Out of curiosity, I'm trying to figure out what are the potential barrel swapping mechanics are for my H&R 370, which is a FN Mauser "Supreme" Commercial action from the 60s/70s.

It is in 22-250, so, 250-3000 savage would most likely be a simple and easy barrel swap. *but also kind of pointless*. So, lets say for example I wanted to switch the barrel to something in the 28-30 caliber range? Such as a 308? Or maybe even get a new bolt and barrel for 223/5.56?

It’s as easy as rebarreling any other Mauser. Pull the barrel. Indicate new barrel in lathe. Cut threads to fit action. Chamber and set headspace. Torque barrel on and test fire. Check feeding. Finish barrel to suit your tastes.

223 conversion would be a giant money pit needing a bunch of parts fabricated by a competent gunsmith. Stick with the original head diameter for the best results with the least amount of work.

Ok.

What other calibers can I go for easily with for 22-250'd action?


Also, I am not a gunsmith, have no access to lathes (or other tools.)

Without a lathe, and sans skills, none.

With both, anything with a .470" boltface You'll probably want to remove the spacer from the magazine for longer cartridges.

I'd go to a Gunsmith. Is there a nice list of .470 rim cartridges i can go look at?

A couple of lists with rim diameter, but not sorted.

https://mcgowenbarrel.com/ammo-dimensions/

https://www.cartridge-corner.com/riflelist3.htm

Bruce

that is quite helpful, thank you.

it looks like all of these are .473 (except for .47 of the first two 308s)

308 Win (7.62 Nato)
308 x 1.5"
285 OKH
280 British
280 Rem.
284 Win.
284 Win. Magnum
284 Hawk
30 Kurtz
30 IMHSA
30-28 Gerlich Experimental
300 Savage
300 Hawk
30-06 Improved
30-06 Springfield
3200 Hawk
333 OKH
338 IHMSA
338 Hawk
338-06 A Square
(30-06)
35 Whelan
350 Howell
358 Win.
(30-06)
375 Whelan
375 Hawk/Scovill

And of that list, only 308 is anything I'd have actual interest in shooting... I was hoping for some more lower 20-24 caliber cartridges, or even a 17 speedy boy... Hell, most of these I've never even heard of, and I'm guessing most of them are also long actions. The 308x1.5 looks like a weird one.

anyway, thanks again for the links, very helpful.

Also 220 swift, 243, 22br, 225 win, 25-06 and a few others.

Looking for a .24? 6mm Rem is a shoo in.

6.5x47 Lapua, 6mm creedmoor, 257 Roberts, there are many times more than what's on that list

IIRC the H&R had a very thin barrel. Matching barrel contour might be more difficult than deciding on a chambering. If you are changing stocks - problem solved.
I have a new Shilen 22-250 barrel, 14 twist, that I would part with. It is an SSK 35 contour (.55" @ muzzle)

It (the 370) has a straight heavy barrel.

https://i.imgur.com/usP0p5k.jpeg

https://i.imgur.com/kO4bzw6.jpeg

The 300, 301, 317, 340, rifles had lighter/standard tapers (sporter and varmints), 301 barrel pictured here (with a 360 to the left) https://i.imgur.com/YOKma99.jpg

22 or 6mm Creed?
Pretty obvious I'd think.

6mm or 6.5 x 284?


Send it to ER Shaw.
If you are happy with good accuracy and the lack of prestige.
It will come back complete, for about the price of a top level barrel.