Reloading Problem for 10mm

[Rkerry]

I recently loaded my first 50 cartridges of 10mm using mostly Federal brass and Berry's 155-grain FMJ flat point bullets. Overall cartridge length was consistent at 1.250", per Hornady reloading specs. The brass I used was once-fired range brass in fair condition, including a six-hour tumble in crushed walnut shells to shine it up a bit. This is the same treatment I give all my reloading brass.

I tried them today in my Glock 20SF, and the cartridges performed well, cycled the action fine, and printed a very good pattern on the paper. However, the slide would lock back after the next-to-last round of each magazine was fired, and I observed that the remaining round was sitting in the magazine about 1/3" forward in the magazine, as if the previous round had dragged it forward a bit when being chambered. Therefore, with the last round forward of its intended position in the magazine, the slide would catch and remain open as if the magazine were empty. This happened on every magazine of reloaded ammo...the last round would remain in the magazine, about 1/3" forward, and the slide would lock open before loading that last round. At that point, thumbing the slide release lever would send the slide forward and chamber the last round just fine.

This problem occurred using both factory Glock 15-round magazines that came with the pistol when firing my reloads. I ran several magazines of factory ammo through and this problem did not occur once, so I am left to conclude that something about the way I loaded the ammo, or the condition of the brass, is causing the problem.

I have primarily loaded ammo for revolvers and bolts to this point, so I'm hoping that someone on this forum with experience loading for semi-autos will be able to help me figure out what I've done wrong.

[Hammerhead]

If the slide release lets the slide go forward, it's not hanging up on the round in the mag.
I would suspect recoil is causing the rounds to migrate forward in the mag.

Are your handloads on the hot side? Maybe the round moving forward is somehow activating the slide stop.

Maybe the slide stop spring is weak.

Have you have detail stripped the pistol?
Maybe the slide stop spring leg is not in the right place.

I can't think of any reason other than power level why your handloads would cause the problem.

[g.willikers]

How do the bullets you reloaded compare to the factory ones?
Shape, length, diameter, 'etc?
Just the bullets, not the complete rounds.
And how do the loaded rounds, both yours and factory, compare for overall length?
Pictures??

[Sure shot wv]

One thing that came to mind for me which may or may not help is getting rid of the flare on your case. How are you doing it? Seat and crimp in one dye or separate dyes?

[NESHOOTER]

I would 2nd kerrys post

[WESHOOT2]

More details, please; be specific:
-components
-powder and charge weight
-shooting skill level

[Rkerry]

Thanks for all the replies. Responding to a few of them...

G.Willikers: The bullets I loaded are Berry's FMJ flat-point 155-grain, .401" diameter. The factory bullets that did not exhibit the problem were PPU 180-grain round-nose JHP. COL for my loaded cartridges was 1.250" compared to 1.255" for the PPU. I have no pictures because I only loaded 50 rounds in this batch and fired them all...so I'm back to empty brass at this point.

Sure Shot: I used Hornady custom-grade 3-piece die set, and the combo seat/crimp die was used to seat the bullet and (hopefully) remove the case flare. Your comment seems like it my be going in the right direction. Do you have a preferred method to remove flare more accurately than the combo seat/crimp die? I could imagine a cartridge dragging the one beneath it forward a bit if the flare wasn't fully compressed.

WESHOOT2: Federal once-fired range brass, primed with Federal Large Pistol primers, charged with 8.2 grains of Alliant Unique (based on a recipe from the Hornady manual). Shooting skill level? Not sure where to go with that question. I don't compete, but I visit a range once or twice per week and probably fire 1,000 rounds per month, of which maybe 1/2 are my handloads. As mentioned in the original post, I've been loading revolver cartridges for a while now but have only recently begun loading 10mm, and that is the only cartridge I have loaded for semi-auto actions.

A trusted employee at the range recommended I try seating the bullets a little deeper, but he admitted that his recommendation was more of an experiment than a sure fix. I probably couldn't go more than .020" farther before I'm into the ogive more than I should be. Any thoughts on that suggestion? If I go that route, I'll probably experiment by reducing COL by 5 thousands at a time and just loading five or six cartridges at each sample depth...but I'd like to hear everyone's thoughts before I start experimenting blindly.

I appreciate any suggestions you all can provide and am excited to improve my 10mm results.

[WESHOOT2]

First thought: Test at OAL 1.260"+/-.003".

[cryogenic419]

A few things come to mind...

Are your reloaded cases clean? Smooth to the touch? Have any residue on them? How about the magazines? In good condition, no major cuts, scrapes, gouges on the followers, buildup of crud in the mag bodies, good springs?

How do your finished reload rounds measure when compared to a factory round? Are there any significant differences if you measure where the bullet is seated in the case?

Based on what I have read you are seating/crimping in one operation? If so, there may be something so minor and insignificant going on that ammo you load up for revolvers will work just fine as they don't have to feed from or into anything once they are loaded in the cylinder. When it comes to the 10mm that does have to feed from the mag, something in the seating/crimping process is causing problems. It wouldn't take much of the die crimping while the bullet is still being seated to cause some sort of problem. I would break the process down into 2 separate steps to see if that may be causing the problem.

[g.willikers]

About the only way to figure this out, is to find if it's a reloading problem or a bullet problem.
Try reloading the same cases, with the same methods, but using the same kind of bullets as the factory rounds that worked ok, instead of the ones that act up.
Don't change or do anything differently, other than the bullets.
For a small supply, just pull a few from the factory rounds.