Problem with carbine loads

[Sid]

My M1 carbine functions perfectly with factory ammo. I have shot LC, Aquila, and Prvi Partizan without any problems at all and they produce acceptable groups with the sights set for 100 yards. However, with my hand loads I have to set the sights at 200 yards to get on the bulls eye and I also have frequent failures to feed. Here is how I prepare the reloads. I clean the cases in a tumbler, then full length resize them, expand them, then trim each case to 1.280." I use a charge of 15.0 grains of WW296 and check the charge on a scale at regular intervals. None of the cases have been fired more than 3 times. What am I doing wrong? Any help will be much appreciated.

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[kcw]

My M1 carbine functions perfectly with factory ammo. I have shot LC, Aquila, and Prvi Partizan without any problems at all and they produce acceptable groups with the sights set for 100 yards. However, with my hand loads I have to set the sights at 200 yards to get on the bulls eye and I also have frequent failures to feed. Here is how I prepare the reloads. I clean the cases in a tumbler, then full length resize them, expand them, then trim each case to 1.280." I use a charge of 15.0 grains of WW296 and check the charge on a scale at regular intervals. None of the cases have been fired more than 3 times. What am I doing wrong? Any help will be much appreciated.

If you're shooting at the "club" someone may have a chronograph in their car that they'll set up for you to take a few shots over. The info from that should at least give you a starting point as to your problem.

[joem]

I trim my cases before expanding them. Have you chrono'd your load. I use AA#9 and load to 1980 FPS. Also check the gas piston nut to be sure it's tight.

[Sid]

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.

[MK111]

Where do the shots that fail to work the action hit on the target? High or low? You may have less powder for some reason on those cases. Make sure your powder is the same charge for load to load.

[MEHavey]

What powder/weight-bullet combination are you loading, Sid?

[Sid]

I am using 15.0 grains of WW296 with 110 grain FMJ bullet

[MEHavey]

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

[Alfred]

How much have you had to trim, and were any cases far longer than the rest after first firing?

A friend who owned a surplus store had one carbine that was brought back several times. he asked me to figure out why it was jamming.

This carbine would lock up tight, so tight you'd have to kick it open.

Jams were aproximately once every six shots.

I checked the fired cases an one out of six were as much as .006 longer than the rest. I checked the unfired ammo and found one in six longer than the rest.

On later production carbines a tiny protrubence was left on the right hand locking surfaces of bolt and receiver, to provide a resistence to flying open from inertia if dropped hard on the butt. If a case is too long or stretches farther than it should the bolt is hung up on that little knuckle.
The raised spot in the center of the RH locking surface on this carbine was larger than it was meant to be and easily visible, so I stoned it a bit. There were no more jams.

Its been many years since I made this fix so I don't remember what the matching spot on the bolt lug looked like, whether it was a raised spot or an indentation. Ordinarily these are nearly invisible.
I'd heard of this sort of jam many years before so it wasn't hard to figure out.

[jjroth]

detailed the gas piston?
Factory maybe moving a sticky GP, when the lower reloads might not??
Have you run a .44 brush in to chamber?? That miht help.