JES rebores/rechambers the 338 Federal. Shortly after the 338 Fed came out, I talked to Mr. O about having a Savage 99 in 300 rebored/rechambered to 338 Fed, but he told me that (at that time) he had done a couple of 338 Feds on the Savage 99 and the owners were seeing high pressure signs with factory ammo. Apprised of the risk involved, I opted not to have the work done and I think that Mr. O's warning, knowing that he was likely turning away work, speaks well of him.
