Howdy
Check out Marvell precision, they make THE best 22 conversion and they are VERY accurate. I have one of these and can sya that it is VERY high quality. Mine is a base unit but i have friends that have the Target models and they are about as nice as you can get. Also you might want to check with Storm Lake Machine and see if they make a .400 cor-bon barrel for your gun. The 400 might give you what you are looking for, and all you mags should be good for it also.
Have fun and shoot safe!
Conley Janssen
USMC 87-93