Resizing brass problem

[Sespe]

I was full-length resizing some 300 Blackout brass tonight and had 3 problem cases. 2 were extremely hard to size, one wouldn't even size all the way.

The two that were difficult left a slight cut ring of brass around the case.

RCBS die set
Left piece of brass would not go all the way in. 1x fired .223 brass headstamped "AAC", cut and sized using this die, then fired as 300 Blk.
Other 2 pieces are commercial PNW Arms 300 BLK Range, 147gr FMJ BT. The other 38 pieces of this brass formed just fine.

I'm using Frankford Arsenal spray lube, a couple shots in a big ziploc baggie and tumbling the brass around.

What am I doing wrong?

 

[Boltfluter]

Re: Resizing brass problem

Was this brass fired in a different rifle before being sized for your rifle?. Looks like the chamber is oversized at the back end. Hard to tell but it looks like you have several head seperations? Just a thought.

Regards, Paul

 

[Sespe]

Re: Resizing brass problem

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bolt fluter</div><div class="ubbcode-body">Was this brass fired in a different rifle before being sized for your rifle?. Looks like the chamber is oversized at the back end. Hard to tell but it looks like you have several head seperations? Just a thought.

Regards, Paul </div></div>

No, fired in this rifle only. Several other cases had slight bulges in the area, but all resized fine. This is a new-to-me barrel bought used through another forum.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">"SI Defense 300 AAC Barrel. 1/8 Twist. 200 rounds through it. Shoots tiny little groups. Excellent condition."</div></div>

What are my options for checking the chamber?

 

[244]

Re: Resizing brass problem

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Sespe</div><div class="ubbcode-body">What are my options for checking the chamber? </div></div>

If you have any unsized brass you can measure the case, especially near the base, against the reamer specs. The brass case will contract slightly after firing to allow extraction of the case. I'm sure someone will know exactly how much the brass contracts after firing.

 

[mavrick]

Re: Resizing brass problem

You might try some new lube. I know I had some hydrlic denting from some spray lube I switched to imperial sizing wax and its worked great. But I think you might have more issues but its worth a try. Dustin

 

[milo 2.0]

Re: Resizing brass problem

I'd be getting ahold of the guy that sold you the barrel!
You sir, have a mess.

 

[seanhagerty]

Re: Resizing brass problem

I agree about the lube issue. Get a better lube and I bet you dont have this trouble again.

 

[Boltfluter]

Re: Resizing brass problem

I would measure an un-fired round against a fired case at the base on both. Spring back is usually only about .001. Almost looks like there is a step in the chamber at the rear. I would not shoot this stick until this is squared away. If you can look into the back of the chamber, you may be able to see a step in the chamber.

Regards, Paul

 

[BK7saum]

Re: Resizing brass problem

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Sespe</div><div class="ubbcode-body"> <span style="text-decoration: underline">1x fired .223 brass headstamped "AAC", cut and sized using this die</span>, then fired as 300 Blk.
Other 2 pieces are commercial PNW Arms 300 BLK Range, 147gr FMJ BT. The other 38 pieces of this brass formed just fine.

I'm using Frankford Arsenal spray lube, a couple shots in a big ziploc baggie and tumbling the brass around.

What am I doing wrong? </div></div>

You say that it is 1x fired 223 brass, then you say that it has only been fired in your rifle. Which is it?

Also are these photos after the initial sizing and before shooting through the BLK chamber?

Or are these photos taken of sizing the cases after shooting in the 300 BLK chamber?

Looks to me like you are cutting down .223 brass to 300 BLK. If so, and using once-fired .223 brass, your problem is a common one. The brass was previously fired in a .223 with a generous chamber, thus the rear of the cartridge has expanded to a size larger than your FL sizing die. That and lack of a good lube is causing difficulty in sizing. If your sizing die has a sharp corner and no chamfer leading into the body of the die, that is contributing to the ring of brass being pushed down the outside of the case.

A better case lube like the imperial will/should take care of the difficulty in resizing, but might not depending on how oversize this cut-down .223 brass is.

If I'm mistaken, then I stand corrected. If the conversion from .223 to BLK went okay and these are being sized post-shooting through the BLK chamber, then it looks like the BLK chamber is oversized. I still think a better lube or application of more lube will help your sizing issue.

Try a different lube, properly applied, and let us know if the issue is still present, less of a problem, or goes away.

Brad

 

[Sespe]

Re: Resizing brass problem

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BLK7</div><div class="ubbcode-body">
You say that it is 1x fired 223 brass, then you say that it has only been fired in your rifle. Which is it?

Also are these photos after the initial sizing and before shooting through the BLK chamber?

Or are these photos taken of sizing the cases after shooting in the 300 BLK chamber?

Looks to me like you are cutting down .223 brass to 300 BLK. If so, and using once-fired .223 brass, your problem is a common one. The brass was previously fired in a .223 with a generous chamber, thus the rear of the cartridge has expanded to a size larger than your FL sizing die. That and lack of a good lube is causing difficulty in sizing. If your sizing die has a sharp corner and no chamfer leading into the body of the die, that is contributing to the ring of brass being pushed down the outside of the case.

A better case lube like the imperial will/should take care of the difficulty in resizing, but might not depending on how oversize this cut-down .223 brass is.

