I was reloading some 10mm brass so I could shoot my new Delta Elite some more when the ram would not go all the way up to the die.  This was brass that had been previously run through this gun once before.

Pulling the brass out I noticed a bit of an issue:



I have to admit that in 20+ years of reloading with probably a hundred thousand or more rounds loaded and numerous "shoot until failure" tests, this is the first time I have encountered this.  I've seen bulges on one side from shooting through a Glock stock barrel, but these rings go all the way around.  

This load is 8.4gr HS-6 under a180gr  Ranier Plated bullet, squarely in the middle of Hodgdon's charts, and this is loading number 8 for this brass with that load.  The brass is some Russian headstamp, looks like "nny".  Not all did it, but I found 5 out of the 8 I shot that had it.


What say you, think it'll buff out?  Seriously, is this something that is common in 1911s?  Is there a timing issue that is off?  I know next to nothing about 1911s.  I do know the gun appeared to be in battery when it fired as after I saw this I ran another magazine through and checked the gun before each shot.

This may be the issue.  Left to right:  Glock 20 stock barrel, LWD 10mm Glock barrel, Colt Delta Elite barrel.

I just checked my Colt, Delta Elite and the brass case seems to be much better supported in mine than the one in your picture but then it's a Bar-Sto barrel. I didn't check my stock barrel, I'll have to find it first and check it.
I've never had case bulging like that, that I can ever remember, not even in my blow-back 10mm carbine.
What do your primers look like? First thought is far too high pressure but maybe not.
Do you have a dual recoil spring in it or just a single spring?
Here's a picture (poor focus) of my stock Delta barrel and I've never had a problem with it.
It looks like yours is cut away a lot more than mine.

Thanks flightsimmer.  The primers are fine, this load is a medium power load and one I've used for several years in all of my other 10mm guns.  Right now I'm leaning towards a brass issue combined with much less support than the Glock or LWD barrels.  Someone on another forum suggested I send the pics to Colt which I'm going to do once I talk to them on Monday.  Meanwhile I'm going to run some new Starline brass through it and load and shoot one several times to see if that replicates the problem.  If Colt tells me this is normal and to not run reloads through it, it looks like this will be a gun that cannot handle heavy 10mm loads.

I'll report back when I hear from Colt.

Uh what bullet weight? Does this happen with other headstamps?

I would say over-pressure.

180gr.  This is a load I've used in every 10mm I own (several) and never had an issue, it's listed in the middle of the range on Hodgdon's website and it chronies well and the primer shows no pressure signs so the load itself is not overpressure.  

Update:  Yesterday evening I carefully reassembled the gun step by step according to the instructions.  Yes, I had read the instructions before I shot the gun the first time but since they cover several different models of gun it wasn't terribly clear, and even doing it again step by step it still wasn't clear.

This afternoon I took a piece of once fired Federal brass and proceeded to load and shoot it.  I got bored after 40 loadings and no issues.  I decided to take one of the suspect batch of Russian brass that had already had 8 loadings and proceeded to reload it until at firing number 20 it still hadn't failed.  So then I took ten of the 8 times loaded brass and shot them each one more time with no issues and picked a couple that looked like they might be a bit off and loaded them a couple more times with no issues.

So, I feel reasonably confident it wasn't a brass issue but a gun issue related to improper reassembly affecting the timing.

1911 gurus, what do you think?  If the slide stop hadn't recaptured the barrel link when I reassembled might that have cause it to unlock early?  The only other thing I can think of is the springs somehow didn't get seated but every scenario I can think of there makes the spring action stiffer not softer.

shibumiseeker: I have Delta Gold Cup, and I never any problems you described. In my mind there is only one way to reassemble a 1911, and it either works or it doesn't.

Personally, I would just toss the Ruskie cases.

I shot all kinds of brass that I picked up from the range, and my main brass is from Starline. I am usng Unique powder.

Are you using the factory inner/outer recoil spring and plastic plug? I am using the 10mm kit from Kings Guns Works, Glendale, Calif. It comes with a Wolff single spring, 2 shock buffs, & full-lenght guide rod.

Problem Solved:

I have managed to reliably replicate the problem.

It is a combination of lower chamber support, weaker brass, and bullet setback due to recoil and/or chambering because of some rounds having less crimp due to changes in brass characteristics.

