What should our standard military cartridge be?

[yuppiejr]

I believe Jordan and Saudi Arabia have begun to equip special forces and royal guard units with US manufactured AR pattern rifles and belt fed MGs in 6.8 SPC.


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[Randygmn]

For me personally, I like the 300blk and its versatility, although it's not strong out past 300 yards. For a civilian, it can't be beat, IMO. It can fire supers and subs, with or without a can. It's got more on target energy than the 556 or 762x39. Wide variance of bullet weights from 110 to 220. Only needs a new barrel for conversion. Again, not suitable for engaging targets past 3 or 400 yards.

[MJY65]

For me personally, I like the 300blk and its versatility, although it's not strong out past 300 yards.

It's certainly got its merits in CQB, but I can't see the military going back to 30-30 like ballistics.

[photogpat]

I had some help running the ballistics on my 6.8 out of a 14.5" barrel -- 90gr Speer Bonded Soft Point, 2710 fps muzzle and .210 BC.

Range Drop Drop Windage Windage Velocity Mach Energy
(yd) (in) (mil) (in) (mil) (ft/s) (none) (ft•lbs)
0 -1.5 *** 0.0 *** 2750.0 2.463 1511.0
25 -0.6 -0.7 0.0 0.0 2643.7 2.368 1396.5
50 -0.1 -0.0 0.0 0.0 2539.9 2.275 1289.0
75 0.1 0.1 0.0 0.0 2438.5 2.184 1188.1
100 -0.0 -0.0 0.0 0.0 2339.4 2.095 1093.5
125 -0.5 -0.1 0.0 0.0 2242.5 2.009 1004.8
150 -1.5 -0.3 0.0 0.0 2147.9 1.924 921.8
175 -3.0 -0.5 0.0 0.0 2055.5 1.841 844.2
200 -4.9 -0.7 0.0 0.0 1965.6 1.761 771.9
225 -7.4 -0.9 0.0 0.0 1878.0 1.682 704.7
250 -10.6 -1.2 0.0 0.0 1793.1 1.606 642.4
275 -14.4 -1.5 0.0 0.0 1710.9 1.532 584.9
300 -19.0 -1.8 0.0 0.0 1631.8 1.462 532.0
325 -24.3 -2.1 0.0 0.0 1555.8 1.394 483.6
350 -30.6 -2.4 0.0 0.0 1483.3 1.329 439.6
375 -37.9 -2.8 0.0 0.0 1414.6 1.267 399.8
400 -46.2 -3.2 0.0 0.0 1350.0 1.209 364.1
425 -55.7 -3.6 0.0 0.0 1289.9 1.155 332.4
450 -66.6 -4.1 0.0 0.0 1234.6 1.106 304.6
475 -78.9 -4.6 0.0 0.0 1184.6 1.061 280.4
500 -92.7 -5.1 0.0 0.0 1140.1 1.021 259.7
Drops subsonic at 525yds.

[Ghost]

Easy, 6.5 Grendel

Nope, 6.8 SPC, that is what it was designed for.

6.8 was designed for it but the Grendel still has some advantages with negligible shortcomings.

[20mm]

.500 Phantom

[Bearcatrp]

If you have never carried 7 mags full before, then you won't understand the reason for a light round for the military. I carried this for 7 months during Desert Storm and could not even think of carrying a heavier load, along with the rest of the gear I had to lug around (ruck sack, body armer, etc). I've read up on the latest study when the Army was looking into replacing the 5.56. With the latest technology, I think a better bullet for the 5.56 would work out and not cost a ton replacing all the M16's. For special forces and such, yes, get a better round which I think they do already.

[MJY65]

I think a better bullet for the 5.56 would work out and not cost a ton replacing all the M16's. For special forces and such, yes, get a better round which I think they do already.

That's exactly what they should do. A slightly heavier bonded soft point makes the 5.56 a much better round. As to the "rules", they are ridiculous. Somehow, it's unfair and illegal to shoot someone with an expanding bullet, but perfectly fine to hit him with a Hellfire missile from a drone? Pure silliness.

[yuppiejr]

For me personally, I like the 300blk and its versatility, although it's not strong out past 300 yards. For a civilian, it can't be beat, IMO. It can fire supers and subs, with or without a can. It's got more on target energy than the 556 or 762x39. Wide variance of bullet weights from 110 to 220. Only needs a new barrel for conversion. Again, not suitable for engaging targets past 3 or 400 yards.

