Pierce Engineering built one for me in 2015:
http://www.pierceengineeringltd.com/Pierce action, Krieger barrel, Mickey stock. My rifle is very accurate and I enjoy it a great deal. However, I'm not sure I would build it with the Raptor again or use the Bushmaster.
Remember, when you look at loading data and ballistics for the Bushmaster, it is almost always loaded to a max pressure of around 40,000 psi for use in an AR. There are a lot of guys loading the Bushmaster towards 60,000 psi for use in bolt guns and are getting the same velocities as the Raptor. Don't buy into the velocity hype for either cartridge. There are guys claiming big numbers with hotrod loads that I am sure are beyond 65,000 psi.
Another point to consider for either cartridge is the powder you are using. The highest velocities for both are almost always recorded with Lil'gun. This powder has a reputation for burning out throats when used at high pressure. Google "Freedom Arms+Lil'gun" and you can read about it. Most Bushmaster shooters dismiss this, but they are typically shooting it in cheap barrels. I am not willing to gamble a Krieger for a little more velocity. In my view there is not a really good powder for this application if you hunt in a cold climate. H-110, Accurate #9, and IMR 4227 produce high velocities but can be problematic in the cold. H-4227 would work well but it is history. Accurate 5744 is very accurate and not sensitive to the cold, but produces low velocities. I settled on Ramshot Enforcer pushing a 250 gr SST just under 2400 fps. Very accurate but I'm sure I'm losing some velocity when the temps head to 20* or lower. I need to chrono in the cold!
Send me a PM if I can be of assistance.
405wcf