If I'm mistaken, then I stand corrected. If the conversion from .223 to BLK went okay and these are being sized post-shooting through the BLK chamber, then it looks like the BLK chamber is oversized. I still think a better lube or application of more lube will help your sizing issue.

Try a different lube, properly applied, and let us know if the issue is still present, less of a problem, or goes away.

Brad

</div></div>

Sorry, let me clarify. Only the cartridge on the left is twice fired. Once as a .223 then cut down and run through this same die. Then loaded and fired in the 300 Blk barrel. I did 25 cases that way, all extremely easy with no problems. This is the only fired one quite that bad. Out of the 60 rounds, I find 3 other that have a slightly visible bulge at the same point. 2 are the commercial rounds, 1 more is my conversion.

The other 2 cases were commercial-bought 300 Blk rounds from the start, fired once.

 

[buffybuster]

Re: Resizing brass problem

Imperial Sizing Die Wax..... Dollars to Donuts, that will solve your problem.

 

[Force_Multiplier]

Re: Resizing brass problem

if I'm following... all these cases were fine, 1 was once fired as a 223, converted to 300blk, 2 were new 300blk, they were all loaded then fired in your chamber, then these 3 wouldn't resize correctly and a few more had bulges....


I'd say your chamber is crap and that's why it was for sale in the first place

 

[Sespe]

Re: Resizing brass problem

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Force_Multiplier</div><div class="ubbcode-body">if I'm following... all these cases were fine, 1 was once fired as a 223, converted to 300blk, 2 were new 300blk, they were all loaded then fired in your chamber, then these 3 wouldn't resize correctly and a few more had bulges....


I'd say your chamber is crap and that's why it was for sale in the first place </div></div>

Aww, shit. That is starting to become a consensus...

At least the seller is local.

 

[former naval person]

Re: Resizing brass problem

Maybe the chamber is at fault...but, check your sizing die. Your shaving is being done by the mouth of the die...the edge of the mouth shouldn't be that sharp. There usually is a tiny bevel at the entrance to the die. If it is extremely sharp that could be the origin of the shavings. Dies are supposed to ssquueeze the case...not cut them down to size!

 

[JeffP40]

Re: Resizing brass problem

I saw an issue with an autoloading pistol about 30 years ago. It was a 38spec made for targets. I noticed the brass had a bulge on one side after firing. After the owner had it checked, it was determined that the slide was opening before the pressure had subsided sufficiently, and was putting too much pressure on the unsupported part of the case upon extraction. I wonder if that is what is happening with yours? that would explain the bulge on one side of some. I am assuming you are using an ar platform? Just a guess. I agree with the lube ideas, although solving the potential timing problem is higher priority.

 

[milo 2.0]

Re: Resizing brass problem

No amount of lube, or the quality of it will prevent this.

Your chamber is oversized, when you run your brass up into the die, it is being constricted, and has no where to go but toward the case head, hence the crinkling.
You can plainly see the case head seperation, because of the ovesize chamber, the unsuppoted chamber is letting the brass blow out.
If you measure a sized, unshot case, then measure a fired one, if the difference is ".006" or greater, the number might be closer to ".004", your chamber is screwed.
Your fired brass needs to be thrown.
And if you keep shooting this gun, being a semiauto, the chances of getting hot brass in your hand or face is likely.
For your sake, I hope I'm wrong, but get this to a smith and check it out.

 

[Sespe]

Re: Resizing brass problem

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: milo-2</div><div class="ubbcode-body">No amount of lube, or the quality of it will prevent this.

Your chamber is oversized, when you run your brass up into the die, it is being constricted, and has no where to go but toward the case head, hence the crinkling.
You can plainly see the case head seperation, because of the ovesize chamber, the unsuppoted chamber is letting the brass blow out.
If you measure a sized, unshot case, then measure a fired one, if the difference is ".006" or greater, the number might be closer to ".004", your chamber is screwed.
Your fired brass needs to be thrown.
And if you keep shooting this gun, being a semiauto, the chances of getting hot brass in your hand or face is likely.
For your sake, I hope I'm wrong, but get this to a smith and check it out. </div></div>

But wouldn't I expect to see this on all my cases? Why only a few of them?

 

[milo 2.0]

Re: Resizing brass problem

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Sespe</div><div class="ubbcode-body">
But wouldn't I expect to see this on all my cases? Why only a few of them? </div></div>

You are right, I most likely didn't read your post thoroughly.
I apologize. But the pics posted are from oversize chamber, or excessive headspace in the case head seperations.

Like I said measure sized and fired cases, if alot, get ahold of a smith on here and ask!
Maybe the brass that is cracking is older, more firings, case hardened?

 

[milo 2.0]

Re: Resizing brass problem

Sespe,
I'm no gunsmith, maybe I shouldn't have been so "matter of factly" in my post.
The case on the right in your pic, I've seen that right here in my garage. It was once fired 6.5x47 lapua brass,I had to shit can 265 pieces because of oversize chamber, it hurt. My cases were expanding ".008" from new unfired.

Like I said, I hope I'm wrong, please keep us posted on your results.

 

[Sespe]

Re: Resizing brass problem

Okay, so I found 2 fired rounds that had ejected right into my bag. They both measure .3780 at the base. A resized case measures .3740

Too much?

 

[milo 2.0]

Re: Resizing brass problem

I say yes, but a smith would be a more reliable source than myself.