metal AR mags in high heat

[SubVet10]

I did a tactical rifle shoot in Southern Oklahoma. It was a single rifle event, meaning the rifle you checked in is what you used the whole day - no changing optics, grips, etc. The courses ranged from a CQB run at 7 yards, to long range targets (90 second stages). The good news is I had never shot past 100 yards before, but I was ringing 12x12" steel at 300 and barely missing at 400 (thanks to the time crunch).
Anyhow, the overall scores with poop because of constant magazine malfunctions. I read the Marines (tragically) had similar issues in Iraq and it seems the metal mags get can get cranky at temperatures above 90 degrees. They wouldn't seat or feed correctly into an empty chamber. For me, I'll keep the metal mags for indoors and polymer for the blast furnace temps of the South. Just something to ponder about.

 

[DLJeffs]

Springs weakening in the heat? I think I maybe had one jam on my M16 my entire 4 years on active duty. I didn't particularly like the rifle but it seemed to function OK and take lots of abuse. I shoot left handed so hated the hot brass always hitting me in the face.

 

[burlyfigured]

Was it just one kind of ammunition used? Length of cartridge can gum up anything.

 

[SubVet10]

Springs weakening in the heat? I think I maybe had one jam on my M16 my entire 4 years on active duty. I didn't particularly like the rifle but it seemed to function OK and take lots of abuse. I shoot left handed so hated the hot brass always hitting me in the face.

DL, that would be my guess. I admit I didn't have a lot of faith in it during my early days on active, (though I despise the M9 still) from all the horror stories, but it's the first issue I ever had. *edit - it could also be expansion of the mag itself. They didn't seat correctly, either. A possible drawback to the tight tolerances?

Was it just one kind of ammunition used? Length of cartridge can gum up anything.

That's the thing, it wasn't just my SIG lower. It was the whole gamut. I had Winchester white box 55gr, others had subsonic, and everything in between. At least 3 or 4 of the group of ten I was in.

 

[burlyfigured]

Could be the heat expanding the top of the clips also. That sounds like a great weekend and some great shooting, despite the setbacks.

 

[DLJeffs]

Yeah, if the mags weren't seating correctly it sure sounds like the whole casing was expanding.

 

[Eric Rorabaugh]

IMO it was the heat causing the lip on the top of the mag opening to swell closed a little. Enough to not feed. We changed from metal mags in our Colt M4's to PMAGS.

 

[Eric Rorabaugh]

And speaking of range, I have range tomorrow. Us instructors gotta be there at 11 (through the hottest part of the day) so we can get everything ready for them. Instructors may even get to shoot a Lil 🫰

 

[SubVet10]

And speaking of range, I have range tomorrow. Us instructors gotta be there at 11 (through the hottest part of the day) so we can get everything ready for them. Instructors may even get to shoot a Lil 🫰

Hope the shoot went well for you today, Eric. Burning the extra ammo was always a nice perk of being a Line Coach. Especially drawing smiley faces at 25 yards

 

[Eric Rorabaugh]

It was good just hot. You Texans need to come get these ridiculous temps. This mountain boy don't like it hot.