A few Glock owners I know replaced the barrels. They were reloaders.
https://hodgdonpowderco.com/wp-content/uploads/2023/04/website-warnings-rifle-pistol.pdf
I enjoy my 40's, CZ and Beretta.
Nothing wrong with a 40 S&W. I own 2, CZ75B and a Beretta Cougar both are +P. Both are fantastic. I also own 2 9mm's. If any had to go it would be the 9's.
There are so many great powders for 55 gr bullets. It all depends on what 55 gr bullet your rifle likes, not just the powder. Varget works good for me but others at my range swear by a dozen different powders. No simple answers to your question. The Lyman book marks their most accurate loads as...
Remington 700 CLASSIC 7MM-08 , beautiful, beautiful rifle, shot horrible. bedded the action, free floated the barrel, never found a load it liked. never below a 2" group. was happy to end the suffering and sell it.