Home Forums Hunting & Shooting Handguns Glock ammo issue

A couple weeks ago at the range I had my G 20 out with some new ammo and couldn't hit anything. Started raining and didn't have time to check it out. Went back out this weekend for some testing. This target was sprayed with the G 20 at about 20 yds. from sandbags. You can see where a couple of the bullets key holed. Before this I shot a "group" with the same ammo at about 10 yds, about 4", but all the shots went straight through. Seems the tumbling started between those two ranges. After this I switched to a different ammo and group size shrunk considerably, with no weird stuff going on.

Any ideas why ammo would act that way? It was factory new, bulk USA made, headstamp is JAG.

Lead bullets? To heavy a bullet weight like 220 grain?

180gr FMJ

I'd just avoid that ammo. You would not be the first person to experience keyholes shooting cheap bulk 10mm ammo. Jagemann brass is sometimes used for pretty good loads, and sometimes for crappy loads, that go bang, but throw bullets every which away.

Yes, definitely won't use that anymore. Just curious as to why this would happen. Same size/shape/weight bullet as the other load, not sure what would cause the bullets to tumble. I've heard of it happening, just not with me.

Actually, I've got an old Marlin lever 22mag that won't stabilize hotter loads. Seems the micro grooves are not aggressive enough to grab the bullet and apply twist if they are moving too fast. They would spray all over the place. With different loads it would hold 5/8" groups at 50 yds with ease.

Are you sure there's nothing wrong with the pistol; that's pretty horrendous accuracy for just 20 yards. Muzzle okay, recoil spring guide not broken or chipped anywhere, locking lug not broken, sights not loose, etc???

That's what I thought immediately is that I had some issue going on. I was packing up the gun and my buddy says "why don't you try this other ammo". It was the same weight (180 gr) fmj by a different manufacturer (S&B) . Proceeded to fire a 12 round group of about 4", which was obviously much more within reason than what is pictured. None of the flyers, key holing, etc. That's why this seems weird. I plan to try again with a couple more types of ammo to rule out any other issues.

The bullet may be undersized for your bore. You can pull a bullet and mic it, or just shoot different ammo and be done with it.

Another possibility, thanks!

Are you sure they are FMJ and not plated? I've experienced that before with plated bullets, especially in 10mm and the Glock bore. The plated stuff is generally too soft to grip Glock rifling at higher speed and pressure, where normal bullet jackets work fine.

Loose sights cause key holing?

This

I guess I'm not sure about that, but thanks for the info. Polygonal rifling issue, I guess? I sold the rest of that lot to a guy who will be shooting them in a 1911, so hope he has better results.

Sorta, more of a plated bullet issue. They usually don't work that well in any rifling type at high velocity/pressure, but issues show up a little sooner in the Glock bores. If you were to run the same bullets at low pressure in the 800-900 fps range, they might shoot just fine.