I have been thinking about buying a old custom mauser rifle built by Mashburn arms long time ago that is marked on the barrel 375Magnum.Lady Owner knows nothing about it & wants to sale.To be safe i know i have to find out what it is chambered,Instead of doing a chamber cast,if 375H&H brass will chamber,can i just fire form the 375H&H brass without a bullet to get the chamber diminsions to see exactly which 375 it really is or should i chamber cast it anyway?Will the brass tell me about the headspace?I read the other day where there is a wildcat called the 375mashburn! Also it could have been a 375weatherby? I would say the rifle was built in the 1950s-early 1960s..Must be built right as it looks to have been fired alot thru the years...The Barrel and action look really nicely built,If the chamber is a wildcat that has to have fireformed brass,what could i bore it out to and keep the barrel thats on it now and use factory brass/ammo? 375 Remington ultra mag.? Also the action has the side mount scope and has been drilled with 4 holes,Has this weakened the action strength alot? I really dont look to much at rifles with sidemounts but this one is a neat old custom and hopefully salvageable...I think the action is a FN..It looks like a browning FN action bolt handle the way it sweeps back,I will try to post pics if i get it,What measurement can i take to see if its a true magnum action?Measure the bolt?Thanks for any help in advance!

i would order some cerrosafe from brownells, and cast it.. but, if the price was right, I wouldn't actually "care" what caliber, and would take the action on home.


drilling the sides? unless there's 5/16 holes all along the side, and it SHOWED, the side mount won't hurt a thing.

jeffe

If it is a wildcat 375 it could be:

375 Barnes Supreme
375 Express
375 Durham Mag
375 Whelen
375 Whelen Improved
375 ICL Kodiak
375 Mashburn Mag
375 H&H Ackley

And others do exist.

Being done by Mashburn, it could very well be the Mashburn Mag. Do a chamber cast and eliminate the guess work.

WoW,I didnt know there were so many 375 wildcats,I will for sure have the chamber cast. How to check the headspace & check for setback?I will have a gunsmith go over it real good,The pad is old and rotted,What kind of pad do i need to get that has the traditional solid thick red english express rifle look & where can i buy it?I saw one in the gun supply catalogs but it looked awful thin....Thanks big time for all the help!

It should be pretty simple to look into the chamber and see if it is cut for a standard belted case. If that's the case and a 375 H&H case chambers, it's unlikely that test firing a round to determine the chamber dimensions will cause a problem. If you choose to go this route, I would suggest a using a lead bullet and a load generating moderate pressures just to be safe.

If it’s a wildcat or not might try asking the person selling it if there is ammunition and or dies for the gun? This might answer all you questions.

Many years ago I bought a 375 H&H and as I was walking out the door the owner ask if I wanted the ammo, about fifteen boxes of new factory ammo. I always ask now.

Thanks for the help.We are Haggling over the price some now,she had it priced clean off the rector scale,,,The old pad is gone,,I figure if I gotta have a pad installed i might as well have the chamber cast and can allways go with a different caliber later on if its a really weird one now.I hope its a 375H&H.First thing i asked was about ammo type,dies,caliber,History,etc. no one knows.....All They said was they killed the last elephant in america with it and dont need it anymore...