The .300 blk is inferior to 6.8 SPC or 6.5 Grendel in a standard milspec size AR15/M16 lower receiver based firearm with more than a 10" barrel in almost every way out to 300-400 yards... at which point you are probably better off with a full size battle rifle platform if that's a standard engagement distance. The use of common AR15/M16 magazines and bolts along with the use of common .223/5.56 NATO brass and .30 caliber projectiles make .300 blk interesting to tinkerers-reloaders, or folks who want to shoot suppressed under 100 yards. If I was looking for an alt AR15 chambering using standard AR bolts + mags and .223/5.56 NATO brass that significantly improved terminal performance over .223/5.56 NATO or .300 blk I'd be all over the .277 Wolverine wildcat that Mad Dog Weapon Systems is developing.

I'd also say that M855 + an M4 is a fairly terrible combination if terminal performance on soft targets (Taliban/ISIS fighters, etc..) is your primary goal and not punching through lightly armored Soviet troop carriers at short range. The M4/M855 combo is the baseline that most of the alternative caliber AR15/M4 marketing geeks compare against even though the MK262 or MK318 in a standard M4 carbine is probably a fairer baseline for comparison to the .300 blk/6.8 SPC/6.5 Grendel options on the market, at which point the performance gains of the alt-calibers is trimmed back considerably making it hard to justify the logistics of a larger scale adoption.

[yuppiejr]

Easy, 6.5 Grendel

Nope, 6.8 SPC, that is what it was designed for.

6.8 was designed for it but the Grendel still has some advantages with negligible shortcomings.

7.62x39 and 6.5 Grendel AR15's share the same shortcoming in bolt & extractor construction, in order to accommodate the large case rim the bolt lugs + extractor groove are relieved significantly enough that premature failure of the lugs is not uncommon particularly if you exceed the AArms recommended 50k PSI max chamber pressure figure with regularity. You've also got significantly fewer commercial ammo options including only one major commercial ammunition manufacturer putting product out in quantity (Hornady) unless you include the unicorn that is the 4 MOA Wolf steel cased stuff that AArms manages to import once in a blue moon. Ammoseek shows about 85 in-stock ammo purchasing options (almost all Hornady at around $1 a pop) in 6.5 Grendel while 6.8 SPC and .300 blk have 350+, each including low priced plinking ammo that tickles $.050-$.60 per round.

[Grayskies]

I think a better bullet for the 5.56 would work out and not cost a ton replacing all the M16's. For special forces and such, yes, get a better round which I think they do already.

gggb
That's exactly what they should do. A slightly heavier bonded soft point makes the 5.56 a much better round. As to the "rules", they are ridiculous. Somehow, it's unfair and illegal to shoot someone with an expanding bullet, but perfectly fine to hit him with a Hellfire missile from a drone? Pure silliness.

I like some of the rules, but when we lose people over trival stuff... Well some rules need to change. Actually what good are the rules if we are the only one playing by them?

[Ghost]

7.62x39 and 6.5 Grendel AR15's share the same shortcoming in bolt & extractor construction, in order to accommodate the large case rim the bolt lugs + extractor groove are relieved significantly enough that premature failure of the lugs is not uncommon particularly if you exceed the AArms recommended 50k PSI max chamber pressure figure with regularity. You've also got significantly fewer commercial ammo options including only one major commercial ammunition manufacturer putting product out in quantity (Hornady) unless you include the unicorn that is the 4 MOA Wolf steel cased stuff that AArms manages to import once in a blue moon. Ammoseek shows about 85 in-stock ammo purchasing options (almost all Hornady at around $1 a pop) in 6.5 Grendel while 6.8 SPC and .300 blk have 350+, each including low priced plinking ammo that tickles $.050-$.60 per round.

Most of the bolt issues were from not using the actual Colt bolt designs for the 7.62x39 which AA used for the Grendel. AA kept the Grendel under their control too long so the 6.8 and 300BLK outpaced it with industry support, it's starting to come around but it's slow.

Reality is that if the military picked any of the existing designs as is I'd be surprised, they'd probably try to go to an LSAT design to save weight. The infrastructure to switch would be monumental but if they used an entirely new platform they could give all the old ones to the police along with some MRAPs.

[Bearcatrp]

perfectly fine to hit him with a Hellfire missile from a drone? Pure silliness.

As long as it kills them, who cares what is used.

[lizard55033]

There is nothing wrong with the 5.56/.223 for the military; great round!

What they need to do is go with more of a jacketed hollow point vs the current ball ammo. The only issue is with the Geneva Convention (I believe) stating that you can't use such a round.

[MJY65]

perfectly fine to hit him with a Hellfire missile from a drone? Pure silliness.

As long as it kills them, who cares what is used.

I agree. Thus my assertion that the FMJ requirement is ridiculous.