WI: M1 Garand designed around .250-3000 cartridge

[Deleted member 1487]

The 7.92x41mm CTME low weight, low Drag intermediate round was developed by the Spanish (mainly by German engineers) starting in the Late 1940's To say that VLD bullets were not developed until the 19880's is a rather sweeping generalization. I have always been of the opinion that the British EM2/Rifle No9 using this .96X41 round or a derivation of it would have been a superb weapon in it's day. Get the USA to accept this round and the M14 rife might have actually made it into meaningful service!

I get what you're saying, but when we are talking about VLDs I mean not just the form factor, but also the construction of the bullet as in the link (reverse drawn jacket, open tip match). Plus they are long and heavy, not long and light like the CETME bullet.

The issue with the Cetme is how light it is. It's penetration was compromised by the light weight of the round, which is an important feature of such a round and we don't know how accurate it would have been compared to a heavy long round. Something in 5.56 or 6.35 would have been more efficient and effective with a magnum load. Though to be honest a CETME 6.35mm bullet would have been interesting.

 

[EverKing]

Unit Cost would be the big selling point

Assuming the M14 is as bad as the OTL version, would the AR-10 in 6.35mm or 5.56mm be given a chance?

A better cartridge wouldn't have helped with the Q/C and production issues that the rifles suffered from

So, are we saying that the M14 would likely still fail even if built around the more controllable 6.35 x 48mm? If that is the case, then...

I wonder if it would perform better in Vietnam due to the heavier bullet being able to penetrate jungle cover better and there being a much lighter SAW option than the OTL M60.

Yes, I believe it would. The M16 would still suffer from maintenance issues and gas-fouling in the early years until proper field care became standard and it would still benefit from an eventual conversion to a short piston instead of direct impingement but overall I think it would follow a similar path as OTL M16 but with a little more support due to the heavier hitting power.

But VLDs only came about in the 1980s

Bullets marketed specifically as VLD, yes. But the 6mm-7mm families of bullets are naturally suited to these designs as you move their weights up, most famously the higher weight 6.5mm but a high weight 6.35 would approach the same shape. In fact, a few back-of-napkin calculations and you can get a .257 caliber bullet to approach the VLD Form Factor (SD/BC) with a 120gr spitzer or better--boattail it and stretch it to say 125-130 (probably about max for the .25 cal) and you have your VLD 6.35mm sniper round. There could be trouble with OAL and headspace with a long bullet but most Snipers have custom or semi-custom rifles anyway so I think they can work around this by increasing the bore headspace and starting the rifling another few mms down the barrel (even better would be to use Gain-Twist rifling to boot).

 

[Deleted member 1487]

So, are we saying that the M14 would likely still fail even if built around the more controllable 6.35 x 48mm? If that is the case, then...

Not necessarily through the inherent design, but due to the shoddy build quality and reaction to the elements in SE Asia.

Yes, I believe it would. The M16 would still suffer from maintenance issues and gas-fouling in the early years until proper field care became standard and it would still benefit from an eventual conversion to a short piston instead of direct impingement but overall I think it would follow a similar path as OTL M16 but with a little more support due to the heavier hitting power.

Is the M16 you're talking about the AR-10 ITTL?

Bullets marketed specifically as VLD, yes. But the 6mm-7mm families of bullets are naturally suited to these designs as you move their weights up, most famously the higher weight 6.5mm but a high weight 6.35 would approach the same shape. In fact, a few back-of-napkin calculations and you can get a .257 caliber bullet to approach the VLD Form Factor (SD/BC) with a 120gr spitzer or better--boattail it and stretch it to say 125-130 (probably about max for the .25 cal) and you have your VLD 6.35mm sniper round. There could be trouble with OAL and headspace with a long bullet but most Snipers have custom or semi-custom rifles anyway so I think they can work around this by increasing the bore headspace and starting the rifling another few mms down the barrel (even better would be to use Gain-Twist rifling to boot).

When did bullets like that get adopted by the military? I know the Swedish 6.5 sniper rounds were supposed to be quite good for WW2, but have heard that they weren't exactly VLD designs. I thought most militaries relied on a mass standard sniper rifle until about the 1970s-80s.

