Love that bullet in my 243. Also had to get H 414 when powder was hard to get and it really worked well. But powder has nothing to do with OLL. You can load the round to be just off the lands, I do, but when loaded that way the round may not fit in the magazine. The 243's I hve, two, both let me load bullet's out to the land's and still stay just off the lands. Rem 700 ADL and a Mossberg Patriot. Probbly work alright in your rifle too. 243 is 308 case. Had a 6mm years ago and the case was just to long and couldn't do it. If I remember right it was/is on the 7x57 case length. Doesn't work that well in a short action.