First Round Problem

[1750Shooter]

Took my new Grendel build (American Spirit side-charger w/Stoner barrel & bolt) to the range & using AA mags, it would jam the first round against the barrel extension. After I cleared it, it would feed fine. Any ideas why?

[LRRPF52]

What type of ammo, what type of malfunction?

If the meplat of a hollow point gets stuck riding up the feed ramps, it usually happens on the lip of the extension feed ramps that is overhanging the ramps in the upper.

This is why I personally hand-fit the AR15.

[1750Shooter]

Happens with both PPU 120 gr hp & Hornady A-Max. As I said tip of round jams against barrel extension fwd. of locking lugs.

[37L1]

Try changing magazine?

[jagonh]

is the magazine locking tight in the well?

[1750Shooter]

Yes to both.

[Bwild97]

Have you radiused the ejector pin? Sounds like the rim of the cartridge is hanging up on the ejector pin.

[1750Shooter]

Cartridge is not even engaging bolt face at time of jam. Strips from mag & angles up into bbl extension.

[Bwild97]

Post a pic of the malf. If you can please.

[1750Shooter]

Wish I could, sigh... Tail of round is just coming out of mag & nose is against barrel extension. I think I'm going to change out the spring on the chance that the bolt velocity is too slow.

[jagonh]

Is the buffer spring binding?

[1750Shooter]

Not that I can tell, but if it was why would this occur only on the first round?

[rabiddawg]

You aren't binding the mag by putting that last round in there are you? Iirc, I caused a malfunction with one of mine by loading one too many. Plus, there are many guys on here that report being able to use only 4 out of a 5 rounder or 9 in a 10 rounder ....

[jim_bob]

Sounds like the mag is holding on to the projectile too long. I usually fill my mags and let them sit for a few days before I use them. I have also ran into a few mags that I could not load to capacity, those end up being range mags.