US adopts 6mm caliber in 1930s

Discussion in 'Alternate History Discussion: After 1900' started by wiking, Oct 8, 2019.

  1. MichaelWest Well-Known Member

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    Indeed. I think the conservative nature of Army procurement might still see .30-06 prevail, but I would vote for the .276. It actually makes the BAR more sensible, full-auto-ish, Mg-ish, potent round, the partner to this new "lightweight". It lets the Army dither on about replacing the M1919 with a true GPMG the infantry can carry. As wiking points out, the .276 Garand might sideline the M1 Carbine, thus the Army has .45 M1911/Thompson, .276 Rifle/Carbine, and .30-06 BAR/MG. Not logistically far from OTL. I will not predict a SAW at this point but things like the Johnson LMG might get a better look at, the .276 might spur development of a better BAR weapon for the Squad. Of course that seems to suggest the 6mm arguments here argue for .276, rather than a new round as such. Would the USMC persist with the 1903? It occurs to me they might not prefer this new rifle or its round.
     
  2. Crowbar Six Well-Known Member

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    The US army didn't really use the Thompson until later on. The US Marines and Navy had some, but Colt only made 15000 in 1921 and all the subsequent models were upgrades/modifications of those until the US military restarted M1928A1 production in the late 30's and then introduced the Thompson M1.

    A .276 Garand would not have sidelined the M1 Carbine as there was still a requirement for a light handy weapon to equip truck drivers, mortarmen, radio operators etc. The US army was not happy with 1911's or Thompsons in that role as they didn't have the required range or accuracy and even a Garand in .276 is too big and heavy for that so something like a M1 carbine is always going to pop up sooner or later given the way the US military was thinking.

    As for .276 stimulating a true LMG/GPMG in US service, you would first need to bang a lot of heads together in the Pentagon and Springfield, the US seems to have ignored the introduction of the ZB26/30/Bren family and the MG34 along with the tactical flexibility they offered. The M1919 was a good weapon (for a vehicle) or in a MMG role and the BAR was a weapon, sadly they were both deficient when it came to modern warfare.
     
  3. Dave Shoup Well-Known Member

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    With no AEF, the US Army is looking at replacing about 1 million M1903s in the 1920s-30s, rather than having a stockpile of 3 million M1903s and 2 milion M1917s, so procuring one million S/A rifles in .276 (7 mm) is much more in the realm of possibility.
     
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  4. Dave Shoup Well-Known Member

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    Conservative, or just having to deal with the reality of peacetime budgets and the Depression?
     
  5. SsgtC Ready to Call it a Day

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    Depends on budgets. The USMC got treated like the red headed step child of the services during that time. Hell, we still get treated like that! Whether the Marines make the switch or not depends on how budgets are.
     
  6. perfectgeneral Velocireader. Highly socially inept. CMII Donor

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    How about a nice Italian round?

    6.5mmx50mm_Carcano_(boat_tail_spitzer).jpg
    The Carcano (updated)

    USMC Navy 6.7x50mm
     
    Last edited: Oct 10, 2019 at 9:10 PM
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  7. Some Bloke Well-Known Member

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    Maybe the USN and USMC never ditch the Lee round.
     
  8. Peg Leg Pom Well-Known Member

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    Inter service rivalry Vs US Treasury?
     
  9. wiking Well-Known Member

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    Not the .276 Garand, just a .243 Garand. The 7mm Pedersen was too powerful to make it an M1 Carbine replacement, the 6mm version would be light enough to do both roles though.

    I suppose if they adopt either the .276 Garand or keep the .30 version then they might opt for a SCHV Carbine assuming that they still heed the report from OP. Then we might see a .20 caliber M1 Carbine, later on in the war with select fire and a 30 round magazine. That would be a true assault rifle.
    In fact something very similar to what a .20 caliber + .351 WSL rimless case cartridge would be exists now:
    https://en.wikipedia.org/wiki/.20_VarTarg
    Granted though it's performance relies on high energy modern powders to get to 1000mps at the muzzle, so not necessarily practical in WW2 from that sized case and uses a 24 inch barrel, but it shows what could be possible. By all accounts even the most powerful .20 caliber cartridges with 1200mps muzzle velocity are very low recoil and aren't hard on the barrel of a rifle, so would make for a very controllable automatic weapon cartridge.

