Just for information; I wanted to build a couple of 450 Bushmasters. I have done them on 98 Mausers before; no problems. As I have some 91 Actions on hand, I thought that would be a perfect platform; I knew the Bushmaster case was fat, but I thought it would fit the magazine.
It won't. No way. Scrap that COA and use a 98.
Have to put a 35 Remington on the 91s; they work well with that.
I have no use for a 7.65 nor do I have any good barrels; otherwise, that works too.

I did a 91 in 45 auto.
It was fun. I tried lots of various loads, shooting out to 5-600 yds across new harrowed ground to watch the dust spurts.
I got tired of it in time and someone else got a new toy.

Thought about a pistol round but don't want one. We can use straight walls here for deer now.
Maybe I'll made a 40 cal straight rimless.

Don't remember all the details, but some time ago, I ran into a guy who was working on a rimless straight wall using 8x57 brass trimmed back just below the shoulder resulting in an inside neck diameter in the neighborhood of .430" (+/-). His plan was to use 44 Mag handgun bullets. IIRC, he was gonna call it a 444 Short Rimless.

Yes, that is an easy cat; and don't even need special sizing dies. I have done prototypes of that. 30-06 is better; depending if your state has a case length limit.
The reason I wanted a 450 Bush is for re sale potential; it is impossible to sell a wildcat to hunters.

Tom: used a Rhineland arms barrel on a mauser 95 in 450 bushmaster. Savage style lock ring on the barrel and it worked out just fine.. Cheers luke

Sure; I just thought I would put one on a 91; they are so smooth, but it won't work. I have plenty of actions of all types.