Manufacturing Specifications for 7.62x54R Mosin Nagants

[The Bolt Man]

Has anyone studied the manufacturing of the barrels for the various Mosin Nagant rifles? I ask this because there are so many of these rifles with what appears to be oversized bores. I have Russian and Polish examples with groove diameters running from .313” to .315”.

The only information I have been able to find that lists Mosin Nagant groove diameters indicates Russian groove diameters at .311” and typical Finnish groove diameters at .3095”. Most of us know when the groove diameter of a bore exceeds the bullet diameter, pressures fall and so does the velocity. Flame cutting and carbon deposits in the grooves increases and accuracy suffers.

I would like to see the actual manufacturing specifications for the Mosin Nagant rifle barrels. This would be something like .311” +.001 and minus .000”. It would help me greatly to know what the actual groove diameter is specified and the plus or minus tolerances are.

I can’t imagine specifications so sloppy as to permit groove diameters to exceed the desired .311” specification. Not all of the Russian Mosin Nagants were manufactured under the stressful demand of war time production and the Polish M44’s produced in the 1950’s have the same problem. I always thought the Polish rifles were much better quality than the Russian, but mine isn’t. It has a groove diameter of .315” plus. The Finn’s seem to have their bores sized correctly.

[rayjd2]

Remember that these rifles see years of neglect if not service. This takes a toll on a bore. Corrosive ammo, shoddy cleaning, these all take metal away.

In short: don't fret.

[zeebill]

The above is very true! Now you add in the fact that the workers were going 24 hours a day and more than likely a lot of the machinery to make the rifles was more than likely way past when it should have been thrown away and replaced. Look at the outside machining on some of the really bad times, do you think the inside machining was that much better? There was more than likely a great relief when they test fired and they just plain went off much less were 100% right in other ways. It is military machined in an armory running at 100%+ at all times. How good do you think they were able to get them. They had numbers to make for an hour, a day, and a week which if they failed to make they were off to Siberia or worse. Like the man said don't fret! Bill

[SA1911a1]

Just keep buying the rifles until you find one that meets your requirements.

[bunkysdad]

I am not surprised to hear of the variations you are mentioning. I don't really think that the Mosin has ever been considered to be manufactured with the same tight tolerances that we are accustomed to seeing in the Mausers, or U.S. firearms, or the fine Finns. I knew there was a reason why the Finns had to build their own barrels. Barrels made often in Switzerland no less. A quick inspection of the bolt compared to a Swedish Mauser bolt or Enfield bolt or any of the other Mauser bolts shows a different way of thinking in design and function. I give them credit for making rifles that work, were simpler to manufacture and operate, and thank them for storing them away for so long and in such vast numbers that when their economy tanked and they needed to move them that it was made possible for us to buy them. As far as gas blow-by or flame cutting, or loss of velocity I don't know if the workers in the machine shop dungeons of Russia knew much about all that stuff. You would think so, but I have seen a couple of old B&W videos on YouTube and the conditions look kind of rough. One video showed kids putting together 1895 Nagant revolvers. The Polish are usually considered to be the best of the carbines, but maybe that is because of the new like condition that we find them in. Nice wood, nice polished and blued receivers and barrels and so on, but maybe not so much in the barrel tolerances.
My thoughts on milsurps is different from many others. I have never slugged a bore. I have the items to do it. I am not being lazy and it doesn't take a lot of effort to do it. I did take a bore scope to one of my rifles and nearly coughed up a lung! So I no longer bore scope my rifles. I clean them, enjoy them, shoot them, heck sometimes I even watch TV with one of them. If they are less than perfect I still love em.

[docbob]

I have an Izhevsk 1941 that surely was made after June as it's typically rough finished on the outside with plenty of extra iron on the receiver. Yet, the bore is bright with crisp rifling and is .312". They seem to be all over the place, like most military bolt rifles. They weren't built for target shooting but to save the country from the Germans. One can only imagine the chaos with the enemy at the gates.

[The Bolt Man]

I think I understand where you guys are coming from with your ideas. By nature, I am the type of person that is investigative and asks questions while looking for answers based on facts. That is why I would like to know what specifications were used to produce the Mosin Nagants. Of interest would be the specs for the bore and groove diameter.