Edit:
http://www.snipercentral.com/history-m118-ammunition/
The history of sniper ammo in Vietnam and beyond until about the 1980s sounded like it would result in some less than accurate ammo. Even nominally the ballistic coefficient dropped below VLD standards, while lacking the open tipped match design, which apparently only showed up in military match ammo in the 1980s and was barred from combat use until the 1990s. Because they are so superior in accuracy (resulted in 50% tighter groups) to traditional bullet designs now the military has converted to them .

 

[EverKing]

Is the M16 you're talking about the AR-10 ITTL?

Likely a Hybrid. ITTL, without the pressing need to re-chamber from .308 Win. / 7.62 NATO to .223 Rem. / 5.56 NATO I think it would possibly keep in the original ArmaLite model model of AR10 but I would think that the systems and ergo improvements found on the AR15 would be incorporated into this ATL AR10 design as it matures into the early-mid-1960s. After all, even IOTL most of these changes and improvements originally developed on the AR15 have made their way over to the AR10. Mechanically, they are virtually identical with the only significant difference being their cambering. Of course, that wasn't always the case; there were some pretty striking differences in their early development and production but, again, I think these modifications would still be applied to the ATL AR10 even without the existence of the AR15.

When did bullets like that get adopted by the military?

I guess I was thinking in more general terms. I can't say when, exactly, such long, high BC bullets were officially adopted by the military--if ever. I do remember reading that at least as early as the late 1960's US Army and Marine snipers were buying their own rifles and modifying them for their personal use in Vietnam with Remington 700 and Winchester 70 actions preferred. I do not think this went so far as to have them loading their own custom rounds though--that didn't start until the 80/90's iirc.

I think until experience builds most snipers would probably continue to use the .30-06 bolts or develop the .43 - .50 cal killers just as IOTL. It wouldn't be until later, after the match-grade revolution of the 90s, that they would start to experiment with 6.35mm sniper rounds, just as they have done OTL with rounds such as the 6.5 x 47 Lapua and 6.5 Creedmore.

 

[Deleted member 1487]

I guess I was thinking in more general terms. I can't say when, exactly, such long, high BC bullets were officially adopted by the military--if ever. I do remember reading that at least as early as the late 1960's US Army and Marine snipers were buying their own rifles and modifying them for their personal use in Vietnam with Remington 700 and Winchester 70 actions preferred. I do not think this went so far as to have them loading their own custom rounds though--that didn't start until the 80/90's iirc.

It seems the Vietnam era M118 nominally had a .494 BC, but the switch to regular grade primers and brass really degraded accuracy. I wonder if the older Garand rifles in 6.35mm might end up getting used as DMRs within infantry units and potentially by some snipers with the bolt action .30-06 (maybe Springfields?) used for independent long range sniping. Probably post-Vietnam we could see special sniper 6.35mms developed like they did with the 5.56 cartridge.
BTW looking at the trajectory of the .250 Savage it doesn't look like a particularly flat firing round even at 100 grains:
http://gundata.org/cartridge/21/.250-savage/

 

[EverKing]

I wonder if the older Garand rifles in 6.35mm might end up getting used as DMRs within infantry units and potentially by some snipers with the bolt action .30-06 (maybe Springfields?) used for independent long range sniping

That seems like a possible scenario, much as the US Army adopted mildly accurized M14s ITOL for their marksmen with infantry units while independent specialty snipers used bolt action rifles or customs. But I wonder what advantage there would be to them using the Garand-family for marksmen if they are using the same 6.35 as the rest of the infantry? As I understand it, the main reason the Army went with the M14 for their marksmen was the superior ballistics of the 7.62 NATO vs the 5.56. Maybe the weight increase helps as well since it reduces felt recoil and stabilized the shot, so that might be one reason.

BTW looking at the trajectory of the .250 Savage it doesn't look like a particularly flat firing round even at 100 grains

I ran some calculations using http://www.shooterscalculator.com and it looks like using a 120gr Spitzer in a .250-3000 with a BC of 0.391 and a SD of 0.260 driven by 33gr of IMR 4320 (at only an 88% load density) we get a MV of 2578. Sighting in for Maximum Point Blank Range (the range at which the trajectory is always +/-3") of 261 yards we get +2.8" @ 100 yards and 0" at 222 yards. Likewise the .308 launching a 168gr Spitzer with a BC of 0.479 and SD of 0.253 to 2708 fps by 43gr IMR 4895 gets us a MPBR of 278 yards with a +2.71" @ 100 and 0" at 236 yards.

