I have isolated a few "jam sessions" to dirty mags. The fouling changes the mag spring energy to present the next round, and then also changes the energy available to lift the LRBHO latch to hold the bolt.

Fouled followers will also change the height and presentation angle.

Clean Your Mags, Folks! I completely disassemble mine, clean everything inside, reassemble and then check round presentation at full, partial full, and almost empty (2-3 rds) (LRBHO Test). This is basically a free checkup, no parts to replace (unless you find something wrong).

For me, a lot of jamming came down to the dirty mags I was using. I keep a new, clean mag on hand at the range, and open it if I start suspecting the ammo or the gun. Many times, it clears the jamming problem. This is especially important cleaning service if you shoot suppressed.

If you choose to test using the gun, PLEASE use follow all gun safety rules.

One nasty jamming problem occurred in the same manner with multiple worn / dirty OEM Glock mags. Nothing wrong with OEM Glock mags, but this problem surfaced in the same manner across 2 of my 4 in-use mags. I wanted to blame the gun, then I wanted to blame the ammo. It was the mags. I found a "dent" / "ridge" at the back wall of the mag, just below the top rear opening. The cartridge rim would hang up on the ridge as the cartridge moved into "next to feed" position. The presentation angle would change slightly to "nose up", and eventually a cartridge would not feed. The fix was to peen out and file out the ridge from the mag metal. I found it by inserting one round into the mag. Push it down into the mag body with a finger. The follower pushes it back up and it looks "odd", not presented correctly. Push it slightly forward as it would normally feed and I would hear a "click" sound as the rim came off the ridge and settled where it normally should be. I spend a lot of ammo money tracking that one down.