WI: M1 Garand designed around .250-3000 cartridge

Discussion in 'Alternate History Discussion: After 1900' started by tomo pauk, Mar 14, 2019.

  1. tomo pauk Well-Known Member

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    The .250-3000 round, designed in 1915, was produced by 'Savage' company.
    Here we have the designer and manufacturer have no problems with US Army using it, as long as they have a sizable contract for supply. I'm not suggesting this cartridge as be-all end-all, just picking up something available in the period the self-loading rifle was being designed for the Army. Nor I'm suggesting that ww2 will end in Allied victory by 1943.
    After the lenghty intro:
    - what weight and length we can expect for the ALT M1?
    - scale of issue?
    - possible spin-offs before 1945?
    - earliest automatic weapon with this round?
    - M1 Carbine is still developed?
    - what might be reasonable/feasible answers by Germany, Japan, Italy, UK, USSR once they get good data on the rifle, and/or acquire the examples of it?
    - post war development & spin-offs of both infantry firearms and cartridges?

    The .250-3000 does not to have fire at actual 3000 fps, I'm okay with a bit lower MV when heavier bullet is used.
     
    Last edited: Mar 14, 2019
  2. hardrada55 Well-Known Member

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    I expect that it is more likely to see an earlier iteration of a cartridge like the 7.62x51 through an earlier "necking up" of .250-3000 to .30 caliber as was done in 1920 with the .300 Savage cartridge. Whether .250-3000 or .300 Savage is used, only a negligible difference in weight and length in the M1 would occur. I don't think the US Army will be happy with their decision if the adopt the .250-3000 as a military cartridge. Bullet weight is limited and thus down range ballistics is not as favorable and that does not fit in with the thinking of that era. M1 Carbine was still needed and still developed as historically done. .250-3000 bullet of .257 diameter is similar enough to the diameter of the 6.5mm (.264 + or -) that it will not effect other countries decisions made about their existing Army cartridges. Japan and Italy are still going to try to abandon their 6.5mm national cartridges for something bigger, i.e. 7.7.mm and 7.35mm. Use as the military cartridge for the U.S.A might significantly increase .250-3000s popularity around the world as a sporting cartridge.
     
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  3. tomo pauk Well-Known Member

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    Seems like the .30-06 fired projectiles twice as heavy as it will be the case for the .25-3000 on a tad lower MV, so weight of the ALT M1 can be significantly lower.

    The .250-3000 is very similar to the 6.5mm Grendel, muzzle enegy wise, that is renown for good balistics. Also, no worse than 6.8 SPC.
    Soviets, Germany, UK, France - neither has a 6.5mm or similar cartridge in use (apart from token use of Japanese 6.5mm by Russia/SU and ww1 UK).
    Semi-auto rifle that use low power rifle cartridge might inspire Japanese and Italians.
     
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  4. Cryhavoc101 Well-Known Member

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    On the LMG front had a new round been adopted for the principle service rifle then its probable that BAR replacement would be 'sought'

    An obvious choice would be the Johnson LMG chambering for this new cartridge as its design was partially based on Johnsons efforts on his entry for the SL service rifle competition thatw as won by the Garand

    By all accounts it was a good gun but did not get the orders necessary to keep it in service once existing weapons wore out

    In this case needing a weapon in a new calibre and not being able to soldier on with the BAR might see this weapon get pushed into mass production
     
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  5. Questerr Well-Known Member

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    I just can’t see the cash strapped 1930’s Army adopting a new rifle cartridge that requires also refitting all of their automatic rifles.
     
  6. tomo pauk Well-Known Member

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    Refitting of existing automatic weapons is not a requirement.
    The .250-3000 is not a new cartridge, US Army almost adopted the actually new .276 Pedersen.
     
    Last edited: Mar 14, 2019
  7. wiking Well-Known Member

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    They were planning on it with the .276 Pedersen until they realized they could still use the .30-06 in a semi-automatic rifle. That meant they were prepared to adopt a new auto-rifle chambering as well.

