Al in Mi wrote:the 50XS is on a Oly WSSM upper which has the larger diameter nut and a larger diameter barrel extension, an Oly exclusive. I don't think there is enough meat in the threaded end of a standard AR15 upper to make it work. I have one of Detechs .243 wssm uppers (which is a Oly), I'll see what I can measure up for differences without pulling it down. Things a laser and I don't want to mess with it too much.
I've looked at this sideways, straight on, backwards, upside down for a couple of years now, and the only option I seen is pulling down a Oly and rebarreling, or the AR10 route which I'm headed for.
If I were entertaining a large bore AR build all over again, it would definitely be based upon an AR10 platform. More flexibility than the Olynpic/Dtech rigs, which I have one of. Too much restriction on bullet and charge weight choices due to the 2.26 inch magazine COL limit.
My 300 WSSM (OSSM) is quite a handful. Shooting it before or after the 450b, my perception has been that it is a more violent reaction than my 450 Bushmaster feels like and the math supports that sensation. Tossing a 150gr bullet at 2950, which is 100 fps below HSM's claimed velocity for their factory loads (that I have not been able to duplicate and have a half-way accurate result with my loads), yields a calculated muzzle energy of 2900 ft/lbs versus the Hornady 450b load that calculates to 2687 ft/lbs at the muzzle. That's not the same as TKO factor, where the 450b eclipses the 300 WSSM though. Of course the flip of that coin is the 300 doesn't drop like a rock out past 200 yds and yes, I consider a 32 inch drop at 250 yards and 50 inches at 300 yards to be like a rock. Different calibers with different missions, that's all.
Hoot