In case anyone is interested so they can use an exterior ballistic chart, the 180 grain bullet that S & B loads in their factory ball ammunition is a boat tail with a BC in the 0.496 to 0.50 range, depending upon testing method used. From my hollow pointing experiments to make a cheap hunting round, it appears to be a solid lead core bullet all the way to the tip. If you try to adjust the COL of this load for your rifle, you should probably stop when you expose the bottom edge of the crimp groove. More than this and there is not much bullet left for the case neck to grab. Your SMLE magazine length will be a limiting factor too. The S&B product number is SB33130