    Edit: sorry, though this was 6mm, not 6.5mm.

    The .25-3000 nearly matches the requirements for a 6mm military cartridge set out in the 1990s by Stanley Crist in the Infantry Journal:
    http://www.g2mil.com/6mm_optimum_cartridge.htm
    https://en.wikipedia.org/wiki/6mm_Optimum
    https://en.wikipedia.org/wiki/.250-3000_Savage
    With a more modern powder achieving 2900 fps muzzle velocity is really no trouble.
    Even with powders of the period with a 24 inch barrel they could get up to very near 2900fps:
    The Garand had a 24 inch barrel IOTL:
    https://en.wikipedia.org/wiki/M1_Garand
    So effectively the .25-3000 is exactly a '6mm Optimum' cartridge in the M1 Garand. You could certainly have a lighter rifle, as the M1985 Lee Navy, which fired a relatively similar cartridge was about 3.77kg:
    https://en.wikipedia.org/wiki/M1895_Lee_Navy

    The difference though in the long stroke gas piston system would certainly up that, but with a 4 inch shorter barrel the Garand would save a bit of weight there.

    So a 4kg M1 Garand should be easily do-able, which means a rifleman could carry at least double the ammo load compared to OTL.

    Not sure the Johnson LMG would be the right way to go with the side mounted magazine, but something like it would be better than trying to make due with the BAR. Not only would it weigh a lot less, but would be cheaper to make.

    Of course that's assuming the Garand isn't made select fire and magazine capable, which might well make an automatic rifle/magazine fed LMG redundant to the American rifle squad. With a 4kg rifle the recoil of the .25-3000 cartridge should be very mild, especially by the standards of the day, which would make automatic fire very controllable. The only issue would potentially be overheating.

    However to have something so actually ideal would require a lot of hindsight, as the US army had already killed the 6mm Lee Navy based on faulty assumptions about future needs. But handwaving that, the M1 Carbine might well never be developed and instead a carbine version of the M1 Garand would be viable:
    https://www.luckygunner.com/lounge/m1-tanker-garand/

    [​IMG]

    I doubt the Axis powers could do much with matching it considering that they were already in a shooting war and caliber switching was impractical. I guess maybe the Germans could try something in 6.5mm given how many nations they occupied that used rifles in that caliber. The existing 7.92 Mauser already had a development that mounted a 6.5mm bullet on the necked down cartridge, so you could rebarrel existing equipment to work with it. With a 100 grain bullet though it would be pretty damned hot, as the 6.5mm Swedish cartridge shows (the ballistics matches that of the 6.5mm Mauser) as it had a 970m/s muzzle velocity with that weight of bullet. They'd probably have to shoot for a 120 grain bullet to get it down to around 850m/s and have a better sectional density. But I doubt they would bother with all that...still, thinking about the FG42 in 6.5mm Mauser is pretty interesting.

    Post-war they'd probably want a belt fed in this cartridge and would probably upgrade the bullet design to improve aerodynamics. Not sure if there would need to be a spin off other than an upgraded rifle with inline stock design and pistol grip, plus select fire and magazine feed if it didn't already have it. No real need for an automatic rifle version, while the belt fed could be as light or lighter than OTL SAW.
     
    Last edited: Mar 14, 2019
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  8. EverKing Well-Known Member

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    A .250-3000 Garand vs. .30-06 would only be a very small difference in weight and size. The rim diameter of both cartridges is identical (0.473", 12mm) so the en-bloc clip and internal magazine would still be limited to 8 rounds given the same width and depth, but with a full clip weight a few ounces lighter than the .30-06. The .250 Savage has a maximum overall length of up to 2.515" (63.88mm) vs the .30-06 3.34" (85mm) so it would have a possible advantage in automatic fire due to a shorter cycle and it could allow for a slightly shorter receiver for the Garand as well (with slight weight savings and up to a 3/4" reduction in overall rifle length). Apart from the weight savings in ammunition and receiver, going from a 55000-60000 psi round to a 40000-45000 psi round would likely require reduced bolt and operating rod mass so the gas pressure can reliably cycle the weapon--this is where most of the weight saving would be and together with a possible shorter receiver the full rifle may be, what?, 1/2-3/4 pound lighter?

