I don't have any 338 gain twist barrels, I bought one from a guy in Las Vegas but sold it back to him. It was a 13-5.2, I believe this is probably the barrel Lowlight is using to test the solids being discussed on Snipershide. Bartlien was the only source for these barrels and they are not producing any more of them. I have two of them but both are 375s. Lilja can do a 7 twist in 338 and I believe the constant twists will work as well as the gain twists.