No roll crimp needed in a single shot. No problem igniting "slow handgun powders" in a single shot without a roll crimp. In fact, I've found a roll crimp hampered accuracy over just tapering the case mouth flush with the bullet. No problem adding Lil Gun, as long as there is room in the case. Lil Gun is not running anywhere near max pressure with a full case under a 158. I've been there and done that, and done it, and done it, and done it. No idea whether it is kosher, just that it works, and I have never seen anything unsafe in the practice.
My brother has a Marlin with a 20" barrel, and his standard load for 158's is 19 of Lil Gun, for about 1900 fps. He uses 16.5-17 under 180's. That's impressive, but what can be done in a single shot, depending upon the leade, is something else, because the max COL is generally much longer. The chamber's dimensions, just like in any other rifle, determine what you can do with it.
Last edited by HuntnShoot; 09/14/19.