    Assuming the US Military develops the .250-3000 into a military round we have to assume a construction similar to the .30 M1 Ball used in the WWII era .30-06, with a BT-FMJ solid core round. In .258 this would probably make something like a 117-125gr bullet with a MV of around 2500-2600 fps using around 30gr of contemporary 4064 powder which puts the ME a smidge above 1700 ft-lbs, about 1100 ft-lbs less than the .30 M1 Ball. Even if they figure out how to make an 87-90gr Ball for the .258 and max the case with 35gr of 4064, it looks like we'd get a MV of 2997 and a ME of still just under 1800 ft-lbs, still over 1000 less than the .30 M1 Ball. That's a pretty significant reduction in power, although it could be argued that the .30-06 was a bit over-kill for simple anti-personnel uses anyway so maybe this is an acceptable trade-off.

    All told it would be only a minor saving in weight for the infantry who need to lug the thing and its ammo around--since the bulk of the round is similar, even though it is lighter, I don't think there would be that much of an increase in the amount each soldier would carry--with no real benefit in overall size but they may enjoy the lower recoil and better rapid fire control it would offer. In exchange they would have to accept the loss of power (which I'm assuming is "baked in" to the premise to begin with).

    Spin-offs and variants--apart from different bullets and load used by civilians--could be "neck-up" to .300 and a similar "neck-down" to .22 caliber family such as the .22-250.
     
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  9. wiking Well-Known Member

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    No need to worry about the lower energy due to the better sectional density, which means more retained energy as you go out, as well as better ballistics:
    http://abesguncave.com/sectional-density-all-important-and-almost-ignored/
    http://abesguncave.com/general-purpose-combat-cartridge-revisited/
     
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  10. Questerr Well-Known Member

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    There’s no way the Army is going to adopt a new rifle caliber and have automatic rifles firing a different caliber.

    .25-3000 would get shot down for the same reason .276 was.
     
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  11. tomo pauk Well-Known Member

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    There is no law that prevents Army to request new automatic rifles and MGs for new round.

    Not within this thread.
     
  12. wiking Well-Known Member

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    Alright, so my posts were based on that idea that that .250 caliber was 6mm rather than the reality, which is 6.5mm. So that changes a lot of what I wrote, but a 125 grain 6.5mm bullet similar to the .276 Pedersen bullet design (140-150 grain in 7mm) pushed at about 800mps would have excellent ballistic qualities compared to the M2 Ball, not least of which due to the boat tail design versus the flat base M2, but mainly from the significantly better sectional density. Plus as the Pig Board noted the 6.5mm 125 grain bullet did the most physical damage within 300 yards of all the calibers tested.
     
  13. tomo pauk Well-Known Member

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    0.25 in = 6.35 mm
     
  14. EverKing Well-Known Member

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    I think the point of the OP wasn't to examine the feasibility of the US Army adopting the .25-3000 or what kind of POD it would take for it to happen, but rather to simply examine the possible effects if it did happen. For that reason, we can assume for one reason or another the decision was already made to adopt the cartridge.

    Yup, and to your previous response to my comparison of the ME, you are absolutely correct--the 6.5mm family produces some of the best bullet designs as far as SD and BC are concerned and are known to "hit above their weight" so to speak. We have to be careful though because the .250 Savage is .258"/6.553mm as opposed to the better known 6.5mm rounds which are .264"/6.71mm caliber. So, yes, the .250 is technically 6.5mm but it is not the same 6.5mm as the 6.5 Swede, Arisaka, Carcarno, Creedmore, etc. Rather it is something in-between modern 6mm and 6.5mm calibers.

    https://www.chuckhawks.com/25caliber_cartridges.htm
     
    Last edited: Mar 14, 2019
  15. wiking Well-Known Member

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    https://en.wikipedia.org/wiki/.250-3000_Savage
    In that case if it is effectively 6.35mm as Tomo says, then it would have even better sectional density than full 6.5mm bullets at 125 grains.
     
