Mini 14 - HELP

[USMC3041]

I have a friend who has asked me to help troubleshoot his Mini. He purchased it new this year.
Problem - Failure to Fire I have given him some suggestions (all over the phone, have not seen the rifle or actual shell casings). Rifle works 100% with factory ammo. Works about 50% with reloads. Had him change primers to either Winchester or Federal. (he was using CCI). All of his reloads will work 100% in an AR after failure in the Mini.
I have several years of reloading under my belt, but not an expert. What if anything should I be looking for when I actually get to see the firearm, his reloads, failures and reloading technique. Will be taking with me a mic, and some of my proven reloads for an AR.
You have as much info as I do at this point. Thanks.

 

[Regionnus Rattis]

when loading for a semi auto especially ones with a free float firing pin you literally can never seat a primer too deep. what brand of dies are you using? the older lee .223 dies and some batches of rcbs dies would push the shoulders back too far for semi autos. this is what seems like is happening to you. back your sizer die out 1 and a 1/4 turns and gradually turn it back in an 1/8th turn at a time at each 1/8th turn test the case in the rifles chamber till the bolt closes completely and easily on the case then turn the die in just a hair to another 1/8 turn and your die will now be set to the rifles chamber. hope this helps

 

[USMC3041]

Thanks for your reply, He and I have not been able to get together on this project. I passed your information along, he was headed in the right directiion in fixing this. Your information will go a long way in correcting the problem. I sir, even with 30 years reloading experience have learned something from you. Thanks again. Just goes to prove you can teach an old dog new tricks.

 

[451_Detonics]

I would agree the case is setting too deep in the chamber. A simple measuring with a good caliper should show if the sizing die is setting back the shoulder. On brass fired in the gun you might be able to get away with just neck sizing but not if it will be used in several different rifles.