6.5 Grendel?

The big problem are you are extremely limited to short bullets because it has a very short throat. Remember it was designed to shoot aroud a 120 some grain jacketed bullet. I did take some Loverin style bullets, before I got that Saeco bullet, and sized down the nose of them far enought that it would all fit throats.  I only did that for awhile and I was able to get 3/4 inch group at 50 yards with them. BTW I exclusively used H4198.  There was also a big difference in the loads and velocity using the Lapua cases (small rifle primers) and sized down whatever brand of 7.62x39 brass (large rifle primers).  Hope that helps some. The Grendel is plauged some as a cast bullet cartridge because, as stated, it was designed as a jacketed round, that is by the throat design.