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Shooting a .30-06 Bannerman Mosin

Discussion in 'Rifle Country' started by Ian, Apr 1, 2013.

  1. Ian

    Ian Well-Known Member

    I took my life in my hands last weekend and put a few rounds through a Bannerman converted .30-06 Mosin (the actual firing starts at about 9 minutes in):



    Bannerman was lot like the Century of their day; a huge surplus arms company. When they bought up surplus US-made Mosins in the early 1920s there was no domestic source for 7.62x54R, so they converted a lot of the guns to .30-06 for the sporting market. Conventional internet wisdom is that these conversions are pretty dangerous and liable to explode, but I don't think that is realistic.

    The gun headspaced perfectly, and we found nothing when checking for overpressure signs. I was expecting a hopelessly inaccurate shooter, but it was actually pretty good (ammo was US M2 ball). The only target on hand was a 1/2 scale silhouette at 100 yards, and several shooters were making very consistent hits on it kneeling and offhand. If I was a hunter in 1925 I would have bought one. Certainly a lot cheaper than my Remington Model 8!
  2. Carl N. Brown

    Carl N. Brown Well-Known Member

    The warning about the Bannerman conversion is the thinness of the metal left over the forward part of the chamber.

    Since the 7.62x54R is fatter than the .30-06, the Mosin barrel was removed, the rear end of the barrel was lopped off, the barrel retreaded and chambered to .30-06, and reinstalled.

    I have seen a cross-section drawing showing the .30-06 chamber in a converted Mosin barrel and it was scary to me.
  3. offthepaper

    offthepaper Well-Known Member

    Anyone know how many of the US made Mosins were converted to 30-06?
  4. Slamfire

    Slamfire Well-Known Member

    I agree.

    Even without a wall thickness and stress analysis I am going to say that the reduction in chamber sidewall makes this conversion dangerous.

    It is not appreciated but the barrel carries more load than the receiver. Load is surface area times chamber pressure and that barrel is housing a three inch long cylinder. The total load is much larger than what the lugs have to support.

    Barrels carry load in the radial direction, such as shown in this picture.


    Reducing the thickness of the chamber around the cartridge case is unwise.
  5. cal30_sniper

    cal30_sniper Well-Known Member

    Does anyone have a scan of that overlay showing the chamber of the .30-06 cartridge on the reduced shank Mosin barrel? I think that picture might tell a thousand words as to the safety of this conversion.

    Ian, I sure hope you aren't ever planning on feeding commercial .30-06 through that rifle. The M2 ball ammo is not loaded that heavy, as it has to reliably function the Garand without hurting it. Commerical ammo might do some really bad things to an action that was already marginal with M2 ammo. I only ask because I found one of your threads from another forum last year where you said you never planned on firing the rifle.

    Please bear in mind that doing something once does not mean it is safe. Metal fatigue is very much cumulative, and you have no idea what that rifle has been through with previous owners. Just because it didn't fail the first time you shot it, doesn't mean it won't the next. I've never seen one of these rifles in person, but your pictures of the extremely short barrel shank made my toes curl. With an '06, you are dealing with an extreme amount of pressure, and in this case, a very thin barrel.

    Looking at cartridge dimensions, I can see why they didn't try to rechamber it to .30-40 Krag or .303 British, both of which would have been much safer. What I can't understand is why they went with .30-06 instead of .300 Savage. My guess is that a military surplus company probably didn't have any engineers on hand to tell them what a bad idea what they were doing was.
  6. NeuseRvrRat

    NeuseRvrRat Well-Known Member

  7. cal30_sniper

    cal30_sniper Well-Known Member

    Wow, that is quite a bit scarier than I imagined.

    Ian, I wouldn't shoot that rifle any more if I were you. You've tempted fate enough already.

    I've got a 1939 production 6.5mm Carcano that was later cut down and rechambered to 8x57 by H&K in Germany as a last ditch defense weapon. My Great-Grandfather traded it off of some Mexicans in Presidio, TX a long time ago. I've never fired it, and you couldn't pay me enough to, for the exact reason shown above. That Carcano has one of the thinnest barrels that I've ever seen, but the critical area of that bannerman conversion adjacent to the chamber is much worse in comparison.
  8. Carl N. Brown

    Carl N. Brown Well-Known Member

    From what I have read, even dedicated collectors and historians of Bannerman are not sure.
  9. hang fire

    hang fire Well-Known Member

    If thin wall chambers are dangerous, guess we should destroy all our high pressure lounden banger revolvers.
  10. kBob

    kBob Well-Known Member

    While in high school I had a local dealer actively hunting one for me.

