. They neck'ed some loads and didn't report issues.

Aside: they shot 69gr SMK with small groups using a variety of powders. Powders were IMR, Alliant, and Hodgdon. No AA, Ramshot, Varget, R15, Norma or VV.
 
I did fail to leave out some important info. First, I am using Redding "S" Bushing type dies with a RCBS Rock Chucker press. This AR is chambered in 20 Practical with a 24" Kreiger SS heavy barrel.
I went through a lot of military surplus brass,LC & FC, that runs fine through my bolt gun, but I could not get them sized so that they would chamber in this barrel without what I thought was too much force. Lapua would size correctly, as would Winchester.
I ordered a couple of bags of Winchester brass, sat down at the press and started working. The Win brass slips into the chamber with almost the same force as no case at all. I'm happy. My die is adjusted 1/4 turn down from touching the shell holder and it seems to work fine. It may yield the sam results set to just touch the shell plate, but I didn't try that. I found somethingthat works, and I stuck with it..
 
Buy a copy of the latest Sierra Reloading Manual and read the chapter on loading for semi auto / service rifles. Then, do what they say. It works. Also, try using a little Dillon case guage when loading for a semi auto like an AR. Great tool. Saves a lot or grief.
 
Mark IV said:
Buy a copy of the latest Sierra Reloading Manual and read the chapter on loading for semi auto / service rifles. Then, do what they say. It works.
Click to expand...
One of Sierra's articles on reloading for semiautos is available online at http://www.exteriorballistics.com/reloadbasics/gasgunreload.cfm . Don't worry about copyright issues, as the site is owned and operated by Sierra Bullets. While some of the information is a little dated (i.e., powered trimmers), it's all still good. One piece of information that has not expired:

NEVER NECK SIZE BRASS FOR A SEMIAUTO RIFLE - EVER.
 
Last edited:
How about the RCBS "X" die?

Have any of you fellows ever used one of RCBC's "X" dies?
They are supposed to limit case length growth.
I just got one in .223,hoping to eliminate the need to trim cases for my AR.
Thanks,
Ron
 
What I do with brass is buy it by selection of lot type and that it is once fired. Then go through my loading and when it hits the ground it belongs to anyone that picks it up, I do not want any of it back. I would like to mention that I use a Wilson case gage to use to set my die to, no worry about case length or setting the shoulder right with this gage. :D
 
relodr36 said:
Have any of you fellows ever used one of RCBC's "X" dies?
They are supposed to limit case length growth.
I just got one in .223,hoping to eliminate the need to trim cases for my AR.
Thanks,
Ron
Click to expand...

I use the RCBS X-die for a M98 in 8x57 Mauser. Works great, very little manipulation of the brass. The directions say trim to a short length, then growth will be slowed dramatically, but it will size more that the collet die. Makes for very consistent ammo.

I am interested in how well it works in a semi-auto. Some on other boards are using it for AR. I like the idea of minimal manipulation of the brass.
 
You must log in or register to reply here.
Back
Top