Trajectories compared

So, yeah, the 7.62 has the advantage using these real world loadings, but I have to wonder if we'd be able to get up to our 120-125 gr 6.35 Ball and give it a Special Long Range treatment? The biggest restriction is the small case capacity. Even increasing it by using Ackly Improved and we can get the initial velocity with a 120gr to beat the 7.62mm beyond 500 yards (I played around and if we could get it up to 2600 MV it would still be supersonic out to a Mile).

EDIT: To be clear, I was only looking at the trajectories. There is almost no chance that the smaller and slower .250 would beat the .308 in energy. If we wanted to do that, we'd have to go with a .25-06 or similar.

 

[tomo pauk]

...
I ran some calculations using http://www.shooterscalculator.com and it looks like using a 120gr Spitzer in a .250-3000 with a BC of 0.391 and a SD of 0.260 driven by 33gr of IMR 4320 (at only an 88% load density) we get a MV of 2578. Sighting in for Maximum Point Blank Range (the range at which the trajectory is always +/-3") of 261 yards we get +2.8" @ 100 yards and 0" at 222 yards. Likewise the .308 launching a 168gr Spitzer with a BC of 0.479 and SD of 0.253 to 2708 fps by 43gr IMR 4895 gets us a MPBR of 278 yards with a +2.71" @ 100 and 0" at 236 yards.

Trajectories compared

Could you do the same for the 'modernized' .30-06 and 5.56?

 

[Deleted member 1487]

That seems like a possible scenario, much as the US Army adopted mildly accurized M14s ITOL for their marksmen with infantry units while independent specialty snipers used bolt action rifles or customs. But I wonder what advantage there would be to them using the Garand-family for marksmen if they are using the same 6.35 as the rest of the infantry? As I understand it, the main reason the Army went with the M14 for their marksmen was the superior ballistics of the 7.62 NATO vs the 5.56. Maybe the weight increase helps as well since it reduces felt recoil and stabilized the shot, so that might be one reason.

I'm assuming the M14 is as problematic as IOTL so scoped Garands are the stand in while the AR platform works out it's issues, plus they are on hand in storage. Apparently the Marines only adopted bolt action rifles for their snipers during Vietnam and had sniper Garands from WW2 into the 1960s.

Though the Springfield bolt action rifle in .30-06 might well have more staying power as a sniper rifle, as it was apparently IOTL the preferred one for WW2:
https://en.wikipedia.org/wiki/M1903_Springfield#Sniper_rifle

I ran some calculations using http://www.shooterscalculator.com and it looks like using a 120gr Spitzer in a .250-3000 with a BC of 0.391 and a SD of 0.260 driven by 33gr of IMR 4320 (at only an 88% load density) we get a MV of 2578. Sighting in for Maximum Point Blank Range (the range at which the trajectory is always +/-3") of 261 yards we get +2.8" @ 100 yards and 0" at 222 yards. Likewise the .308 launching a 168gr Spitzer with a BC of 0.479 and SD of 0.253 to 2708 fps by 43gr IMR 4895 gets us a MPBR of 278 yards with a +2.71" @ 100 and 0" at 236 yards.

Trajectories compared

So, yeah, the 7.62 has the advantage using these real world loadings, but I have to wonder if we'd be able to get up to our 120-125 gr 6.35 Ball and give it a Special Long Range treatment? The biggest restriction is the small case capacity. Even increasing it by using Ackly Improved and we can get the initial velocity with a 120gr to beat the 7.62mm beyond 500 yards (I played around and if we could get it up to 2600 MV it would still be supersonic out to a Mile).

If it had the quality of the OTL M118, then it would probably have the same problems until replaced in the 1990s. So you're probably looking at a DMR class cartridge with this 6.35mm round only useful out to about 500-600 yards. The .30-06 even with the flawed OTL M118 would still beat the 6.35mm except in recoil, especially out of a bolt action Remington or even Springfield. BTW the 1960s M118 was 173 grains just like the M1 ball ammo.