The experiment:

10 rounds of the 8x fired nny brass with the load listed in the OP (my standard plinking load) Federal 150 primers (not noted in the OP). I noted carefully which ones seemed to have less resistance to the bullet seating. All seemed to have the same feel in the Lee FCD.

Set the chrony up.

Measured the OAL, loaded one full magazine. Chambered one round, shot it. #1 was 1029fps, within my normal range for my plinking loads. Looked at the magazine. The next in line (top of the magazine, round number 3) had excessive setback, like only the tip of the bullet showing out of the brass.

Shot #2 at 1051fps. #1 and #2 had normal looking brass.

#3 shot with a little more felt recoil and 1125fps. Looked at the brass and saw the bulge pictured in the OP. The primer showed a little more pressure but certainly not excessive and well within what I consider normal for a medium load.

All the remaining bullets were showing signs of some setback, varying from a few thousandths to maybe 15 thousandths.

#4 shot at 1078fps with no bulge.

I ejected #5 before firing and saw the bullet set very far back like #3. It shot at 1143fps, but had no bulge and the primer looked similar to #3, but again, not excessive flattening.

#6 was 1097fps and had a bulge.

#7 was 1065 no bulge.
#8 was 1057 no bulge.
#9 was 1048 no bulge.

I think I found my culprit.

But because I am a scientist and an engineer, this study would not be complete without further failure mode analysis. So I took 10 more rounds of the 8x loaded nny brass and reloaded it.

I loaded these into my Glock 20 with the stock barrel (the one on the left pictured up there), shot two and inspected the remaining ones. None had more than a couple thousandths setback. Shot the remaining magazine and all 10 were somewhere between 1040 and 1060fps which is what I have measured for many years with this load.

Loaded 10 more and repeated the above with the LWD barrel in the Glock. Identical results.

So now I wanted to see what running it a little hotter would do so I loaded 3 of the 8x fired brass and pushed the bullets back until they contacted the powder which put it at the same OAL as the ones that bulged above in the Colt.

Fired all three through the Glock20 with the LWD barrel. 1139, 1155 and 1136fps. No bulge, primers looked about the same as the ones in the bulged brass in the Colt.

So now we have to compare brass. Took 5 once fired nny brass and deliberately loaded it with the excessive bullet setback. Shot all five through the Colt. Same results as the first round of firing through the Colt, 3 had bulges not all correlated with the highest velocities. Lowest was 1123fps and highest was 1145fps. Primers still fine.

Now the moment of truth: Took 5 new Starline brass and loaded it and pushed the bullets back until it met the powder so it had the excessive bullet setback. Shot all five through the Colt. No bulges at all, primers looked fine. Velocities were 1131 for the lowest and 1150 for the highest.

As an added bit of fun, took 9 rounds of the once fired nny brass, loaded normally then loaded the Colt and shot a couple of rounds. Measured the remaining rounds, maximum setback was .002", most were less than .001". Fired the remaining magazine. For the entire string the range was 1035-1057fps. Loaded one more and chambered it ten times. Setback was .003"

Repeated this with 9 rounds of new Starline brass, no setback greater than .001" was noted after the first two shots and the range for the entire string was 1033-1049fps. Loaded one more and chambered it ten times and setback was .002".

Just for giggles, I loaded two more of the Starline lot and chambered them one each ten times with the stock Glock barrel and the LWD Glock barrel and setback on each was less than .001".

Conclusions:

The nny brass has less web support and less quality control than the Starline. Combine this with less chamber support makes it more likely to bulge as pressure rises. Add to that a tendency for the feed geometry and recoil of the Colt to increase the likelyhood of bullet setback. Multiple times fired brass is less consistent so a crimp that was fine with newer brass led to some bullets setting back.

I now trust my Colt again. I am going to run some of my warmer rounds loaded in new Starline brass (chronying ~1180fps through my Glock) and see how it fares, then increase the powder in .1gr increments until I start seeing brass bulging or other pressure signs. I am NOT going to try any of my nuclear 10mm loads I run through my Glock with the LWD barrel in this Colt.

And just for your fun I found this:

And thanks to everyone who made meaningful suggestions.

Thanks for taking the time to write up the analysis, that was really interesting. My original assessment of the case was correct. Goes to show that not all cases are the same.

Years ago, I had the some problems with NNY 223Rem/5.56NATO cases, I can pop out the spent primer no problem, but reseating the new primer was a pain, I ended up crushing a few new primers several times. After that, I learned my lesson, I would just cull those nasty NNY cases out for recycle.