Guys, I'm experiencing jamming - fired case and next round trying to occupy the same space. I hand load using IMR 4064 behind a Hornady 150 FMJ in LC brass. Head space is checked (Wilson) on each case with cases trimmed to 2.005". It rests between min and max in the Wilson. Today I was fine tuning to find the best accuracy. Last time is was 42.5 grains and this time it was 42.7 grains. Optic is Eotech 552 XR308. OAL is 2.780" as recommended by Hornady. I think I had less problems at 2.735" but could be coincidental. I'm using a P-Mag 10 round mag for the bench shooting. Mag is free and clear from bench or bag.

This happens almost once every 5 rounds (I load 5 of the same weight powder in my trials). Today it was 42.1 to 42.7 grains with each charge weighed on a RCBS beam balance scale. Ejection pattern is strange. It sends them anywhere between 4 o'clock and 1 o'clock.

I'm at a loss. Today I pulled the bolt carrier out (lubed with Slip2000 by the way) and rotated the cam pin 180 degrees just for the heck of it. I noticed it's got a pretty good wear pattern in one spot already though. The next 10 rounds ran flawless. Strange.

So, anybody experience this or have a guess why 2 rounds are trying to occupy the same space? Thanks.

So as clarification you are having failure to extract issues? The fired round is still in the chamber and a new round is attempting to chamber?

First place I would be looking over is both the extractor and and ejectors on the bolt.

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.308 chambered AR's are known for FTE's if the chamber is allowed to get dirty.

Blue - yes, that is it exactly. I will look at them tonight. Thanks! ***UPDATE*** Both look good to me after removal. The ejector seems like there's a heckuva lot of tension though.

Michigan - started clean as a whistle. While I agree with you - it just wasn't the case here. Thanks!

Failure to EJECT. This will be caused by short stroking, weak ejector or both. Short stroking could be an ammo problem. Ammo isn't developing enough power to operate the rifle

Ejector seems fine. I'm going to look at some loads on the web and see what's what. Winchester says their 7.62 mm 147 fmj that I sighted in with rates 2,800 fps. Mine are ~ 2,500. Thanks!

Update - loaded 20 rounds this morning with shorter OAL (2.735"). No FTE! Best ejection pattern came from the hottest load (2,721 ave. FPS). Seems to approach 7.62x51 MM data as well. Problem solved I think.

Webfarmer,

Did the OAL adjustment truly solve your FTE issue? Please keep us informed.

LlindeX, I'll report here next time I get a chance to shoot. 50 rounds are ready but turkey season starts Monday Hopefully a long beard will be taking a dirt nap soon and my M&P 10 shooting can continue (I hunt and shoot where I live). Good luck!

I have learned that mine loves Frog Lube and does not like to run dry.

Well lubed, she runs flawlessly.

Update for LlindeX - was finally able to shoot another 50 rounds through the M&P 10 today. Zero FTE's again with my reduced OAL reloads! Must have been the root cause (strange). Enjoyed zeroing in at the 100 yard range and then switched to the gong - what a blast!

I ran into the same issue with some of my reloads. I also believe it was due to OCL. I was loading 168 bullets with imr4064 at 44grs. I think it was catching the pmag. It was only happening with one of my 50rnd lots when the mag was completely loaded. I when through 250rnds that day and had 3 jams with that lot. Each time I pulled the bolt out and did a barrel inspection. Just to make sure I didn't have a squib round stuck in the barrel. I always do that for any round that doesn't eject.

PS. I went to 44.5grns with 168 bullets with no pressure signs. This was using LC Brass.

Huh - now that is interesting. My load for the 150 FMJBT bullet is 44.0 grains IMR 4064 in LC cases. Rifle likes it but man those cases are hot to the touch after ejection. How's your M&P 10 accuracy with your 44.5 load?

I didn't get to really test the accuracy. The range by the cabin didn't have any of the target post left and I left my 10rnd mag at home. I don't think I would go anything over 44.5 with the LC brass. Next time I'm going to also remember my chrono. I'll let you know what I find out.

awsome information-thanks to all that shared.