Here is some ballistics info about the M1 vs. M2 ball ammo:
https://m1-garand-rifle.com/30-06/

Edit:
And .308 winchester vs. .30-06:
https://www.snipercountry.com/308-vs-30-06/
Interestingly the 150 grain bullet out of the .30-06 has the flattest trajectory out to 500 yards.

EDIT: To be clear, I was only looking at the trajectories. There is almost no chance that the smaller and slower .250 would beat the .308 in energy. If we wanted to do that, we'd have to go with a .25-06 or similar.

Sure, we're only interested in ballistics for sniping. The .250 Savage in whatever configuration makes more sense within 500 yards even with the trajectory falling off beyond 400 yards compared to the 7.62 bullet due to the lower recoil and lower cost in the DMR role. Snipers doing longer range shooting given their extra training and being hand picked for their extra marksmanship would do better with the bigger, heavier round in a more accurate bolt action, but that is not only overkill for squad or platoon marksman, but less efficient for their mission.

 

[EverKing]

Could you do the same for the 'modernized' .30-06 and 5.56?

Sure can, what weight bullets are you looking at? (see my link below for some options)

BTW the 1960s M118 was 173 grains

Right, I was just using loads available from Nosler Reloading Data here. This helps take a bit of guesswork out and allows me to make some more accurate comparisons. Needless to say, Nosler doesn't have specific load data on the M118 family of Military cartridges.

DMR vs. Snipers

Completely agree with that. Squad/Platoon level DMR I would call "Marksmen" rather than full-on Snipers and for them the 6.35 in a Garand or later in an improved M21/M25 should be perfect. By Sniper, I was talking the guille-suited specialists spending three days creeping 400 yards over open ground to get their one perfect shot 1200 yards away (well, not really, but you know what I mean). For the latter, a .30-06 bolt and later .50 BMG or .416 etc. would be the weapon of choice.

 

[tomo pauk]

Sure can, what weight bullets are you looking at? (see my link below for some options)

175-180 gr for the .30-60, 70 gr for the 5.56mm.

Right, I was just using loads available from Nosler Reloading Data here. This helps take a bit of guesswork out and allows me to make some more accurate comparisons. Needless to say, Nosler doesn't have specific load data on the M118 family of Military cartridges.

Than you for the link

Completely agree with that. Squad/Platoon level DMR I would call "Marksmen" rather than full-on Snipers and for them the 6.35 in a Garand or later in an improved M21/M25 should be perfect. By Sniper, I was talking the guille-suited specialists spending three days creeping 400 yards over open ground to get their one perfect shot 1200 yards away (well, not really, but you know what I mean). For the latter, a .30-06 bolt and later .50 BMG or .416 etc. would be the weapon of choice.

There we go, for post-ww2: .50 and .30-60 (with modern ammo) when accuracy at great distance is the only thing required, plus vehicle-installed HMG/MMG. The.250 (again with modern ammo) for everything else ('carbine' instead the M4, 'normal' rifle instead of M14/M16, LMG on bipod and/or tripod).

 

[EverKing]

175-180 gr for the .30-60, 70 gr for the 5.56mm.

Here you go...

5.56 x 45mm NATO, 70gr SP using 23.5gr IMR 4895 @ 2818 fps, +2.66" @ 100 yds, 0 @ 243 yds, -3" (MPBR) @ 286 yds.
.30-06, 180gr SP using 56.5gr IMR 4350 @ 2734 fps, +2.7" @ 100 yds, 0 @ 238 yds, -3" (MPBR) @ 280 yds.

Chart and Graph Trajectory / Energy comparison to 2000 yards.

NOTE, these aren't necessarily the best/most powerful/most accurate loads, rather they are representative of the capability and I limited the powder selection to IMR powders only (thereby avoiding any modern exotics), as I did previously. Also, I used G5 drag for all of the calculations as they are representative of partially improved design (spitzer-boattail) without being full VLD designs (which would use G7 drag).

 

[Deleted member 1487]

Here you go...

