Thanks for your service airborne! I had the same probs with my factory twist remmy, ended up with the most accurate and most lethal round thru mine using Hornady 52gr Bthp match #2249 with 38.5g of H-380. The Sierra blitz was accurate but blew up too much in 50's and 55's wont stabilize. Try slowing your poly tips down to reduce blow up, I did but lost accuracy so ended up back at the 52gr Hornady. Hope this helps, good luck! I have tried almost every bullet/powder/length combo thru that gun and have a pile of "test subjects" (coyotes and p-dogs) to help me decide.