Assault Rifle article revised

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Tony Williams

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I have revamped my web article Assault Rifles and their Ammunition: History and Prospects to include more detail about early developments and bring the present situation up to date. URL is http://www.quarry.nildram.co.uk/Assault.htm

Here's a pic from it showing current and possible future rifle/MG ammunition.

P1070008.jpg
 
By the way, does anyone know why the guys who designed the 6.8 SPC didn't shorten the neck a little and make the bullet a little bigger (maybe, 125 grains or so?) That seems to me to be a much better cartridge, not really sacrificing anything, but giving you a nice boost to range and barrier penetration.
 
Shortening the neck wouldn't help. The longer bullet would still protrude further into the case, reducing the quantity of propellant you could use.
 
Shortening the neck wouldn't help. The longer bullet would still protrude further into the case, reducing the quantity of propellant you could use.
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Yeah, but not by a whole lot, and you could streamline your bullet better (seeing the sharp step on the SPC's bullet just makes me cringe). Your velocity would go down a bit, bit it'd still be in the same range, which is the range you want to be in.
 
Yeah, but not by a whole lot, and you could streamline your bullet better (seeing the sharp step on the SPC's bullet just makes me cringe). Your velocity would go down a bit, bit it'd still be in the same range, which is the range you want to be in.
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:scrutiny:

And you have both the testing equipment and software to prove this? They made it as-is for a reason, more than likely....
 
And you have both the testing equipment and software to prove this? They made it as-is for a reason, more than likely....
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Of course I don't. I'm just using logic based on the observance of other cartridges. My estimate is that the speed would go down to, oh, 2550 f/s give or take, which is still in Tony's "ideal" range.
 
Good stuff, Tony - KUTGW*! I'm so happy to seen when the phrase 'assault rifle' is used *correctly* on this and other websites.

(*keep up the good work)
 
Tony, I've been thinking about something. What if you took the 7.62x39mm with the pressure upped to 55000 (as opposed to the 45000 that it has normally) and then used the advanced powders as used in the 6.8 SPC cartridge and loaded it with a 130-140 grain explosive bullet based around the same technology as the Raufoss (without the armor piercing part)? It seems to me you'd get something on the order of 2400-2500 f/s and a significantly better BC, so your range would go up a decent amount (it seems to me that the 'x39 is right at the edge of optimal combat rifle range, anyway), and with an explosive bullet you should get really good terminal effectiveness (and possible better anti-material effectiveness as well).
It's just an idea I've been playing with.
 
There's the slight flaw that explosive bullets for anti-personnel use are banned by international agreement, and have been for the last 140 years.
 
There's the slight flaw that explosive bullets for anti-personnel use are banned by international agreement, and have been for the last 140 years.
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Yeah, okay, I figured something like that'd come up. Like no one's ever been shot by a cannon or Raufoss round, or hit by a grenade... :rolleyes:
Other than that, do you think that about sounds right?
Even if I don't go with the exploding bullet (or found a way to make people think it was merely a "dynamic" action, or actually found a way to make it a dynamic action), do you think that the speed and weight sound roughly right?
 
the advanced powders as used in the 6.8 SPC
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You mean.... good ol' IMR 4198? Looks like charging it up to 55kpsi only yields about 1800 FPS with a 140 gr bullet. And a destroyed gun, mind you.
 
You mean.... good ol' IMR 4198? Looks like charging it up to 55kpsi only yields about 1800 FPS with a 140 gr bullet. And a destroyed gun, mind you.
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That's what they use? Isn't that a fast-burning powder? I was under the impression they used a slower-burning fuel to make up for the lack of case capacity (where otherwise they might have to have a base similar to the Grendel's). And 140 Gr. was the top of the spectrum (also, what barrel length are you talking about?), I was more interested in the 132-136 grain range. Though I don't imagine that that get's me the extra 700 f/s.
And yeah, I'm aware that 7.62x39 guns aren't proofed for that, I was talking about an entirely different platform. SAAMI "only" proofs to 125%. Of course, we may want to see if we can find a way to ".357 Magnify" it, that is, make the rifle capable of taking 'x39, but not having old 'x39 guns take the new high-pressure round. I guess a longer neck would do it, but man it'd be an ugly-ass cartridge.
 
Tony, I'm curious about the 5.2 Mondragon round. I was under the impression that it's unusual shape had to do with an internal seal that broke under the initial stress of firing to keep peak pressures down.
 
And here's the source on that:

http://www.cruffler.com/historic-february01.html

"The resultant round, the 5.2x68mm Rubin, may well have been too much for the Mondragon. Indeed, it was almost too much for itself! To handle the extreme pressures generated when it was fired, the 5.2x68mm's bullet was surrounded by a detachable collar that moved forward within the case as the powder gases expanded so as to increase the size of the
combustion chamber."
 
I was under the impression they used a slower-burning fuel to make up for the lack of case capacity (where otherwise they might have to have a base similar to the Grendel's).
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My understanding is that slow-burning powder is usually bulkier than fast-burning, but it's a long time since I was involved in reloading so I could be wrong.

My understanding of the Mondragon cartridge design is that the internal piston was intended to increase the initial bullet velocity. The chamber pressure acting on the much wider piston can shove it forwards with considerably more force than if it's only pressing on the narrow bullet base. When the piston is stopped at the end of the case, the bullet is broken free of the piston to be pushed down the barrel.

This should work theoretically, but is obviously more trouble than it's worth as no-one's bothered with it since.
 
My understanding of the Mondragon cartridge design is that the internal piston was intended to increase the initial bullet velocity. The chamber pressure acting on the much wider piston can shove it forwards with considerably more force than if it's only pressing on the narrow bullet base. When the piston is stopped at the end of the case, the bullet is broken free of the piston to be pushed down the barrel.
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Sort of like a sabot then; increase the amount of volume swept by pressure. Pressure is force over area, times distance cubed is force times distance, i.e. work.

Does anyone have access to Mondragon's design notes? I wonder what he was thinking when he did that.
 
Another thing I've been thinking about is a 102-grain .224" projectile at 2600-2700 f/s. Can i get any input from those that study such things? (Yes, I know 102 grains is ridiculously heavy for a .224" projectile, that's partly the point. I want a ridiculous BC to retain energy, and I want a heavy weight to be good at barrier penetration). I think the that loading would be just about as good as the 6.5 GunTech, and a good deal lighter.
 
Some good info on that in the NDIA archives. Apparently the propellant is the same as in the HK G11.
 
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