AR Barrel Chamber Question??

[5.56Geo]

Thanks guys for the help!

Let me mention a few things I have done since I started this thread;
1. Checked my AR chamber against my sons AR with a sized empty case. I only checked visibly wiggling the brass with a dental pick in the primer pocket. They both seemed the same in allowable movement

2. I checked every case from this batch of brass and found 5 suspect pieces of brass.

3.. I went to the range last night and shot 120 round of factory ammo without any issues. Most of what I shot was the Wally World 30pack of QZ1 stuff and 20 rounds of Winchester hunting ammo.

4. Checked my dies to check the relation/position of the shell holder to the die in the most upward position. It not only touches but "Cams-over" quite a bit. (after reading opsoff1 comment I may be over sizing the brass and causing a HS issue).

I am leaving to Alaska for work this morning and will be back on Friday 8/29/14 to continue to fix this problem.

Here are some things I will do while I'm gone;
1. Buy a new set of dies. What brand would you guys recommend? ...RCBS FL Dies(green box)?

2. Buy a .223/5.56 go- no go gauge.

3. Measure a sized case (at the current die setting) against a fired case from my AR to see how much it's expanding. -EDIT added this idea.

If you guys have any other recommendations please let me know. Thanks -5.56Geo

[5.56Geo]

@ lunchbox;

I'm not sure if it is MG brass, I have also heard that MG's beat up the brass. This is (.223 and 5.56) mixed head stamp brass, "range pick up" that I bought a few months back when brass was hard to come by. I'm also not sure of many time its been fired. I noticed about half+ that had the sizing ring at the bottom of the case indicating they have been reloaded at least once. Maybe some one just dumped/left some brass at the end of it's life.

[mpom]

The Comparator is worth buying, as it lets you measure the actual "bump", that is, the amount you are pushing the shoulder back. the ovecamming tells me you are bumping the shoulder way too much. any of the regular full length dies will work but precision fanatics seem to like Forester Hornady Redding, mostly because of supposed better concentricity between case and bullet and because of micro adjustable seating depth stem. unless you are a benchrester, any should be good. do recommend a floating carbide neck expander, which eliminates need to lube inside of neck.
dont think you need to purchase a Min HS gauge for the issue you are having, as factory ammo serves that purpose.

[Heavy Metal]

If it's not doing it with factory ammo, don't worry.

Looks like SAW Brass to me.

[lunchbox]

@ lunchbox;

I'm not sure if it is MG brass, I have also heard that MG's beat up the brass. This is (.223 and 5.56) mixed head stamp brass, "range pick up" that I bought a few months back when brass was hard to come by. I'm also not sure of many time its been fired. I noticed about half+ that had the sizing ring at the bottom of the case indicating they have been reloaded at least once. Maybe some one just dumped/left some brass at the end of it's life.

It was just a thought. Say if it turns out to be MG brass in combination with HS/resizing issue, might be leading to case failure. Not one thing but combination of things. Hope you get it figured out and be safe!

[Onyx Z]

Here are some things I will do while I'm gone;
1. Buy a new set of dies. What brand would you guys recommend? ...RCBS FL Dies(green box)?

Any FL dies should work, but I really like the Forster benchrest set. Unlike some of the cheaper brands, the seating die holds the the case in perfect alignment as the bullet is seated to prevent bullet runout.

Of course you could always get just a FL sizing die and continue using your current seating die if you want to save a little money.

[markm]

First... Do you have a case gauge? This is a simple, no-brainer way to tell if your sizing die is set up right. I'm suspecting that this is a die setting issue.

You should be able to FEEL that you're really squeezing the brass back down a lot if it were some blown out M249 brass. Press FEEL is more valuable than any die set, comparitor, or any other gizmo.

[opsoff1]

Let me mention a few things I have done since I started this thread;
1. Checked my AR chamber against my sons AR with a sized empty case. I only checked visibly wiggling the brass with a dental pick in the primer pocket. They both seemed the same in allowable movement

This truly won't tell you anything - this is a game of thousandths - don't waste your time.

2I checked every case from this batch of brass and found 5 suspect pieces of brass.

Suspect in what way?

3.. I went to the range last night and shot 120 round of factory ammo without any issues. Most of what I shot was the Wally World 30pack of QZ1 stuff and 20 rounds of Winchester hunting ammo.

Good indicator that the issue resides in the brass that you have.

4. Checked my dies to check the relation/position of the shell holder to the die in the most upward position. It not only touches but "Cams-over" quite a bit. (after reading opsoff1 comment I may be over sizing the brass and causing a HS issue).

Red flag here - standard dies use a 7/8 x 14 thread - very coarse and a small movement can make a big difference in sizing / bumping the shoulder. A case gauge would really be the hot ticket right about now. Bear in mind that a 14 pitch thread will move your die up/down .071" per revolution - or every 10 degrees move it up/down .002. 10 degrees on the diameter of the die (where the threads are) equals a movement of about .076" or a little more than a 1/16 of an inch - get my point?

Here are some things I will do while I'm gone;
1. Buy a new set of dies. What brand would you guys recommend? ...RCBS FL Dies(green box)?

If you are not after precision (read benchrest type accuracy) then any of the standard big mfr's will be fine - stay away from small base dies. Use a standard 223 Rem by Forster, Redding or RCBS.

2. Buy a .223/5.56 go- no go gauge.

This won't tell you your exact head space, but it will tell you if it is within the specified limits.
Invest in a case gauge too - worth their weight in gold - also see # 4 above - the gauge keeps you honest.

3. Measure a sized case (at the current die setting) against a fired case from my AR to see how much it's expanding. -EDIT added this idea.

How are you going to measure this? See #2 above.

[sinister]

A Stoney Point / Hornady gage and micrometer calipers will tell you if you are bumping your shoulders sufficiently and not excessively -- .002" is enough. .003" or more risks case wall thinning and eventual separations. You want to make sure your reloads fit in all your rifles.

This happens when you bump the shoulders excessively:



A drop-in case gage will tell you if your cases fall within minimum and maximum length and bump, but not by how much.

Military chambers (especially for automatic weapons and/or worn guns) may start out longer than commercial chambers (example is 7.62 vice .308 Win):



I like small base dies. OPSOFF did me a great favor many, many years ago when I went to Camp Perry with cartridges first-fired in random military chambers, sized in RCBS full-length dies, and loaded for a tight-chambered Douglas-Merchant-Brownells National Match M16/AR barrel. Bottom line they wouldn't fit in my match rifle's chamber. This is especially important if shooting range pick-up brass in SAAMI or tight commercial or match chambers.

[markm]

Yeah... I've run God knows how many rounds through my Dillon Carbide die, and it's small base. Never a problem.