    Not even just that, but the FN BAR modifications:
    https://en.wikipedia.org/wiki/M1918_Browning_Automatic_Rifle#Belgium
    QC barrel, simplified construction and takedown, and better rate reduction mechanism. That's not even counting the belt feed options a few people developed for the weapon. Forget the competition to the BAR even, just the modernization efforts for the BAR could have made it a cheaper, easier to make weapon, that worked better than the base version. Really kind of odd considering even the Soviets were able to develop a swap-able belt feed mechanism for the DP-28.

    That would be the easiest option in the long run, but difficult to pull off in the short run.
    I'd suggest have the French adopt their 6mm cartridge/SLRs that came out of their modernization project, but that was arguably only ready years after the LN was dropped.

    Plus the 6mm LN cartridge had issues beyond that which would be worked out with improvements in powder and barrel metallurgy:
    https://en.wikipedia.org/wiki/6mm_Lee_Navy
    It was of course adaptable, but that would mean significantly changing the case production lines anyway.
     
    Last edited: Oct 9, 2019 at 9:00 AM
  10. wiking Well-Known Member

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    I like. Even better if it worked in the Italian naval assault rifle:
    https://www.reddit.com/r/ForgottenW...he_65mm_scotti_naval_model_almost_an_assault/
    https://guns.fandom.com/wiki/Scotti_Naval_rifle
    https://books.google.com/books?id=z3O6DQAAQBAJ&pg=PT1395&lpg=PT1395&dq=Scotti+Naval+Model&source=bl&ots=WLV8-goThJ&sig=ACfU3U29GBMqTo4iGCuAGwynfxgHTXhn6g&hl=en&sa=X&ved=2ahUKEwiGkrT3mo_lAhVCEawKHRN6BloQ6AEwD3oECCsQAQ#v=onepage&q=Scotti Naval Model&f=false

    Why are navies the ones being innovative in rifle design???

    Congress already allocated the money.
     
  11. Peg Leg Pom Well-Known Member

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    Boarding actions are very close quarters combat where even a little advantage can make a huge difference. (And the one's making the choices aren't in love with their horses) It helps that a navy by its nature is very technology orientated.
     
  12. wiking Well-Known Member

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    Was that still an issue in the 1920s-30s?
     
  13. marathag Well-Known Member with a target on his back

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    The Army was blissfully unaware of what other countries were doing with the BAR, like QD barrels and belt feed.

    I agree fully, A 10 pound .276 Garand is still not a replacement for a 5.5 pound Carbine when you are replacing pistols
     
  14. Peg Leg Pom Well-Known Member

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    Navies stop and search ships all the time, and in the inter war period spent a lot of time and effort attempting to put down piracy in China.
     
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  15. marathag Well-Known Member with a target on his back

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    Per the 6mm Lee Navy, the ammunition costs were little different from other centerfire cartridges when the 6mm Lee was done as the .220 Swift.in 1936.

    Whats expensive in 1900 wasn't always expensive a few decades later, thanks to improved brass drawing technology that developed during WWI
     
  16. tomo pauk Well-Known Member

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    I'd say - go for it. Will make the ITTL M1 Garand weight less, more ammo can be carried for the same weight, and we'd soon see a proper LMG based on that ammo. Also easier to make and use a full-auto rifle around the intermediate ammo than aroudn a full power ammo.
     
  17. SsgtC Ready to Call it a Day

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    To a point as @Peg Leg Pom points out. The Naval Services also had to consider landing operations for their Ship's Marine companies and landing parties. For example, the American occupation Vera Cruz in 1914.
     
  18. Some Bloke Well-Known Member

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    Wasn't that the bullet that killed JFK?
     
  19. ShockTrooper262 Well-Known Member

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    A 6mm round might actually be able to feed properly in the T10/T23E1 LMG that ordinance were messing around with in the late 1930s, that would pretty much give the US the best LMG of ww2.
     
  20. Peg Leg Pom Well-Known Member

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    Oct 18, 2009
    How about when they adopt the Springfield the Navy and Marines turn their Lee Navy's over to what becomes the US Coast Guard. As a floating police force they don't need front line rifles. By the mid to late 1920's these rifles are wearing out and the CG has to deal with the Mafia rum runners so they look for a replacement and concerned about Thompsons but not wanting to look like gangsters themselves opt for a Semi Auto in their now standard calibre of 6mm Lee Navy. Being cheaper than the Thompson first the Marines and then later the US Army opt for this SLR instead of spending $200 a pop on Tommy Guns, later adding a select fire version.