I have a NEF, SB2, rifle with a problem. The gun originally came as a .223. I sent it back to the factory and had a .243 barrel fitted.
All .223 rounds chamber and fire whether factory ammunition or reloads.
The .243, on the other hand, fires factory ammunition WITHOUT A HITCH, but balks with reloads. I've tried different primers with no success.
I have several hundred new, Remington cases, and they will ignite about one out of five cartridges. I tried them unsized, FL sized, and neck sized, with the same results.
I've FL sized fired cases (spare cases fired in this gun) and they will not ignite either. Also, once a case is fired, the case will rechamber without a problem, but 100% of the time, it will not eject.
I sent the dies, and a couple of fired cases back to Lee, and in an e-mail, they said the dies resized the cases back to specs.
I would appreciate any ideas you may have concerning this problem.

hi bej -

sounds to me like you may have a couple of problems working against you.

1st - clean the ejector and check the chamber for burrs, etc. clean up any burrs or machine tool marks that may be in the barrel. i would send the barrel and receiver back to NEF if you have a lot of tooling marks.

2nd - the non-fires. how are you priming your cases ?

SG

Thanks for the reply. Previous to my original post, I had taken the gun to a 'smith who tore it down to check the firing pin, ejector, etc. He said there were some brass bits in the firing pin hole, the ejector box was dirty, but otherwise, all was fine. The chamber has been polished and there are no tooling marks inside the chamber nor are there scratches on the brass fired in the gun.
I usually prime in the press as a separate operation. I do have a hand primer tool, though.

Since the .223 and the .243 have a different rim size, it's possible that the extractor is the problem; either the old .223 extractor was left in, or the new one was not fitted correctly. Just a wild guess. The extractors may be the same in the NE for all I know. They are definately different in the Ruger single shots.

The firing problem COULD be excessive headspace and the pin is bouncing the loaded cartridge forward, absorbing part of the blow. How do the primers look after failing to fire? I have an old 30-30 that does that; I corrected it by adjusting my sizer to headspace on the shoulder like a rimless case.

Good luck!