5.56 x 45mm NATO, 70gr SP using 23.5gr IMR 4895 @ 2818 fps, +2.66" @ 100 yds, 0 @ 243 yds, -3" (MPBR) @ 286 yds.
.30-06, 180gr SP using 56.5gr IMR 4350 @ 2734 fps, +2.7" @ 100 yds, 0 @ 238 yds, -3" (MPBR) @ 280 yds.

Chart and Graph Trajectory / Energy comparison to 2000 yards.

NOTE, these aren't necessarily the best/most powerful/most accurate loads, rather they are representative of the capability and I limited the powder selection to IMR powders only (thereby avoiding any modern exotics), as I did previously. Also, I used G5 drag for all of the calculations as they are representative of partially improved design (spitzer-boattail) without being full VLD designs (which would use G7 drag).

I don't know what bullet you used, but the 70 grain 5.56 out of the 45mm NATO case can't possible be matching the trajectory of the .30-06 out to 1200 yards, especially with the worse coefficient for the 5.56 bullet, especially with both starting with very similar muzzle velocities.

 

[EverKing]

I don't know what bullet you used, but the 70 grain 5.56 out of the 45mm NATO case can't possible be matching the trajectory of the .30-06 out to 1200 yards, especially with the worse coefficient for the 5.56 bullet, especially with both starting with very similar muzzle velocities.

Yeah, I was questioning it as well. All I have to go off of is what the computer calculates...I have neither the time nor inclination to do it all by hand

For the 5.56 I used the only 70gr available on the Nosler site which is actually a HPBT rather than Spitzer and is call "Reduced Drag Factor." For the .30-06 I used the Partition 180gr Spitzer. You have to remember, though, that the 5.56 data is not assuming an AR-15 but rather a test rifle with a custom 20" Pac-Nor barrel so the MV (and therefore the trajectories) are most certainly improved over what we would see in an M16 or M4. This is just representative of one set of possibilities to compare the potential of the cartridges.

 

[Deleted member 1487]

Yeah, I was questioning it as well. All I have to go off of is what the computer calculates...I have neither the time nor inclination to do it all by hand

For the 5.56 I used the only 70gr available on the Nosler site which is actually a HPBT rather than Spitzer and is call "Reduced Drag Factor." For the .30-06 I used the Partition 180gr Spitzer. You have to remember, though, that the 5.56 data is not assuming an AR-15 but rather a test rifle with a custom 20" Pac-Nor barrel so the MV (and therefore the trajectories) are most certainly improved over what we would see in an M16 or M4. This is just representative of one set of possibilities to compare the potential of the cartridges.

Oh, so you're comparing a flat base, exposed lead round tip 7.62 to a match grade 5.56 boattail OTM.
Details about the 5.56 bullet:
https://www.brokenboxr.com/store/rifle-bullets/905724-nosler-224-cal-70-gr-hpbt-rdf-100box.html

Nosler’s RDF line was designed from the ground up to provide exceptionally high BCs, which create the flattest trajectory and least wind drift possible. The keys to the RDF’s outstanding performance are Nosler’s meticulously optimized compound ogive and long, drag reducing boattail, which make handloading a snap and create an incredibly sleek form factor.

And the 7.62:
https://www.nosler.com/partition-bullet
A super draggy bullet optimized to expand for hunting big game.

I don't mean to bash you for your effort, just pointing out the not exactly fair comparison if we're talking about military grade bullets for distance shooting.

 

[EverKing]

Yes, it would appear so but as I said, that was the data I have available and ready at hand. I may be able to put together some better numbers with a little more digging.

 

[Deleted member 1487]

So what are the prospects of the AR-15/5.56mm round ITTL, especially with the failure of the M14? The situation leading the USAF to adopt the AR-15 ITTL could well still happen and IOTL the tests demonstrated that even the OTL 6.35x48mm alternative to the 5.56x45 was decisively defeated in the comparison.

 

[EverKing]

So what are the prospects of the AR-15/5.56mm round ITTL, especially with the failure of the M14? The situation leading the USAF to adopt the AR-15 ITTL could well still happen and IOTL the tests demonstrated that even the OTL 6.35x48mm alternative to the 5.56x45 was decisively defeated in the comparison.

