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#1926738 - 05/30/11 10:47 PM Sizing Die setup for an AR-15
SDCoyoteCaller Offline
Die Hard Member II

Registered: 05/10/01
Posts: 1772
Loc: South Dakota
Guys, I have been reloading for bolt guns for over 17 years now, but I have never reloaded for an AR. I have read the Sierra manual's section on reloading for an AR, and feel comfortable with the specifics you need to be mindful of. I do have one question though. When setting up your full length resizing die, how far back do you bump the shoulder to ensure reliable function in the AR-15? Thanks.
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#1926750 - 05/30/11 10:59 PM Re: Sizing Die setup for an AR-15 [Re: SDCoyoteCaller]
fw707 Offline
Moderator

Registered: 03/18/09
Posts: 5809
Loc: Up a Holler in KY
Set your FL die to bottom out on your shell holder. Your brass should function in any chamber then.
Neck sizing dies are usually set for bumping shoulders back, and that's more often used for brass in a bolt gun.


Edited by fw707 (05/30/11 11:03 PM)
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#1926754 - 05/30/11 11:04 PM Re: Sizing Die setup for an AR-15 [Re: fw707]
markley Offline
Die Hard Member II

Registered: 11/12/10
Posts: 1334
Loc: Iowa
plus one on the bottom of the shell holder. i use the same die for my bolt gun and ar and works great in both.

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#1926760 - 05/30/11 11:08 PM Re: Sizing Die setup for an AR-15 [Re: markley]
mikeyg Offline
Seasoned Member

Registered: 12/30/10
Posts: 306
Loc: S.W. Wisconsin
+2 on the bottom out on shell holder.
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#1926765 - 05/30/11 11:18 PM Re: Sizing Die setup for an AR-15 [Re: mikeyg]
SDCoyoteCaller Offline
Die Hard Member II

Registered: 05/10/01
Posts: 1772
Loc: South Dakota
Hey guys,

Thanks for the answers. I was kind of looking more for a specific number. I use the Hornady headspace gauge to set-up my dies, and in my bolt guns I move the shoulder back .002" or so, usually. Just wondering how much to move it back with my ARs now. I was thinking .005". Maybe I am overthinking all this, also. Thanks.
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#1926771 - 05/30/11 11:25 PM Re: Sizing Die setup for an AR-15 [Re: SDCoyoteCaller]
fw707 Offline
Moderator

Registered: 03/18/09
Posts: 5809
Loc: Up a Holler in KY
Originally Posted By: SDCoyoteCaller
Maybe I am overthinking all this, also. Thanks.


You're not overthinking it. You're applying bolt gun methods to a semi-auto gun.
The body of the case needs to be sized back to function in the AR chamber.
If the case is a little too long in a bolt gun, the bolt won't close and you'll know you've got a problem. If the case is a little too long or the base hasn't been sized back smaller than chamber dimensions in the AR, you have a possibility of the case sticking in the chamber before it seats fully, and you can have the round fire out of battery. Then you'll know you have a BIG problem.
If you're lucky, the round won't fire, but the force of the bolt will have stuck the oversize case so tight in the chamber that you'll have to drive the live round out from the muzzle end.

Full length sizing is the only way to go for an AR. Some folks even go so far as to use small base dies for a little extra squeeze.


Edited by fw707 (05/30/11 11:37 PM)
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#1926777 - 05/30/11 11:29 PM Re: Sizing Die setup for an AR-15 [Re: SDCoyoteCaller]
mikeyg Offline
Seasoned Member

Registered: 12/30/10
Posts: 306
Loc: S.W. Wisconsin
Its kind of a"If the shoe fits"thing.I like the KISS rule otherwise.Keep It Simple Stupid LOL. Have fun, thats the key!!!


Edited by mikeyg (05/30/11 11:30 PM)
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#1926790 - 05/30/11 11:48 PM Re: Sizing Die setup for an AR-15 [Re: fw707]
SDCoyoteCaller Offline
Die Hard Member II

Registered: 05/10/01
Posts: 1772
Loc: South Dakota
Originally Posted By: fw707
Originally Posted By: SDCoyoteCaller
Maybe I am overthinking all this, also. Thanks.


You're not overthinking it. You're applying bolt gun methods to a semi-auto gun.
The body of the case needs to be sized back to function in the AR chamber.
If the case is a little too long in a bolt gun, the bolt won't close and you'll know you've got a problem. If the case is a little too long or the base hasn't been sized back smaller than chamber dimensions in the AR, you have a possibility of the case sticking in the chamber before it seats fully, and you can have the round fire out of battery. Then you'll know you have a BIG problem.
If you're lucky, the round won't fire, but the force of the bolt will have stuck the oversize case so tight in the chamber that you'll have to drive the live round out from the muzzle end.

Full length sizing is the only way to go for an AR. Some folks even go so far as to use small base dies for a little extra squeeze.