What bothers is the process of making a rifle barrel includes boring the barrel blank and there would be a maximum and minimum dimension. The final reaming of the bore uses a reamer that would start cutting at or slightly below the maximum dimension and would continue to be used until it wore enough so it would be cutting at the minimum dimension at which time it would be replaced. This is normal tooling and machining practice. The tooling for cutting the rifling grooves would use the same process, The groove cutter would start cutting at maximum groove depth and wear until it would be cutting at minimum groove depth at which time the cutter would be replaced. These are not hammer forged barrels.

This would suggest we should be seeing more Mosin Nagant barrels with bores that are undersized, BUT WE DON'T. WHY? We see just the opposite. So, are these oversized bores sloppy work, I don't think so. There appears to be some intent to produce oversized bores and I would like to know why. That is why I would like to see the manufacturing specifications. They could explain why these bores are the way they are.

[zeebill]

Go to 7.62x54r.net and look under specifications and that is the best I can do for you. Bill

[bunkysdad]

Yes I see what you are saying. As the reaming tool wears it would cause the bore to become smaller, not larger. Makes sense. Hmmmmm, dangit, now I am wondering too. Makes you wonder if they didn't start out with .315 dimensions to allow for longer use of the tooling, which would mean that a little gas leakage or blow by was acceptable for their standards.

[fintowin]

I work in a factory where we drill many thousands of holes on CNC machinery every day. Sometimes when a drill gets dull, it produces an over sized hole, and sometimes it will be undersized. It all depends on what caused the drill to fail. There are many variables that cause holes to be out of spec in regards to drilling, drill run-out being a big one. I think that Quality Control in Russia was probably near negligible, and many barrels left the factory without ever being inspected. Just my thoughts.

[Vendetta]

I doubt that 1940s wartime machining tolerances fall into a +.001/-.000" tolerance territory. I would suspect that based on gauging types available and material types that their tolerances would fall more into a +-.002" realm. Im typing this while sitting at a machine which from time to time has trouble holding a .+-.0005" tolerance and its 2015. Just a thought. Not to mention not a one of these rifles is unfired. Metal on metal wears a bore, and that wear is likely to show as an "oversized" bore diameter. Im sure that it was all "acceptable" to the Russians with Germany pounding on the front door.

[bunkysdad]

Except for the fact that rifling isn't done with a drill bit, so I just don't know. At least now I am back to my original thought that I don't want to bore scope my rifles for corrosion, and I don't really want to slug them either. If I have a problem that shows up on the paper at 100 yards, then I might rethink it on that rifle, but with my aging beady eyes, I am not sure I'll ever know for sure, so I just make sure that I have fun and if I don't have a great grouping then the range has a trash can handy to toss my target.

[Vendetta]

I completely agree with that BD. Im just happy shooting them. If I can drop them all inside a 6" circle great but I dont shoot Mosins or an C&Rs for groups. I have modern rifles for that. I shoot them for the feeling, nostalgia, and experience.

[A J]

Holding a Mosin in my hands gives me a profound respect for both the soldiers who fought with them as well as the factory workers who built them. I have served in combat and have worked in a factory. Both jobs sucked. Which was worse? Probably the combat deployment, but the factory job was a REALLY close second.

When I see a rough tooling mark on a mosin I wonder if some poor, hungry, arthritic old man made that mark when he was in his 16th hour of a work day. I think the same thing when I see my great grandfather's old pipe wrenches with well-worn handles and mushroomed back ends where he used them as hammers.

[A J]

Except for the fact that rifling isn't done with a drill bit, so I just don't know. At least now I am back to my original thought that I don't want to bore scope my rifles for corrosion, and I don't really want to slug them either. If I have a problem that shows up on the paper at 100 yards, then I might rethink it on that rifle, but with my aging beady eyes, I am not sure I'll ever know for sure, so I just make sure that I have fun and if I don't have a great grouping then the range has a trash can handy to toss my target.

I'm the same way, Brother. If I don't actually hit the target (which happens more than I care to admit) I still get a big charge from seeing that big explosion of dirt fly up! Yeah.... That's where I meant to shoot.

