Anyone shooting swifts in the 450 Marlin. Mine is a repeater so I could shoot 500s? I guess?

Steyr Big-Bore for those that needed to know. The black one with no sights and a 1913 rail.

Congrat with your new gun.

I got a 458X2" American. I forwarded a question to Swift about the required impactvelocity for their A-Frame to guarantee expansion/proper functioning. And from the answer I got I definitely ruled out 500grs, and even the 450grs are iffy. I can't find the mail from them now, but somewhere between 1800-1900fps as far as I can remember.

I'm using Woodleigh 400grs PP now because of excellent feedingreliability. I was also looking at the 400grs A-Frame, but it isn't as pointed as the Woodleigh, and might've given me a feedingreliability issue.
And then you have the 350grs Barnes TSX.

350-400grs seems to be the best bulletweight for this cartridgesize of .458

400gr Swift A-frames work perfect at 2400 from my .450 Ackley.