FW707,

This is exactly why I am asking. To avoid that situation. I may not be asking my question correctly. I should clarify that the way I set my die up currently is with it screwed in to touch the shellholder and then a bit more so the press cams over a bit. Based off of once fired Lake City brass, this sets the shoulder back .002" for brass shot in my bolt gun and .005" for brass shot from my AR. I understand what your saying, but I do think I am fully resizing my brass all the way to the base and not partial resizing. Like I said, the press does cam over a bit at the bottom stroke, so the brass is fully entering the die. I guess I just want to make sure I am squeezing it down enough to avoid the very problem you described above. The last thing I want is for the rifle to go off when out of battery. Thanks.
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#1926794 - 05/31/11 12:04 AM Re: Sizing Die setup for an AR-15 [Re: SDCoyoteCaller]
fw707 Offline
Moderator

Registered: 03/18/09
Posts: 5809
Loc: Up a Holler in KY
Originally Posted By: SDCoyoteCaller
I should clarify that the way I set my die up currently is with it screwed in to touch the shellholder and then a bit more so the press cams over a bit.


Yep, as long as it's a full length sizing die you're good to go. thumbup1

I've always thought of "bumping the shoulder back" as a completely different process done with a neck sizing die. I've never measured the shoulder set back after FL sizing.

Old folks like me get confused after 8 PM. laugh
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If a man has a watch, he will always know what time it is.
If he has two watches, he will never be quite sure.

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#1926796 - 05/31/11 12:16 AM Re: Sizing Die setup for an AR-15 [Re: fw707]
SDCoyoteCaller Offline
Die Hard Member II

Registered: 05/10/01
Posts: 1772
Loc: South Dakota
Awesome...thanks a bunch for the help. I have been a die hard bolt man, and resisted the temptation to get an AR. I finally broke down and got my first about a year ago, which was a JSE "cheap" upper mated with a Plum Crazy lower. I recently added a DPMS Prairie Panther to my arsenal about a month ago. To say I have been bitten hard by the black gun bug, would be a gross understatement. I was a little leary about reloading for them at first, but am feeling much more comfortable now. Thanks alot for your help. I know slam fires can also be an issue. I read on 6mmBR.com that the Rem 7 1/2 primer was good to use and had a thicker cup to reduce slam fires. I bought some of these to try. What are your thoughts on primers?
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#1926803 - 05/31/11 12:39 AM Re: Sizing Die setup for an AR-15 [Re: SDCoyoteCaller]
fw707 Offline
Moderator

Registered: 03/18/09
Posts: 5809
Loc: Up a Holler in KY
Somebody makes a "military" grade primer with a harder cup, but I don't remember who it is.
I always tried to load the first round from the magazine. That reduces the force of the bolt hitting the case. Dropping a round in the chamber and then dropping the bolt on it is a big no-no from the rumors I've heard.

Try some Benchmark and a 55 Sierra HP and see how it works out for you. It's tough on yotes. thumbup1
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If a man has a watch, he will always know what time it is.
If he has two watches, he will never be quite sure.

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#1926809 - 05/31/11 12:54 AM Re: Sizing Die setup for an AR-15 [Re: SDCoyoteCaller]
Jack Roberts Offline
Admin/moderator

Registered: 05/10/01
Posts: 15815
Loc: Elko, NV formerly MD
You are on the right track. You need to measure the shoulder setback. Even for an AR .002 is about perfect. .005 is way too much and will cause head separations in as few as 4 firings.

I aim for .001-.002 for a bolt and .0015-.0025 for a self loader.

Jack
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"Yeah, to where the going's easier." Ben Bova

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#1926815 - 05/31/11 01:07 AM Re: Sizing Die setup for an AR-15 [Re: SDCoyoteCaller]
hylander Offline
Die Hard Member II

Registered: 01/09/04
Posts: 1033
Loc: California
Quote:
I read on 6mmBR.com that the Rem 7 1/2 primer was good to use and had a thicker cup to reduce slam fires. I bought some of these to try. What are your thoughts on primers?


I prefer:
Rem. 7 1/2
CCI 400
CCi 450

As these have a thicker harder Cup.

I have had primers peirced with
Fed. GM205M and Win. WSR primers
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#1926823 - 05/31/11 01:44 AM Re: Sizing Die setup for an AR-15 [Re: SDCoyoteCaller]
ninehorses Online
Die Hard Member II

Registered: 11/18/01
Posts: 1729
Loc: Mason,Tx,U.S.A.
In .223, Federal 205's, Imr-4895, Nosler 55bt.
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Rifles are like women, every one is different!

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#1926846 - 05/31/11 04:30 AM Re: Sizing Die setup for an AR-15 [Re: ninehorses]
unloaded Offline
Die Hard Member II

Registered: 12/03/06
Posts: 1905
Loc: SW Indiana
Here's a good read on setting up your die:
http://www.predatorxtreme-digital.com/predatorx/201104#pg19

It applies to bolt and semi guns. Just make sure the fired brass you use to set it is from the gun that will be shooting it. This is for doing it without the headspace gauge. Most guys are setting the shoulders back way too far like Jack says. Shortening brass life and causing them to need trimmed way more than they should.

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