Help ID Rifle

[Sam]

Cleaning out my dad’s safes I found a rifle he acquired in the late 70s. We went out to the desert and shot it a few times. Has not been out of the safe since. I think it is a Sporterized Mauser 8mm. The only markings on the barrel are: 7.91 above the action, BO 481 or BO 181, and a V towards the front of the barrel. I found some 8x57 ammo, so I imagine this is what we shot. But, seeing how the diameter of the barrel is 7.91, not sure how safe the 8mm ammo is.  This was over 40 years ago, so my memory is not totally clear. I remember the first time we shot it, we put the butt against and old tire and stood as far back as possible, not knowing exactly how it would shoot. Here are some photos. Anyone familiar with this rifle? 

I also found Ceskoslovenska Zbronovka AS BRNO. Forgot he had either of these rifles. 

[Crazymonkey]

Very  nicely  done  Mauser. 

[PRDATR]

I believe that is 7.9 with the letter i for "Infantry".

 

What is the headstamp on the ammo?

[Sam]

14 hours ago, Crazymonkey said:

Very  nicely  done  Mauser. 

Thanks. Looking forward to shooting it again.

[Sam]

12 hours ago, PRDATR said:

I believe that is 7.9 with the letter i for "Infantry".

 

What is the headstamp on the ammo?

I'll dig out the boxes and let you know.

[Phil Carr]

The best and safest way to determine what cartridge it takes is to do a chamber cast. I also always slug the barrel. Not hard to do and actually kind of neat to learn to do this. 
It very well may be 8x57. I copied this for information. This better details the differences. 
i recently camber cast and slugged the barrel of a friends rifle, a Combination German rifle.
His rifle was actually another cartridge of 8x57. I was determined to be a 8x57 JR . A rimmed cartridge.
 

 8x57JS, the "J-bore", was the original chambering for the Mauser. It had a bullet diameter of .318 inches and was a round nose deisgn. The 8x57IS, referred to as the "S-bore" was the later chambering with a new spitzer bullet with a diameter of .323 inches. Early rifles chambered for the J-bore and subsequently modified to fire the larger S-bore were stamped with a "S" on the receiver to indicate the change.

[Sam]

On 3/5/2024 at 10:20 PM, Phil Carr said:

The best and safest way to determine what cartridge it takes is to do a chamber cast. I also always slug the barrel. Not hard to do and actually kind of neat to learn to do this. 
It very well may be 8x57. I copied this for information. This better details the differences. 
i recently camber cast and slugged the barrel of a friends rifle, a Combination German rifle.
His rifle was actually another cartridge of 8x57. I was determined to be a 8x57 JR . A rimmed cartridge.
 

 8x57JS, the "J-bore", was the original chambering for the Mauser. It had a bullet diameter of .318 inches and was a round nose deisgn. The 8x57IS, referred to as the "S-bore" was the later chambering with a new spitzer bullet with a diameter of .323 inches. Early rifles chambered for the J-bore and subsequently modified to fire the larger S-bore were stamped with a "S" on the receiver to indicate the change.

Thanks for the information. I never had to slug a barrel before; seeing how we always knew the exact caliber we had. I might look into this. Or I might sell the rifle and let the next person decide. 

[Phil Carr]

If you were in Tucson I would be happy to make a chamber casting and slug the barrel. I can walk you through slugging the barrel. Just use a lead cast bullet larger than the rifle bore. Use a little lubricant and a short wood dowel to start the slug into the bore,  and use the long dowel to tap the slug through the bore. I use a set of dial calipers to measure the slug. You can then determine the slug diameter. 

 

[Sam]

That doesn’t sound too complicated. Thank you.
 He had 4 boxes of these 8x57. This must have been what we shot about 45 years ago! 

[Phil Carr]

Im guessing you have a 8x57 JS chambered rifle. If a round chambers I bet you have the correct ammo. I would just slug it to be sure. ( an ounce of prevention is worth more than a pound of cure. Good luck looks like a fun rifle.

 

[whitewater]

The CZ actions are desirable. Looks like the military issue stepped down bbbl.  Always good idea  to have these old sporterized Mausers checked out by someone knowledgeable just in case somebody rechambered it to something else.  The 8 x 57 is one of the world's great calibers, just never caught on much in the US. Returning soldiers knew and  liked the 30-06 ballistics as it was used in several service rifles WWI and WWII vintage.