[,quote name=survivalshop" post="142357" timestamp="1428065863]
LC Once fired Machine-gun brass is all I use any more & I don't have a problem with them . I use the same Sizer Die the OP is using. I don't use my SB RCBS die much any more ( very old ), unless I have a case that was sized before with a SB sizer die, because of case length after sizing , they are always shorter than " Trim to Length" spec , when sized with a FL Sizer Die.
His main problem was a problem being able to properly set the Sizing Die ( case Head spacing, shoulder set back ) OP said he used different types of brass. The rifle Head Spaced OK , so the chamber is to spec's & shouldn't matter what brass is used as long as it is loaded correctly , to spec's .
As was said, the tight extraction should go away with fired round count increase .