View Full Version : brass expansion in factory barrels
Do I need to worry about web expansion weakening the brass and having a possible blow out?, or can I resize and forget it, I think its dangerous, but want more insight on this matter please. I really want to hot rod these bullets but I am afraid of a catastrophic failure, please advise me on this matter..
Thank you all..
By factory barrel, I assume you are referring to Glock.
I have loaded and shot thousands of rounds through my stock barrel (Gen 3 G20) and have never had a failure. I practice good loading practices and don't shoot max pressure loads more than once - and only in new brass. Some folks will shoot two to three rounds at hot pressures, but I tend to be pretty conservative.
I full length resize and relegate spent brass from full-house loads to the practice assortment. In my practice assortment I have only found one split, and that was a nickel-plated Remington that split when re-sizing. Other than that one exception, cases have been retired because they eventually shrink below minimum specs. That seems to be the limit on case life for me. My practice/IDPA loads are 180 gr @ 1050 fps (about like a near max .40). I carefully inspect and measure each case after re-sizing. I have had fine results.
In some situations with the Glock barrels, the infamous "Glock Smile" rears its ugly head. I would not re-use any brass exhibiting such signs. A smile indicates that there is a pretty sizable stretching (and weakening I imagine). A bit of a hog belly bulge is normal for a Glock barrel. I only recently encountered smilies in my own gun. I had previously shot plenty of hot stuff and never seen one. They cropped up when using 800X powder and 180gr + projectiles. I don't load 800X and heavy projectiles for this reason. A9, A7, and Blue Dot have worked great. 800X is awesome behind 135 grainers though. Also the loads from our favority 10mm ammo manufacturers have been fine too.
In my experience, use good handloading practices and only load the hot stuff in new brass. I have had great results.
You need to read a couple of the sticky threads here that describe how to load safely, how the hot loads are approached, and that no one else nor this website are libel for you trying something that you're not skilled or following the directions described. For some reason the tone of your post gives me the impression you want to go "hot" without taking all of the time and effort of doing careful work-ups. I could be wrong, so my apologies if I'm busting your chops inappropriately here, but if I'm right, it's better that than blowing up your gun and picking shrapnel out of your hand/arms/face... :shocked:
The short answer to your question is - the Glock barrel has looser dimensions than the custom barrels, and therefore, max loads will be reached quicker in the load development cycle (and therefore at a lower velocity level) than with a custom barrel. Going too far in the factory barrel leads to the Glock Smilies you allude to.
If you push your brass to that point without slow, careful load work-up, I agree that you should trash that brass. If you work up slowly, you'll see the bulge starting before it gets horribly bad. That's the point you should stop at. (Actually, if you're using the techniques taught here, you'll never get to that point...) I still relegate that brass to the pile that I shoot lighter loads with, but it's not unsafe to reload.
I believe it's Redding, but it could have been another company, just put out a die designed to iron out the Glock Smilie on 40S&W brass. (And, of course, it works on 10mm as well.) Personally, I think this is meant only for the slightly swollen brass, and NOT the ones that have full-blown smilies with a pinched area where the smilie meets the case wall.
I handload many cartridges and gunsmith, so I know the horros of negligent handloading, and the destruction it can do to guns "but never mine..lol" so yes I am very cautious, but manted to get an approximate baseline, and a better understanding of the behavior of brass in a glock chamber, I am used to 1911 stle pistols, which have a tighter chamber from the factory, although I appreciate the loser dimensions which allow the weapon to be more reliable "same idea behind the AK".
I have not got the smile yet but I have started to get potbellys with 180gr at 1150fps-1200fps, it is a small buldge but I understand that this can stress and weaken the web, so I guess more accurate of a question is, have people had this expansion but still continued to load that specific brass at that same level of pressure and that brass not have a faliure, and how many times has it been reloaded, my understanding of brass and reloading, lends me to be fearful of reloading this specific piece of brass again for fear of a failure..
Makeminea10mm I found your answer to be very helpful and thank you greatly for the insight..
OP, You are right to be wary of the extra bulge that you find with your stock barrel. It is a limitation to case life an pressure maxes relative to some other chambers. The extra stretching does weaken brass. When I work up in small increments, I make careful measurements of the "bulge" and compare it to some reference measurements. As I stated before, I do not load hot pressures more than once. But to your original question, you can get some pretty high performance from your stock barrel - with careful practices.
I always load hot loads with Starline brass, so over time I have developed some fairly reasonable benchmarks. The largest case expansion for loads at starting pressures measure about .431 to .4315. Mid-range loads measure about .432- .433. A Buffalo Bore factory load (Starline Brass) approaches .434" max exansion. .434" seems to be at maximum pressures. When working up, I tend to level off when case expansion measures about .4335" at the very top end, but usually less. Of course, I carefully watch for other indications of excess pressure as well.
My strategy is not as rigorous as, say, the Ken Waters method, but it gives me reasonable assurances. I also don't load "off charts." I stick with published data if available. I tend to work up to published maxes and then settle on a final load that is backed off a bit from published maxes. The 10mm performs plenty well within published limits. Your results may vary, but my chronied velocities typically exceed those of published data.
As you work up during load development you'll notice a pattern in case measurements. If you load with Starline, you may consider buying some Buffalo Bore factory loads to use as a reference point. They will be at or near max pressure. This is not foolproof by any means, but it can provide a useful benchmark.
MMA10 has some fantastic insight and I have benefited from his suggestions. I suggest doing a search for posts that he's made about the Ken Waters method and any others that relate to pressures. I agree that one should not try to "iron out" any Glock smiles. Those cases should be tossed.
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