Help Needed: Mauser Oberndorf Model B Sporting Rifle

Sharps45-70

Sharps45-70

CGN Regular
Rating - 100%
40   0   0
Location
Edmonton
I just picked up this Model B Oberndorf factory sporting rifle. I really like the rifle and fell in love with this style of rifle as soon as I picked one up and handled it. I knew I had to have one of my own, and when this one came up with a Lyman sight, I grabbed it.

I need a hand with a couple things. I honestly don't want to purchase a $400 John Speed reference book right now, so a hand deciphering the barrel markings would be great. From what I can tell so far, by serial number it is 1914 production, and the bore diameter would need .318 bullets. What do the other markings mean?

Finally, where can I find .318" bullets in Canada? I don't cast and don't want to get into that if I can help it. Is swaging .323" bullets an option?

Thanks for any help you can provide :)

qrQ6JaE.jpg

1Y9hB5D.jpg

5gGrE3W.jpg

cGMr8VP.jpg

3mU72Tc.jpg

qnHH6e7.jpg
 
I'm no expert but the 7,85 and 8,15 are, I believe, the bore and groove diameters and I believe 360 is the twist.

7,85mm = .309"
8,15mm = .321"

360mm = 14" Twist.

32 Special Bullets should be a good fit.

Guess the question is is it a 57 or 60mm case length.
 
Do a chamber casting of the neck and throat... if the throat will accept a .323" bullet, you can shoot a .323 bullet... it will swage to what ever quite quickly.
 
Roger that on the bore diameter. Will do a chamber cast and find out.

Does anyone know what the other markings are? The various proofs or the 156,14?
 
Crown B and Crown U are standard pre 1924 proof marks from Germany.

I *think* the 156,14 is the original "gauge" and the 7,85 8,15 360 was added later. Pure speculation but it may be chambered in 8.15x46mm as if the 360 is the twist it seems awfully slow for the 8x57.

Please update after you do the chamber cast.
 
MiG25 said:
Crown B and Crown U are standard pre 1924 proof marks from Germany.

I *think* the 156,14 is the original "gauge" and the 7,85 8,15 360 was added later. Pure speculation but it may be chambered in 8.15x46mm as if the 360 is the twist it seems awfully slow for the 8x57.

Please update after you do the chamber cast.
Click to expand...

This is what also was worrying me. It seemed like I wouldn't be firing the normal big 8mm projectiles like I was hoping, but who knows. I found I don't have any cerrosafe anymore, but I will try some 8x57 brass I have on hand to see if it chambers. A 10mm difference in length should be pretty obvious. Worst case I have to order some more to cast.
 
Your rifle dates to 1914. The calibre designation on the barrel ( 8.0N) I'm pretty sure refers to the 8x57. If it were 8.15x46 you would be able to tell from the extractor: it had a smaller claw for the rimmed cartridge. I don't have a picture I can post handy. The 8.15 in the proof marks converts to .321", so as long as the chamber neck and throat dimensions allow it, I think you would be safe working up a load with .323" bullets.
 
A chamber and throat casting with cerrosafe will for sure be the "best" way to ID what that is chambered for. Another possibility is to use soft lead ball and "slug" that bore - even a couple inches into and out of the muzzle - will give you a "groove" dimension as another clue to what the bullet size might be - does not really help with the chambering though.

From somewhere (Internet??) I had read that most German military rifles were converted to use .323" bullets, but that private gun makers may have been using .318" groove diameter barrels into the 1920's or so. I have never owned a .318" groove 8x57, so I do not know if special sizing die needed to load or not, or if the neck diameter of loaded round is different or not. I am sure that I read that the bore diameter (top-to-top of rifling) was never changed - just the grooves made deeper. I may have that mixed up ...
 
^isn’t it acceptable because of this to shoot .323 bullets at lower velocity? I’ve heard this is the reason why American ammo and load info is often at 30/30 velocity levels? They would chamber because all that changed is the grooves right?

If what you’re saying is right and I think it is would you be able to load a 318 bullet with modern dies and still have neck tension? This seems off but I have no clue what I’m talking about

Gun looks great btw, would love to get my hands on one like that with a 323 bore
 
Confirmed .323” bullet needed. Slugged at .322” from my measurements. What a relief! 8x57 brass chambers fine as well, so looking forward to shooting it with normal ammo.
 
Sharps45-70 said:
Confirmed .323” bullet needed. Slugged at .322” from my measurements. What a relief! 8x57 brass chambers fine as well, so looking forward to shooting it with normal ammo.
Click to expand...

Right on, can you also measure the twist to compare it to the "360" stamp? 360mm would equal 14".
 
conor_90 said:
^isn’t it acceptable because of this to shoot .323 bullets at lower velocity? I’ve heard this is the reason why American ammo and load info is often at 30/30 velocity levels? They would chamber because all that changed is the grooves right?

If what you’re saying is right and I think it is would you be able to load a 318 bullet with modern dies and still have neck tension? This seems off but I have no clue what I’m talking about

Gun looks great btw, would love to get my hands on one like that with a 323 bore
Click to expand...

Yes - American SAAMI was apparently concerned that North Americans could not or would not tell the difference between German 8x57I (or J) marked ammo and 8x57IS (or JS). An alternate story that I read was that USA wanted to make their own 30-06 appear so much better than the German round. I do not know which story is correct.

So, many dozen years after Germany had been making this round, SAAMI gave it a "new name" - for North Americans - is called 8mm Mauser - and has much lower pressure standard than the German (or European CIP) rounds. The SAAMI 8mm Mauser has .323" bullets - and loading is mild enough that SAAMI thought it was okay to fire in a rifle with .318" groove or .323" groove. Some makers, like PPU, on their website - offer both European 8x57JS ammo and also 8mm Mauser ammo - in most cases several hundred feet per second different muzzle velocity, loaded with the same bullet. From their numbers, PPU 8x57JS is NOT the same as PPU 8mm Mauser. I have some factory Federal ammo - labeled 8mm Mauser - so I expect that is SAAMI compliant - in other words, the "mild" stuff - although I have never run any over my chronograph.

As a side-note - I wanted to reproduce some WWI 30-06 ammo for a couple WWI 30-06 rifles. Somewhat shocking to me, WWI 30-06 ammo - the 1906 round - was only 2,700 feet per second with 150 grain bullets - what they fought WWI with. With improvements in powder, today we expect to get at least that velocity with 180 grain bullets, often more than that in 24" barrels. The German military load, adopted in 1905, used 154 grain bullets at 2,880 fps.

For a while I thought I was getting an 8x57I rifle - I was able to get some Woodleigh and Norma bullets that are .318" diameter. For reloading those, it was suggested to try re-sizing brass in a normal FL sizer, without the expander rod - it was assumed that might leave the neck "tight enough" for the smaller diameter bullets. As it turned out, the rifle had .323" grooves, so I never tried to re-load the .318" bullets into "8x57" cases.
 
Last edited:
Potashminer said:
Yes - American SAAMI was apparently concerned that North Americans could not or would not tell the difference between German 8x57I (or J) marked ammo and 8x57IS (or JS). An alternate story that I read was that USA wanted to make their own 30-06 appear so much better than the German round. I do not know which story is correct.
Click to expand...

The alternate story you mentioned is some horse pucky.
They just didn't want anyone to shoot full power 8x57js (.323 projectile) in an 8x57j rifle (.318 projectile). Obviously dangerous.
 
You must log in or register to reply here.
Back
Top Bottom