While a firm grip on the bullet is needed, the back groove should be OK if you full length resize and give it at least a shallow crimp. I do not generally crimp for single shot rifles, but some times I get better consistancy if I do crimp. You will just have to try it to find out. With a short barreled gun or a repeater I alway crimp. I have some of those bullets and I seat them to the back groove for my Handi Rifles, but in the front for my revolvers and lever gun. I always full length resize straight walled cases. I would only partial size a case, but I can not get good enough consistancy to suit me. Good Luck and Good Shooting