My dad used 270TSX out of a 20” barreled 375 ruger last year…. They worked perfectly.
I could see their usefulness out of a 375RUM or 378wby…. But not sure they’d gain anything out of the h&h….
I think it was Craig Boddington who wrote about how he felt they actually robbed the 375H&H of some of its versatility due to being considerably slower than “standard” weight bullets.