    I planned to shoot GI ammo in it.

    Now that I have you all riled up.....I was planning on using it as an Agressor rifle (Opposing Force in military training) and use the same US .30 cal blanks in it we used in our M-1 Garands.

    I did use an bring back M44 for one session, but my attempt to make a blank using a 7.62x54 primed case and the powder from a GI .30 blank and painted in card board stopper failed for whatever reason. That M44 was the first Mosin I ever fired and even with ancient US hunting ammo it was a painful experience for someone used to rimfires and M-1 carbines.

  11. cal30_sniper

    cal30_sniper Well-Known Member

    Your what?

    I have a hard time imagining any revolver other than a .454 Casull could match the 60,000psi of commercial .30-06 loads.
  12. Scooter22

    Scooter22 Well-Known Member

    "Looking at cartridge dimensions, I can see why they didn't try to rechamber it to .30-40 Krag or .303 British, both of which would have been much safer. What I can't understand is why they went with .30-06 instead of .300 Savage. My guess is that a military surplus company probably didn't have any engineers on hand to tell them what a bad idea what they were doing was."
    Because they had allot of surplus 30-06 to sell.
  13. Ian

    Ian Well-Known Member

    I suspect the reason they didn't use .300 Savage is because it was basically brand new at the time. The caliber conversion was to use a cartridge that was popular and widely available, and while .300 Savage would have fit the bill in the 40s or 50s, it didn't in the early 20s.
  14. Ian

    Ian Well-Known Member

    FWIW, the M2 ball I was shooting has a chamber pressure of 50k psi, which is actually below the 7.62x54R standard of 52k psi.
  15. hang fire

    hang fire Well-Known Member

    Good luck putting a 60,000 psi 06 load in a Model 95 Winchester.
  16. cal30_sniper

    cal30_sniper Well-Known Member

    How about answering the first question before starting off on a new tangent?

    While extended use of high pressure loads are not recommended in the original 1895 rifles, the modern reproductions are more than capable of using them, mainly through the use of better steels. Even so, the use of full power .30-06 loads in an original 1895 will cause peening and bolt face setback, resulting in excessive headspace. This is bad for the rifle, but not dangerous to the shooter unless a grossly excessive headspace is allowed to proceed unchecked. Quite different from the scenario where the front receiver ring or barrel shank explodes in the Bannerman.

    Correct, as I earlier mentioned, shooting M2 ball makes this a very unsafe operation instead of an extremely unsafe proposition. If I'm not mistaken, CIP standard for the 7.62x54R is actually 57ksi. However, think of it this way. You are firing a cartridge that is very near the maximum pressure for the original design, but you are doing it with what looks like more than 50% of the metal removed from one of the most critical areas of the original design.

    Every time you fire any rifle, the metal expands and contracts around the chamber. Steel is elastic just like any other metal, and has a stress-strain curve. At a certain point in the expansion, the metal ceases to become elastic (i.e., returning to its original shape), and becomes plastic (will not return completely to its original shape). This is exactly what leads to excessive headspace when firing high pressure loads in older rifles. In the case of the bannerman, with all that reinforcement around the chamber removed, if the metal is reaching plastic deformation, it could very well fail altogether.

    Not to mention that you are operating with a factor of safety that is much, much lower than originally designed. Rifles are over designed, because cartridges are often accidentally overloaded, even from the factory. If you take away this extra factor of safety, you are shooting a ticking time bomb that is waiting for the first out of spec ammunition to come along and kill you.

    At the time the rifles were introduced, the use of early smokeless powders resulted in lower pressure ammunition than we see today. This is why the M2 ball is only about 52ksi. Later on, with much more advanced powders, designers were able to duplicate the performance of M2 ball out of the much smaller .308 Win case. Those same advanced powders were used in the .30-06, resulting in improved performance, but higher pressures than originally conceived. While the Bannermans may have been marginally safe to shoot when they were introduced, age, misuse, and the introduction of higher pressure commercial loadings is exactly the reason they SHOULD NOT be fired today. What little factor of safety they originally had is most likely completely gone at this point. The only reason you probably haven't heard of one blowing up yet is that wisely, nobody else is shooting them, due to the ample warnings in existence.