  16. EverKing Well-Known Member

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    Here's the actual spec for the .250-3000:
    upload_2019-3-14_15-47-31.png

    Sectional Density for a 120gr .258" bullet is, coincidentally .258 vs. a 125gr .264" SD of .256. If you can build a 125gr .258 then the SD goes up to .268. Of course, the "ideal" 6.5mm is usually considered somewhere around 140gr for SD of .287.

    This brings up a very interesting possibility, even pre-war: considering the Garand action was original intended for the .276 Pederson (which is longer than the .250 Savage) and was OTL adapted for the larger .30-06 (with the same rim/base diameter as the .250 Savage), it may be feasible to create a long-neck version of the .250 Savage to allow seating longer and heavier 6.3mm bullets without reducing the powder capacity (which happens even with 117gr SBT using the normal case). This could allow us to get up to that 125-133gr or so bullet (SD between .268 and .285) with enough space for the full 35gr of powder for a MV in the 2700-2800 range, which could offer a pretty significant improvement in performance all around.
     
  17. wiking Well-Known Member

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    Or even necking down the .276 Pedersen case and using more powerful powder loads:
    [​IMG]
     
  18. tomo pauk Well-Known Member

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    Possible knonck-on effects of the late-1930s M1 Garand in .250-3000:
    - British made EM series of rifles in that calibre
    - Soviets enter the intermediate round earlier, with either the OTL 7.62x39, or perhaps 6.5x39 (6.5x40)
    - Japanese and/or Italians make self-loading rifle around their 6.5mm ammo
    - Germans make one or two self-loadind or automatic rifles in Italian 6.5mm or the 7.92 Kurz or the ALT 6.5mm Kurz
    - belt-fed BAR in the new calibre; MG3 too
    - ALT M1 Garand with folding stock and/or automatic fire option
    - CETME and FAL rifles in new calibre
    - the M14 rifle is created as automatic rifle
     
    Last edited: Mar 14, 2019
  19. EverKing Well-Known Member

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    Well, the 6.5mm cartridge they used for the Pig Board tests was, iirc, the .256 Pederson (a .25 caliber 125gr flat base bullet in a Pederson case).

    But this is getting away from the question of what kind of spin-offs and down-stream effects the adoption of the .250 Savage, specifically would have. We belabored the 6mm-7mm range of cartridges to death in the NATO doesn't adopt 7.62x51mm thread some months ago.

    I think you end up with pretty much the same rifle in both of these cases.

    Biggest hurdle in reducing the size the Garand with the .250 cartridge is that the magazine is still just as wide and deep as it is with the .30-06. I think this would dissuade its use as a crew back-up weapon a la M1 Carbine as it would still be pretty bulky. The best solution to reducing its girth in this case would be use an external box magazine that is only semi-double stack (less over-lap). This would make for a deeper magazine for the same number of rounds, but it would allow it to be thinner, and thus allow the receiver and magazine well to be likewise thinner as well.
     
  20. tomo pauk Well-Known Member

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    Hmm - yes, you're probably right.
    So the post-war version will be probably a 'Mk.2' - incorporating the lessons learned from ww2 and Korean war?

    The .250 was ~64mm AOL, the .30-06 was ~85mm. Granted, 21mm is not a big deal in a rifle 1.1m long. Some weight savings will be due to using lighter barrel, plus the lighter receiver group. Hopefully we'll arrive at about 7.5-8 lbs empty, looking at EM-2 weight.
    The ALT 'M1 Garand Carbine' will need folding stock, and probably a barrel cut by, say, 4-6 in?
     
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