Yes, I should have mentioned that Thompson Center made the White Mountain Carbine - WMC.
The WMC was first offered in 50 Caliber (approximately 1990 ) with a 1:20 twist then about 2 years later TC started manufacturing them with a 1:38 twist.
The WMC was also offered in 45 & 54 Caliber but both of them were only offered with a 1:48 twist.
While we're on the subject of 50 calibers with 1:20 twist, TC also made the Tree Hawk that was like a carbine version of their New Englander . The Tree Hawk was offered with a synthetic stock and the whole gun (Lock, Stock and Barrel) was camouflaged.
So if you want to try these 395 SPHP bullets or some much longer bullets here a few more options.