From the grave.....
That explains all of the Kimber recommendations.
From the grave.....
While I do agree a stronger recoil spring is definitely a good idea its not the issue that is always brought up concerning the Delta. Case support is or lack of is what always is. The Delta does not have a ramped barrel and most will tell you one is needed for the hot loads.
I took brass from Underwood & buffalo bore that I shot in my Delta to the NRA show and showed them to starline brass, double tap & Colts custom shop manager. I took the worst examples I had. Some did have slight bulging or as double tap called it mild " glock smiles". All of them in separate conversations said they were in no danger of a rupture. Double tap even stated that the glock 10mm was worse than the Delta and people never think twice about shooting the hot stuff in the glock. The only thing I was cautioned about was if there is a bulged case not to reload it.
Underwood has said new powder blends they use keep velocity up and pressure down.