Check Out my 10mm Case and Primer

S

Swifty Morgan

New member
I made a bunch of 10mm defensive rounds for my Glock 20, and I am looking to get educated on case inspection.

I fired two rounds from a Glock 29 with a stock barrel. About 3/16" up from the rims, the cases are now expanded from about 0.420" to about 0.433". The primers are flat with the bottoms of the cases. There are marks from the firing pin hole on the primers. I will post photos.

Does this look normal for this caliber and pistol? I've read that aftermarket barrels provide better support. I don't plan on reloading for self-defense, but I was hoping I could reuse the brass for target loads.

I haven't chronographed the loads yet.

The recipe is from Speer. I did not have CCI primers, so I'm using Wolf. The brass is new Starline.

1.250" OAL
10.7 grains Blue Dot
.400" 180-grain Gold Dot
Wolf Primer

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I dug up a Hornady factory round (the opposite of hot) and compared. The Hornady is bulged out to 0.433" and also has a rectangular impression around the firing pin mark, but the firing pin mark is slightly smaller. The Hornady was fired from a Glock 20.
 
The Glock rectangle.... par for the course.

The Glock firing pin drag mark, again par for the course.

The primer still has well rounded edges. Flattened means that the primer is flat all the way across the primer pocket.

You are still in 'safe' territory.
 
I appreciate the help. I already made 100 of these, and they are impossible to pull, so I want to keep them. Hoping to get the old Chrony running tomorrow.
 
When I first started loading in the 70s, I bought Ken Waters Volume, Pet Loads. His standard recommendation on pressure was a case head expansion greater than .005 was working maximum. Expansion of .013 would raise my eyebrows. Also, Blue Dot is no longer recommended in the 41 Magnum, so I'd look at another powder.
 
I bought Ken Waters Volume, Pet Loads. His standard recommendation on pressure was a case head expansion greater than .005 was working maximum. Expansion of .013 would raise my eyebrows.
Click to expand...

If his case head was expanding that much I would agree. But his case is expanding above the head, at the unsupported portion of the Glock chamber. Nothing new from Glock.

To the OP, you may need a Lee sizer to push all of the bulge back into place. Some folks have issues with the bulge not being completely removed by a standard resizing die. The Lee bulge buster is a push through swaging die. Resize a case with the bulge and try it in your chamber before you buy the set from Lee. But it's not that expensive.
 
I recently had a thread about Using the LEE bulge buster for 40SW. I deemed .433 fiixable. .435 not. That thread is on page 2 now.
Is that a current production Glock? An old one, I would understand.
I bought a couple thou range brass and would pass that case through the buster and use it again. Your clean brass shows the bulge. My clean .435 showed a belly to naked eye.
 
I have an old 20 as well--that looks like the common but infamous "Glock smile" which occurred on the original barrels. The problem was Glock machined the feed ramp up to the chamber face such that a large part of the head of the case was unsupported on the bottom side of the barrel. To make matters worse, the chamber ID was often enlarged to the point that the cartridge was often too loose, which could potentially result in over-pressure issues (please note what I mean is overpressure on the case relative to it's support; not absolute max SAAMI pressure) if the cartridge didn't headspace properly (easy to do if you crimp it a tad much). Your brass in the picture looks to me like it's toast--toss it, because it's stretched and flowed to the point where it has a critical thinness at the top of the head, especially if you can probably see an incipient but symmetric line encircling the case. You typically won't see overpressure on the rim face or primer in that situation. The solution? aftermarket barrel with full support and snug cartridge fit. Test your loaded cartridges for proper fit (with barrel removed from gun) prior to shooting them.

I advise against doing it--but when the fit is properly supported by the chamber the gun is capable of successfully firing loads past the max SAAMI spec. without that kind of stretch.

Starline pistol brass is generally quite good (that's what I use for my 10mm hand-loads).

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ATK group makes Blazer, Speer, CCI and Federal. Their brass is notably a softer alloy among the factory ammo producers. My recommendation - buy a box of Winchester. Their brass, in my experience, tends to hold up longer. Seems both a firmer alloy as well as a thicker inner wall on the brass in general. You might also try a box of GECO from RUAG group in Europe. Many European police forces use 10MM Glocks as their side arm. - just an idea.
 
I ran a few rounds through the chronograph, and they really impressed me. One hit 1695 fps, and another reached 6639. I had no idea Blue Dot had so much pep. I expected good performance, but I never thought I'd approach Mach 6.

I wonder if changing the battery would slow the bullets down.
 
I ran a few rounds through the chronograph, and they really impressed me. One hit 1695 fps, and another reached 6639. I had no idea Blue Dot had so much pep. I expected good performance, but I never thought I'd approach Mach 6.

I wonder if changing the battery would slow the bullets down.
Click to expand...
You using a labradar by any chance? It's algorithm for processing velocities has a borderline "tripwire zone" where the pistol velocity range confuses it if the projectile is approaching rifle range velocity, usually around 1700 +/- fps. A change to rifle range velocity should do the trick.
 
I'm thinking of starting my own space program.

I put a new battery in the Chrony. Hoping it will give me accurate information today instead of making things up.
 
I don't have a Glock or a 10mm.

But when you get a bulge like that,the brass is offset relatively sharply right at the case head.

Here is my concern.If I set a piece of brass sheet in a stomp shear,and I stomp gently enough to just offset the brass,without cutting it in two,

At the metallurgical grain structure level, is my sheet brass still sound?

Does it matter if its gas pressure or a shear blade that pushes the offset?

OK,now we come along with the Bulge Buster die and re-offset tis brass....so t looks right.

I question the integrity of the brass in the locality where it is offset....twice.

I tried using Blue Dot in my 38 Super...for a little while.Till I saw something I did not like at thelockinfg surfaces of my Colt Slide and Clark barrel.

You can use Blue Dot,but I don't. Ys,I was loading a max book load That's on me,but Blue Dot might be ...is "inconsistent" the right word? I lost trust
 
Here's a barrel question.

When I look at a chambered round, it appears that the cartridge is pretty well covered, but when I fire a round, the brass comes out bulged. Is this because the chamber is wider toward the rear? If so, is this to make feeding more reliable?

I was thinking I might get an aftermarket barrel, but if it makes cartridge-feeding less reliable, forget it. That won't work for self-defense.
 
What I do is live with the minor bulging in your picture, for bulk target loads, after running them through my bulge buster.
For full power carry loads, I have a couple hundred new Starline in each caliber, just, and only, for that purpose. They will be loaded with copper HP Barnes bullets.
I do have extra barrels: G23 40 to 9mm conversion, a G19 that fits in my G26. Both barrels work fine. But I have not shot lead through any of them yet. Basicly lead is not allowed at indoor ranges; so I use Berrys played bullets.
 
If you plan from the start to reload for the guns you shoot and you know the Glock requires special handling to remove a "standard" occurence bulge, and firing pins that are not retracted when the case xtracts (I've seen the primer torn open on pics posted); why would you even consider a Glock?

I'm not a Glock hater, just never liked the duplex trigger, straighter grip angle, what I think of as ugly, coupled with the above problems, that shooters are willing to accept and work around rather than demand a fix.....I know I'm in the minority because of the proliferation of Glocks, but it's my opinion.
 
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