Is there any benefit to short barreled 7.62 nato?

[PathfilmsNZ]

What velocity are you getting from 11" .308 barrels with what projectiles?

Nothing yet but ~*quickload*~, that most reliable of sources, tells me that a 12.5" .308 ought to get around 2450 with a 150gr bullet loaded to max SAAMI pressure which shits all over a .300 AAC

[PathfilmsNZ]

Nothing yet but ~*quickload*~, that most reliable of sources, tells me that a 12.5" .308 ought to get around 2450 with a 150gr bullet loaded to max SAAMI pressure which shits all over a .300 AAC

Obviously it depends what you want but for a compact semi-auto with the ability to reach a lot further I'd personally take a short-ass suppressed .308 over an .300 AAC given that it'd be getting about 500fps more with the same weight bullet. Purely for my personal use, I have no pretensions of military use.

[Heavy Metal]

Gotcha. When you say projectile performance (why does that phrase make me think of Smiling Bob?) do you mean velocity? If so, the ratios do affect velocity.

To clarify for those who don't understand, a magnum capacity case launching a 30 caliber bullet will need a longer barrel to achieve full velocity that the same case launching a 45 caliber bullet. That's because the volume of the 45 caliber bore is larger and while the case volume is identical in both cases, the case volume in ratio to the diameter of the 45 caliber bullet is less. While the powder expands when ignited, it rate of expansion is finite.

The 50 BMG is simply the 30-06 scaled up in all dimensions until the bullet is 50 caliber. The 5.56 is close to being the 30-06 simply scaled down

I believe the .222 Remmington, the precursor to the .223/556 being essentially a slightly stretched .222, is actually a the same scale dimensions as a 30-06 by design.

[SPQR476]

I get 2450-2475fps or so out of my 12.7" g3k clone with Radway and SA ball, 147 and 145 gr, respectively. It works pretty well out to 500, and then the difference between it and a more normal barrel length starts to run away, but up to that point, it's not that bad of a difference to wrap your brain around. You're still shooting heavier bullets with good bc's compared to 7.62x39 or .300blk. It's a world better than 7.62x39 at range, for sure.

Whether the extra weight and lower capacity is worth it is another matter. I love the doggone thing, I'll say that much. As an urban DMR or as a lighter variant among a unit full of heavier .308 platforms, it shines. It DOES NOT get everything possible out of the .308-- I'm not arguing that it does.

Flash isn't bad at all with a vortex. Blast isn't bad, either.

The 8.5" guns referred to earlier, not really an official HK variant, but seen offered as 51s with various prefixes or as the PTR PDW (Hk numbering convention- 5x=8.5" bbl (a la hk 53) and x1=.308, thus 51=8.5" .307.) is a little too much of a good thing. 2200-2250fps with ball. Still theoretically better performance at range than a 16" ak due to bc, but it's kind of like a flash bang with every trigger press, and you're not even getting close to a full twist in the barrel. I've never shot one past 25 yards, though, so I can't comment on actual performance beyond that. I've only got a few mags through these, and although sexy to handle and look at...HK stopped at 12.7." with the G3k for a reason.

[Javelin]

Powder burning outside the barrel has zero affect on recoil. Powder exiting under high velocity from the muzzle has a large affect on recoil. It adds to the thrust, same as the gasses exiting the nozzle of a rocket engine.

The difference in velocity between a 300 BLK or the 7.62x39 and the 7.62x51 isn't but about 100 fps when the barrels are very short. The 308 would be using twice the powder for very little gain. From SBR length barrels, the 300 BLK would be doing about the same job more effeciently using lighter, smaller ammo and with less recoil due to using only half the powder.

Suwannee Tim's ratios are dead on. It's all about the case volume/bullet diameter/barrel length ratio and why a small capacity case is better for pistols and a large capacity case works better in longer barrels. It's also why the 300 BLK will operate a carbine length gas system reliably but not a middy

My 8" 300Blk does fine but I have never put it through a chrono. Hits steel targets like a sledge hammer compared to 5.56 though

[wyld3man]

The only experience I have with a SBR 7.62 is the MK17 with the short barrel installed (I think it is 13.5"). I used it for a couple months with the 16" installed and it was fairly accurate out to 600m or so (with M118) I then decided to put the shorty barrel on it because it was easier handle while getting in and out of vehicles and in other tight spots. I had no problem hitting targets out to 500m. I now only use the shorty because most situations which I need to engage something will be under 500m.
I think the major benefit of a 7.62 SBR would be compactness/ easy to maneuver and some good knock down power. I have even been tossing around the idea of submitting the papers and building a 7.62 SBR.

[Dano5326]

I see little use to it... outside of specialized/ammo applications. Massively inefficient and bulky for the ballistics one gets.

for an added 2.5-3" of barrel (13" HK417, 13.5" SCAR-H, 13.5" LMT MWS) one gets a ALOT more capability.

For the short game a 5.56 is far; lighter, quieter, faster to run.

[redhooker]

The numbers are from work and government testing.

...and they mirror my results with a 16 and 20 inch MWS within about 10fps or so of my AV, chrono'd here in humid FL over 200 rds from different year LC lots. I can actually load to get over 2600fps with the 16" with no pressure signs, but my rifle shoots most accurately around 2480.

[uncommon commoner]

For the short game a 5.56 is far; lighter, quieter, faster to run.

Yes, this is true. But, if the short game involves automobiles, walls, doors, glass, trees, cinder blocks, etc., I would still prefer a 10 inch 7.63/308 over a 16 inch 5.56/223.

[gun71530]

I get 2450-2475fps or so out of my 12.7" g3k clone with Radway and SA ball, 147 and 145 gr, respectively. It works pretty well out to 500, and then the difference between it and a more normal barrel length starts to run away, but up to that point, it's not that bad of a difference to wrap your brain around. You're still shooting heavier bullets with good bc's compared to 7.62x39 or .300blk. It's a world better than 7.62x39 at range, for sure.

Whether the extra weight and lower capacity is worth it is another matter. I love the doggone thing, I'll say that much. As an urban DMR or as a lighter variant among a unit full of heavier .308 platforms, it shines. It DOES NOT get everything possible out of the .308-- I'm not arguing that it does.

Flash isn't bad at all with a vortex. Blast isn't bad, either.

The 8.5" guns referred to earlier, not really an official HK variant, but seen offered as 51s with various prefixes or as the PTR PDW (Hk numbering convention- 5x=8.5" bbl (a la hk 53) and x1=.308, thus 51=8.5" .307.) is a little too much of a good thing. 2200-2250fps with ball. Still theoretically better performance at range than a 16" ak due to bc, but it's kind of like a flash bang with every trigger press, and you're not even getting close to a full twist in the barrel. I've never shot one past 25 yards, though, so I can't comment on actual performance beyond that. I've only got a few mags through these, and although sexy to handle and look at...HK stopped at 12.7." with the G3k for a reason.

Any chance of a pic of your G3k? I have a serious love affair with that gun.

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