The 400 MOD harder SS Bartlein barrels are getting 75% - 100% longer life. Makes an overbore cartridge more livable as a hunting rig. Not blowing rounds out one after the other is always helpful.I definitely prefer the M5 Hawkins hinged floor plates on hunting rigs. The M5 just in case the stock or gun use is changed and a DBM becomes needed. I can’t offer much suggestion on cartridge but I too think a 0.277 caliber is becoming really interesting. The 27 Nosler sounds sexy. It would definitely be a hunting rig with a short barrel life. I have wondered before about a 300 whinny necked down. Would be on the heels of the Nosler in the 30 cal data stays true.