Steyr M95 bore diameter.

I didn't see a Mannlicher or Austrian sub forum so I thought this would be a good place to put this, if I'm simply blind please feel free to move it. I've been curious about this ever since I picked up my Steyr M95 or I guess M95/30 technically and started researching them. Mine has a matching barrel/reciever but all other parts are mismatched. The 1917 dated barrel has the front sight base integral with the barrel so from what information I've found this was originally a carbine length barrel and not one of the cut down rifles which had a banded front sight pressed on when they switched over to the 95/30. Now heres the big ? I haven't got around to slugging the bore yet but from my readings the 8x50R used a .323" bullet yet the 8x56R uses a .329 bullet. So going by this information this barrel originally was intended for .323 bullets. Therefore if they simply rechambered these to 8x56R wouldn't that .006" increase in bullet diameter drastically increase pressure? Such as the issues stemming from firing .323 bullets in a .318 bore Gewehr 88? Or did they somehow go back in and rebore these barrels when they rechambered and rebuilt the guns?

By using incorrect information , you will make incorrect assumptions . The M-95 bore Groove dia was always .329 . The .323 dia long rn bullets just rode the lands . This was common with all early military rifles . Accuracy was good enough , pressures were down and velocity was up . The Germans never used a .318 bore , nor a .323 dia bullet in Gew-88 rifles . The Gew-88's .3188 dia long rn bullet rode the lands on a .321 groove . Later the Germans switched to a larger short .321 Spitzer bullet , as a short or boatail bullet will not ride the lands as well or produce as much pressure as a long bullet . The M-95's later bullet was a .3286 boattail for machine guns , but would still work in the rifle's .329 bore.

Why undersize bullets in barrels Bob? Was it because there still was BP being used? An offshoot of that? That gave the BP buildup a place to go?

As stated before . The undersized bullet made less pressure and produced more velocity because of the lower bore friction . Accuracy was good enough . Everyone wanted to be able to out range their enemies . That is why they used 2000 + meter sights and volley fire .

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Originally Posted by bob q

By using incorrect information , you will make incorrect assumptions . The M-95 bore Groove dia was always .329 . The .323 dia long rn bullets just rode the lands . This was common with all early military rifles . Accuracy was good enough , pressures were down and velocity was up . The Germans never used a .318 bore , nor a .323 dia bullet in Gew-88 rifles . The Gew-88's .3188 dia long rn bullet rode the lands on a .321 groove . Later the Germans switched to a larger short .321 Spitzer bullet , as a short or boatail bullet will not ride the lands as well or produce as much pressure as a long bullet . The M-95's later bullet was a .3286 boattail for machine guns , but would still work in the rifle's .329 bore.

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Thanks Bob, that definately makes sense. I feel like a lot of this "incorrect information" comes about because someone hears about it or observes one example and then parrots it as gospel and over time it becomes the norm. I've come across several guns in my brief time collecting that were all matching #'ed or provenance was otherwise known yet things didn't quite match what was written in reference books when it came to small cosmetic and/or engineering changes, or markings. It makes me wonder how often these reference books are just downright wrong. Now I no longer have to sit here like I've been doing for two weeks trying to figure out how they either A. Swaged a bullet .006" in firing without a kaboom. Or B. Went back through those bores and were able to line up just so and not ruin the rifling to rebore them. I supposed the answer should have been a little more obvious, but alas that is not always the case.

They also believed the bullet would 'obliterate' into the bore, i.e. the base of the round would expand into the grooves creating a seal. Most bullets of that era were open based 'cupped' bullets which would expand to some extent (for example I have some 6.5 Carcano surplus bullets which clearly show this type of design). This mentality is largely a carry over from black powder rounds which were primarily lead bullets (i.e. expanding more than a jacketed bullet). Much like the belief that they needed long barrels for velocity (a very large factor for black powder rounds, not so much for smokeless powder rounds). Back then the understanding of smokeless powder and building firearms based around it was pretty limited indeed (think Gewehr 88 and issues like lack of proofing, rifles blowing up in service, etc.). It took a while for them to gain a clear understanding of how it worked, and many wrong theories had the spotlight for a bit due to the fact they hadn't been disproven (think about things like early semi-auto experimentation and the fears a hole drilled in the barrel would greatly effect gas-pressure and reliability, etc.).

Another side note in the Austrian case originally the 8x50r round was a black powder round, and the barrels would have been designed accordingly. I am pretty sure both the M1888 Mannlichers and M95 Mannlichers had the same bore dimensions and twist rate (but not thickness), so that is also a factor.

The knowledge base for early bolt actions specifically the Gewehr 88s, and Mannlicher firearms is very limited indeed. Many wrong things have been printed over the years, and due to how many refurb programs happened to these rifles over the years it is hard to find a 'pure' example. These rifles are kinda find your own truth, rather than trusting what is in the books.

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Originally Posted by Eaglelord17

They also believed the bullet would 'obliterate' into the bore, i.e. the base of the round would expand into the grooves creating a seal. Most bullets of that era were open based 'cupped' bullets which would expand to some extent (for example I have some 6.5 Carcano surplus bullets which clearly show this type of design). This mentality is largely a carry over from black powder rounds which were primarily lead bullets (i.e. expanding more than a jacketed bullet). Much like the belief that they needed long barrels for velocity (a very large factor for black powder rounds, not so much for smokeless powder rounds). Back then the understanding of smokeless powder and building firearms based around it was pretty limited indeed (think Gewehr 88 and issues like lack of proofing, rifles blowing up in service, etc.). It took a while for them to gain a clear understanding of how it worked, and many wrong theories had the spotlight for a bit due to the fact they hadn't been disproven (think about things like early semi-auto experimentation and the fears a hole drilled in the barrel would greatly effect gas-pressure and reliability, etc.).