    In the end, its your rifle, and you can choose to do with it as you want, at the risk of your own life and limb. I only take issue with the idea that since you fired it a few times, it must be safe. That is simply not true. Even if the chamber was only slightly deforming each time the rifle was shot, the life of that arm could currently be measured in the tens of rounds or single digits, especially if you were ever to start firing .30-06 commercial rounds. Think of what the uninformed could do with such information before making blanket claims about the safety of a rifle which so many people over the years have advised against firing.
  17. cal30_sniper

    cal30_sniper Well-Known Member

    That makes sense. What a shame, because chambering in 300 Savage would have left a lot more meat in the barrel shank, pretty much eliminating any safety concerns of the Bannerman. Its also a unfortunate that all the other contemporary rimmed .30 cal cartridges are so narrow compared to the 7.62x54R. If they had been able to convert these to .303 Brit, .30-40, or .303 Savage, it would made a heck of a handy little sporter.
  18. Gunnerboy

    Gunnerboy Well-Known Member

    All im gonna say about these sweet conversions is 06 loaded subsonic is quite entertaining thru them.
  19. Lj1941

    Lj1941 Well-Known Member


    It looks to me like a grenade with the pin pulled and ready to blow.This is from a person who has 2 UNMODIFID 91/30S that I shoot every chance that I can!.:cuss:
  20. cal30_sniper

    cal30_sniper Well-Known Member

    I've done some back of the envelope calculations to amplify my point.

    Here's the assumptions:

    1. The barrel can be modeled as a thick-walled pressure vessel.

    2. The critical point is at the throat or neck of the cartridge. In the Bannerman, this is the point where the barrel has already stepped down to the thin section, but the chamber is still large enough to allow the neck of the casing to enter.

    3. The inner radius at the neck of the casing is ~0.34". This is from the neck diameter of a fired .30-06 case.

    4. The outer radius at the thin part of the barrel is ~0.75". I don't know this, I'm just guessing.

    5. The outer radius at the thick part of the barrel of a regular mosin is ~1.1". Again, I don't know this, it's just a guess.

    6. A military 7.62x54R has a maximum chamber pressure of ~52ksi.

    7. A commercial .30-06 round has a chamber pressure of ~60ksi.

    The Method:

    I will look at the hoop stress present at the point that is halfway between the inner and outer radius of the barrel at the critical point. That is 0.38" from the centerline of the Bannerman barrel, and 0.72" from the centerline of a regular Mosin barrel.

    The Results:

    Using the equations for a thick walled pressure vessel, I get a hoop stress in the Bannerman barrel of 44.9ksi, vs a hoop stress in the Mosin barrel of 18.3ksi. That means, firing a commercial .30-06 cartridge through a Bannerman rifle, you are exceeding its original design parameters by approximately 250%.

    Using the same equations, but assuming an M2 ball pressure of 50ksi, you get a hoop stress of 37.4ksi. This is still ~205% of the original design parameters of the Mosin barrel.

    Finally, lets look at the hoop stress present at the outer edge of the barrel for all three cases:

    Standard Mosin, 7.62x54R: ~11.0ksi
    Bannerman, M2 Ball: ~25.9ksi (235% original design parameters)
    Bannerman, .30-06 Commercial: ~31.0ksi (~280% original design parameters)

    Now do you see the danger?

    EDIT: I found the actual diameters for the counter of a Mosin barrel. The outer diameter of the barrel at the end of a chamber of a regular 7.62x54R Mosin is 1.139". The outer diameter of the thin part of the barrel at the throat of a .30-06 Bannerman is 0.776". This leads to the following numbers:

    Hoop Stress at inner surface of the barrel (0.340" from bore centerline):
    7.62x54R Mosin: 62.2ksi
    M2 Bannerman: 73.7ksi (118%)
    .30-06 Bannerman: 88.5ksi (142%)
    Double-charged 7.62x54R Mosin (104ksi chamber pressure): 124.3ksi (200%)

    Hoop Stress at the middle of the thickness of the barrel (i.e., halfway between the inner and outer radius)
    7.62x54R Mosin: 17.1ksi
    M2 Bannerman: 34.9ksi (204%)
    .30-06 Bannerman: 41.8ksi (244%)
    double charged 7.62x54R Mosin: 34.3ksi (200%)

    Hoop Stress at the outer surface of the barrel
    7.62x54R Mosin: 10.2ksi
    M2 Bannerman: 23.8ksi (233%)
    .30-06 Bannerman: (279%)
    double charged 7.62x54R Mosin: 20.3ksi outer (200%)

    As you can see, the outer half of the barrel of a Bannerman is experiencing more stress than a regular Mosin Nagant fired at twice it's normal chamber pressure, even when using M2 ball. NOT SAFE!
    Last edited: Apr 3, 2013

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