Problem with carbine loads

[rider]

Here is what I meant by "failure to feed." The case fires, but not with enough force to cycle the action. I have to cycle the operating slide by hand to extract and eject the case and feed the next round. This happens about 10% of the time. I hope this clears up this point.

What you're describing here is a failure to extract or FTE. Feeding is the next cycle, then chambering and firing - or something like that.

[Litt'le Lee]

are you using them ??

[browningautorifle]

I've loaded a lot of carbine ammo and I've found that 2400 Herco works best in my carbines. I try to duplicate military loads as much as possible and use gas check bullets when using cast bullets. If it won't cycle the action, it simply doesn't like that load.

[Sunray]

Like rider says, it's a failure to extract. Highly unlikely to be caused by the powder charge. 15.0 grains of WW296 is a max load(2106 FPS). Hot for a carbine. Far hotter than factory.
I'm wondering if the load is too hot for the gas system to work properly. Shouldn't be, but give it a really good bath and try some IMR4227. 13.0 to 15.0(compressed). IMR4227 has worked extremely well out of my carbine with 110 hrain HP's for 30 some years. Runs around 1900 fps. OAL of 1.680".
"...requires Mag primer..." Cartridge goes bang. It's not the primer. You don't need magnum primers, like CCI "milspec" primers, for any carbine powder either.
"...then trim each case to 1.280"..." Trim before you expand 'em. The trim-to length is 1.286" as well. At 1.280" your headspace is off.

[Calif-Steve]

This load is the factory specified load. I use it all of the time. Is this carbine clean? Have you tried 14.5 grains instead of 15 grains? Use a good magazine and clean the carbine. Use white grease to lube it and good luck.

[Larry Gibson]

I've looked up the pressure curves for that loadout, and while it does appear to be in spec/37,000psi, try reducing 0.3-0.5 grain on the off chance you have high-pressure/sticking cases that hinder extraction,

BEFORE.....doing anything else

Concur with MEHavey's advise, 15 gr 296 with a 110 bullet is possibly an over max load for your M1. The residual pressure in the chamber still has the case gripping the chamber when extraction begins. This is no doubt what is causing the malfunctions. Suggest dropping at least to 14.5 gr 296.

Larry Gibson