Hmm...The OTL 6.35x48FA59 (.25Win) tested against the 5.56x45 was a high velocity (3300 fps), short, flat-based 70gr bullet. Also tested was a 6.35x48FA-T125 (25WinDuplex) with was the same, more or less, but with two 53gr bullets at 2600fps and 2460fps (respectively) stacked in the case. This is quite different from our ATL 6.35x48 NATO which fires a longer, higher BC and SD, 120gr +/- bullet at something in the 2600 fps range (I don't know that we've settled on the exact numbers for this round but the .25-08 wildcat / .25 Souper can push a 120gr to 2800fps so I think 2600 out of our 6.25x48 is acceptable) so I am not sure how the comparison would go. Maybe, to maintain a standard caliber, the powers that be would push for the 6.35x48 HV (the OTL 6.35x48, more or less) for carbine and sentry duty as it could still be loaded and fired from the standard battle rifle, thereby avoiding potential problems with green draftees. If so, then we could still see the M16, but in 6.35 instead of 5.56.

 

[Deleted member 1487]

Hmm...The OTL 6.35x48FA59 (.25Win) tested against the 5.56x45 was a high velocity (3300 fps), short, flat-based 70gr bullet. Also tested was a 6.35x48FA-T125 (25WinDuplex) with was the same, more or less, but with two 53gr bullets at 2600fps and 2460fps (respectively) stacked in the case. This is quite different from our ATL 6.35x48 NATO which fires a longer, higher BC and SD, 120gr +/- bullet at something in the 2600 fps range (I don't know that we've settled on the exact numbers for this round but the .25-08 wildcat / .25 Souper can push a 120gr to 2800fps so I think 2600 out of our 6.25x48 is acceptable) so I am not sure how the comparison would go. Maybe, to maintain a standard caliber, the powers that be would push for the 6.35x48 HV (the OTL 6.35x48, more or less) for carbine and sentry duty as it could still be loaded and fired from the standard battle rifle, thereby avoiding potential problems with green draftees. If so, then we could still see the M16, but in 6.35 instead of 5.56.

I'm wondering if the 6.35mm might not end up getting replaced by the 6x45mm SAW.

 

[EverKing]

I'm wondering if the 6.35mm might not end up getting replaced by the 6x45mm SAW.

The 6x45 SAW was a fine cartridge but the differences between it and our ATL 6.35x48mm aren't sufficient to justify replacing the battle tested and proven round that NATO has used since its inception and the US has used since WWII. The 6mm SAW tested used a 105gr bullet at a shade over 2500 fps and it would have had worse overall performance than our 120gr 6.35mm (even if we downgrade it to 2500 fps). If they want a hole-puncher, then make an upgraded 6.35mm with a lighter and faster bullet rather than deal with the headache of testing and accepting an entirely new chambering. Alternatively, if they are looking for something more controllable in a shoulder fired full-auto, go for a lighter bullet with slower powder to reduce recoil.

It just seems like @tomo pauk was right with a .250-3000 derived cartridge and we hit the sweet spot--hard to justify going bigger in an infantry rifle and hard to justify going smaller.

 

[Deleted member 1487]

The 6x45 SAW was a fine cartridge but the differences between it and our ATL 6.35x48mm aren't sufficient to justify replacing the battle tested and proven round that NATO has used since its inception and the US has used since WWII. The 6mm SAW tested used a 105gr bullet at a shade over 2500 fps and it would have had worse overall performance than our 120gr 6.35mm (even if we downgrade it to 2500 fps). If they want a hole-puncher, then make an upgraded 6.35mm with a lighter and faster bullet rather than deal with the headache of testing and accepting an entirely new chambering. Alternatively, if they are looking for something more controllable in a shoulder fired full-auto, go for a lighter bullet with slower powder to reduce recoil.

It just seems like @tomo pauk was right with a .250-3000 derived cartridge and we hit the sweet spot--hard to justify going bigger in an infantry rifle and hard to justify going smaller.

The difference in performance is made up in the SAW being significantly lighter than the 6.35 and being to replace it in the rifle role, as well as LMG and many sniper applications, while being lighter recoil and still good range and AP ability.

What qualifies as the 'sweet spot'? Arguably a hotter 6mm round would have all the advantages of the 6.35 and more. Arguably the 6mm Lee Navy was the sweet spot if you'll check the quoting I did about the 6mm optimum on the first page.