Working on load for my nephews 50 BMG any help would be appreciated..... Have new IMI brass,neck-turned,flash-holes prepped,and primer pockets. Load 220gr. H50BMG with 750gr. A-Max. Load showed press on Head stamp. Gun is a Barrett Mod. 99/ scope nightforce 12-42X56. Max load is 233gr. of H5BMG. Same load in military brass shows no pressure signs.... Thoughts ... New brass is softer and way under sized .... that I should go with lighter loads to form brass. I have reloaded for several wildcats but nothing this large......

220grs of H50BMG and a 750 Amax is a pretty light load for pressure signs. I've used up to 240grs in my bolt guns with PMC brass. Some IMI brass has been reported to have its shoulders set too far back and some folks have ignition problems with it. Are you getting sticky bolt lift? Measure the base to shoulder length on new cases and on fired ones. I suspect your cases are streching big time on the first firing and causing this problem. Do not full length size fired brass, just neck size it and see if the problem persists.-Rob

Brass is undersized... No sticky bolt lift. But leaving extracter marks on head stamp.