From my perspective there are two issues: the first is the velocity loss of approximately 50 fps for every inch of barrel reduction and the second is decreased sight radius. If you are shooting with a scope then decreases sight radius will not an issue for you, however the velocity reduction will definately somewhat degrade long range performance.
My 168gr loads do approximately 2700fps out of a 22 inch barrel, and only 2550 out of my 18.5 inch barreled guns. Their relative long range accuracy is, IMHO, primarily dependant on where it is along their trajectory they go transsonic (approximately 1250fps, depending on environmental conditions). With an initial velocity of 2700 fps, again depending on environmental conditions, this is around 925 yards. With an initial velocity of 2550, this is approximately 850 yards.
I regularly practice with my 18.5 inch barreled guns out to about 600 yards and find it frustrating beyond that. This is more a function of optics though as on all my scout guns I run scout style optics....low magnification mounted way forward.
Anyway...ask yourself what it is you want from your M305. If you are building a DMR type gun then you'll want the original length barrel. If you are looking for something a little more handy (and lighter (less mass) optics are just as, if not more important than the shorter barrel from this perspective) a la "scout" concept, then go for the barrel buck job. I'd submit that very few people practice out to 1000 yards, myself included. About the only time I play at these kinds of ranges is with my bolt guns. I am working on a .416 project that might change this, however that would be a story for another thread and another time.
Good luck!
Brobee