[The Bolt Man]

Except for the fact that rifling isn't done with a drill bit, so I just don't know. At least now I am back to my original thought that I don't want to bore scope my rifles for corrosion, and I don't really want to slug them either. If I have a problem that shows up on the paper at 100 yards, then I might rethink it on that rifle, but with my aging beady eyes, I am not sure I'll ever know for sure, so I just make sure that I have fun and if I don't have a great grouping then the range has a trash can handy to toss my target.

bunkydad,

You missread my statement. "What bothers is the process of making a rifle barrel includes boring the barrel blank and there would be a maximum and minimum dimension. The final reaming of the bore uses a reamer that would start cutting at or slightly below the maximum dimension and would continue to be used until it wore enough so it would be cutting at the minimum dimension at which time it would be replaced. This is normal tooling and machining practice. The tooling for cutting the rifling grooves would use the same process, The groove cutter would start cutting at maximum groove depth and wear until it would be cutting at minimum groove depth at which time the cutter would be replaced. These are not hammer forged barrels."

These Mosin Nagant barrels were cut rifled after the bore was bored, reamed, possibly honed. Then the grooves would have been cut.

I guess I am looking for information that is of little interest to the average Mosin Nagant owner. I have studied them for some time and the actual specification for the bore is something of interest to me. It is just that simple and I am still looking.

[rayjd2]

Someone on this board has a factory fresh, never fired M1891 from New England Westinghouse I believe. Search the showcase index, pm them. I'm sure they'll take calipers to the muzzle. That'll be the closest we can get to factory tolerances without... Maybe ask the child companies that made them? Couldn't hurt to try.
But remember that no matter what specs the U.S. factories were given, they were likely made to tighter tolerances than Russian Empire and USSR rifles.

[qz2026]

This is really a good post. I don't think there is a chance at all that there were not established tolerances (the original question), even with the Russians. Trying to acquire that information would be impossible unless one of our Russian members does some snooping in Russia for the answer. And, I can't imagine that there was no QA undertaken with a minimum of a representative sample based on manufacturing totals. Again, what those tolerances and QA records will probably be will forever be unknown. And, I would think that this was faithfully followed in the early versions of the rifle based on the myriad of inspection stamping on the undersides of the receivers and barrels. I recently saw this Dragoon on the other site that must have had a hundred stampings on the underside of the barrel alone. You see a distinct lack of stampings during the war years. I don't know if this means that the QA stopped or they didn't think there was time to actually "document" the inspections on the rifle itself. But, there must have been something. Sure, heads will roll if the product doesn't get off the production line in sufficient quantities but heads will roll, as well, if rifles start blowing up in the field or unit commanders find that accuracy is fully degraded. That's assuming unit commanders gave a rip...

I've never slugged the bore of any of my Mosins. I guess I never felt the need. Much like BD, due to my failing eyes, I can't blame the rifle for bad hits. I must admit thought that all the Mosins I have shot hit the paper - usually in center mass. I think these rifles did exactly what they were designed to do regardless of us knowing exactly what the tolerances were.

[bunkysdad]

Except for the fact that rifling isn't done with a drill bit, so I just don't know. At least now I am back to my original thought that I don't want to bore scope my rifles for corrosion, and I don't really want to slug them either. If I have a problem that shows up on the paper at 100 yards, then I might rethink it on that rifle, but with my aging beady eyes, I am not sure I'll ever know for sure, so I just make sure that I have fun and if I don't have a great grouping then the range has a trash can handy to toss my target.

bunkydad,

You missread my statement. "What bothers is the process of making a rifle barrel includes boring the barrel blank and there would be a maximum and minimum dimension. The final reaming of the bore uses a reamer that would start cutting at or slightly below the maximum dimension and would continue to be used until it wore enough so it would be cutting at the minimum dimension at which time it would be replaced. This is normal tooling and machining practice. The tooling for cutting the rifling grooves would use the same process, The groove cutter would start cutting at maximum groove depth and wear until it would be cutting at minimum groove depth at which time the cutter would be replaced. These are not hammer forged barrels."

These Mosin Nagant barrels were cut rifled after the bore was bored, reamed, possibly honed. Then the grooves would have been cut.

I guess I am looking for information that is of little interest to the average Mosin Nagant owner. I have studied them for some time and the actual specification for the bore is something of interest to me. It is just that simple and I am still looking.

I can't go back right now and read all this again right now but I thought I was agreeing with you. At least I think I was following you.

[Longcolt44]

When the bulk of these rifles were manufactured, if it would fit in the stock, load properly and when fired the bullet came out the right end it was off to the front lines. The Russians to this day are very secret about anything they make.