Another side note in the Austrian case originally the 8x50r round was a black powder round, and the barrels would have been designed accordingly. I am pretty sure both the M1888 Mannlichers and M95 Mannlichers had the same bore dimensions and twist rate (but not thickness), so that is also a factor.

The knowledge base for early bolt actions specifically the Gewehr 88s, and Mannlicher firearms is very limited indeed. Many wrong things have been printed over the years, and due to how many refurb programs happened to these rifles over the years it is hard to find a 'pure' example. These rifles are kinda find your own truth, rather than trusting what is in the books.

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I believe "obdurate" is the word, and yeah I understand what you mean. Last summer I pulled down some fairly new 7.62x54R steel cased ammo that came in unmarked 40 rd white cardboard boxes. I can't remember the headstamp. I wanted to try then out in my 1938 M91/30. Strangely enough they were a 150gr. hollow base FMJ, possibly for that very purpose of obduration? I never slugged the bore of that rifle but it shot as well as I could hold it with Sierra and Hornady 150gr. FMJ's. Strangely enough it would consistently give me 150-250fps less with the hollow base bullets of unknown origin. I shot about half of the 50 or so I pulled and chucked the rest. Unless I put them in a box somewhere, hard telling now.

First, let me say that all old rifles need to be treated as individuals. Even if made to a specific standard. Please consider that most of the old milsurps that concern us were made long before CIP or SAAMi were set up!

For what it's worth, here are the bore and groove dimensions from the German "Masstafeln" = dimensional tables. These are the values used by proof houses over here, regardless of what you might have read in the English-speaking world. ANYTHING THAT YOU READ ELSEWHERE, ESPECIALLY WHEN GIVEN IN INCH DIMENSIONS, IS DERIVED INFORMATION AND SHOULD BE TREATED WITH APPROPRIATE CAUTION. The inch values given below are approximations!

I apologize for shouting, but it has already been correctly pointed out that derived information may contain errors.

8x57J - NOT the old Gew.88 bore. A derived standard for civil rifles only. See later correspondence. Note the use of J, not I, to avoid confusion with the number 1.
Bore / Groove 7.80 / 8.07 mm = 0.307 / 0.318

8x57JS - the "classic" Gew. 98 /Kar 98. S stands for "Spitzer" bullet, already mentioned in previous posts.
Bore / Groove 7.89 / 8.20 mm = 0.311 / 0.323

8x50R - the original Austrian Mannlicher miltary caliber. Most altered to 8x56R M30S
Bore / Groove 7.95 / 8.35 = 0.313 / 0.329

8x56R M89 Portuguese Kropatschek. Sometimes confused with the Hungarian 8x56 (below).
Bore / Groove 7.85 / 8.20 = 0.309 / 0.323

8x56R M30S - the later Hungarian M(odel 19)30 S(pitzer) caliber.
Bore / Groove 7.95 / 8.35 = 0.313 / 0.329

So you can see, there is no such thing as a simple "8mm caliber". Add in wear, refurbishment, and just plain Bubbaring, and it is clear that it is vital to measure all old milsurps before attempting to shoot them.

Your Gew-88 bore information is not correct . Your posting of that is the exact example of what I was talking about . The German military NEVER used a .307 -.318 bore . That is a civilian bore size . The Gew-88 bores sizes were as follows : 1889- .3138 - .3208 [ rifling was too shallow , wear was a problem ] ,,,,,,, 1890- .3108 - .3208 [ rifling made deeper by making bore hole smaller ] ,,,,, 1895 1/2 .3108 - .3238 [ the final military bore size used through WWII ] . I own over 50 rifles of all makers and years and they all match that , as do the original German military testing documents .

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Originally Posted by bob q

Your Gew-88 bore information is not correct . Your posting of that is the exact example of what I was talking about . The German military NEVER used a .307 -.318 bore . That is a civilian bore size . The Gew-88 bores sizes were as follows : 1889- .3138 - .3208 [ rifling was too shallow , wear was a problem ] ,,,,,,, 1890- .3108 - .3208 [ rifling made deeper by making bore hole smaller ] ,,,,, 1895 1/2 .3108 - .3238 [ the final military bore size used through WWII ] . I own over 50 rifles of all makers and years and they all match that , as do the original German military testing documents .

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Before this turns into a shouting match and goes completely off course I'm just gonna say I got the answer i was looking for,and I'll likely be sticking to my .329 cast bullets. They shoot as well as I can do and that's good enough for me. I did shoot one box of the PPU stuff and will say it's not the most comfortable shooting round in a light little carbine.

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Originally Posted by bob q

Your Gew-88 bore information is not correct . Your posting of that is the exact example of what I was talking about ...

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Thank you bob q! You are correct.
The information I gave is the official standard dimensions from the "Masstafeln" for 8x57I, but I should not have written "Gew. 88". It all just confirms that measurement beats theory!

Final contribution from me on this topic in this thread:

Bob q was perfectly correct, and it seems that the greatest use of my contribution was to demonstrate how one can fall into using inappropriate information!
I looked up the 8x57J section in the Dynamit Nobel "Wiederladen" manual (which contains the "Masstafeln") and it appears that whereas the mlitary altered the bullet to the 8.20mm /0.323" "S" type to fit the bore, civilian makers reduced the bore to fit the older 0.318 roundnose bullet. So the published 8x57J standards are only intended for civilian rifles, not military ones. A good example of how standards are sometimes derived "after the event", with resulting confusion for later users, me included!