[Ultra Tech] Increased Firearm Power with TL

[Fred Brackin]

Originally Posted by Anthony

It really is in this case. The reason the SIG Fury has such a huge chamber pressure is because the army wanted full length rifle performance from a 16" barrel.

It really is not the case as a general principle. If you could raise muzzle velocity significantly with longer barrels no one would have retreated from the 32 inch barrels smokeless powder rifles started with. The utility of adding propellant and barrel length falls off rapidly.

[Ulzgoroth]

Originally Posted by Fred Brackin

It really is not the case as a general principle. If you could raise muzzle velocity significantly with longer barrels no one would have retreated from the 32 inch barrels smokeless powder rifles started with. The utility of adding propellant and barrel length falls off rapidly.

That's a fairly radical claim, considering the drift to assault carbines which knowingly sacrificed muzzle velocity for handiness...


Making it work without spiking the peak chamber pressure also requires you have very sophisticated control of the propellant burn profile. I'm not sure that was applicable at the time, but it probably is looking forward from the present.

[Varyon]

Originally Posted by Anthony

Nah, my point was just "higher chamber pressure doesn't get you anything you can't get from a longer barrel and more propellant".

That seems like a case of needlessly splitting hairs. Correct me if I'm wrong, but on a very simplistic level, it seems like more (powerful) propellant gets you better performance but requires a longer barrel, while higher chamber pressure for a given quantity of propellant can serve in place of a longer barrel. +P ammunition - what we're looking at here - uses both more (powerful) propellant and higher chamber pressure to get increased performance. In light of the SIG Fury, I was curious as to what sort of ramping up might be doable as TL increases (probably thinking of the Fury as more in line with TL 9 than TL 8, albeit possibly just something straddling the difference). Although maybe part of the necessary changes to get better performance is a heavier (and thus probably longer, given constant caliber) bullet, which may not feasibly fit in a typical cartridge?

Originally Posted by Anthony

It's worth noting that rifle muzzle velocity has not gone up meaningfully in a hundred years -- the SIG Fury has about 5% higher muzzle velocity than the M1903 Springfield, and lower than a Vietnam era M-16 (55 grain .223 is, as far as I can tell, the fastest ammunition ever used as a primary military rifle).

There may be issues with exceeding certain speed limits, in which case you'd increase kinetic energy by using a heavier bullet instead. But it may also simply be the case that there hasn't been a sufficient need for an increased velocity to justify a new weapon system capable of producing it. But this thread isn't concerning itself only with military munitions (or more specifically military munitions in something like the modern Earth milieu), and there are certainly civilian rounds on the market today that have velocities far in excess of the XM193 (that 55 grain bullet that was thrown at around 3,250 fps); for example, I think the .220 Swift is regarded as the fastest bullet on the market, and is typically around 4,000 fps (a 23% increase compared to the XM193, 33% compared to the SIG Fury), while there are apparently 4,250 fps (31% / 42%) versions available, and apparently handloaders can get it up to 4,500 fps (38% / 50%).

[Anthony]

Originally Posted by Fred Brackin

It really is not the case as a general principle. If you could raise muzzle velocity significantly with longer barrels no one would have retreated from the 32 inch barrels smokeless powder rifles started with. The utility of adding propellant and barrel length falls off rapidly.

The SIG Fury did not raise muzzle velocity significantly. Raising muzzle velocity with +P ammunition and the like is really a pistols-only phenomenon.

[Fred Brackin]

Originally Posted by Anthony

The SIG Fury did not raise muzzle velocity significantly. Raising muzzle velocity with +P ammunition and the like is really a pistols-only phenomenon.

I question it as a general principle and you respond with a single case? It's even a case where they raise p.s.i. to avoid _losing_ muzzle velocity. It does not support a general principle where you can increase muzzle velocity with longer barrels and more propellant without any mention of limits.

[Fred Brackin]

Originally Posted by Varyon

T


There may be issues with exceeding certain speed limits,).

Yes, the bullets break into little pieces when they hit things. That's why it's usually only done with (deliberately)frangible bullets and varmint rifles where extreme break up is desirable.

[Anthony]

Originally Posted by Fred Brackin

I question it as a general principle and you respond with a single case? It's even a case where they raise p.s.i. to avoid _losing_ muzzle velocity. It does not support a general principle where you can increase muzzle velocity with longer barrels and more propellant without any mention of limits.

I never said that. My point was the reverse: increasing chamber pressure is subject to exactly the same limits.

[Fred Brackin]

Originally Posted by Anthony

I never said that. My point was the reverse: increasing chamber pressure is subject to exactly the same limits.

<cut and paste you>
"Nah, my point was just "higher chamber pressure doesn't get you anything you can't get from a longer barrel and more propellant"."

That looks very much to me like a statement of a general principle that you can improve performance with longer barrels and more propellant.

[Anthony]

Originally Posted by Fred Brackin

<cut and paste you>
"Nah, my point was just "higher chamber pressure doesn't get you anything you can't get from a longer barrel and more propellant"."

That looks very much to me like a statement of a general principle that you can improve performance with longer barrels and more propellant.

You can. There's limits to it, but the same limits apply to boosting chamber pressure. If you want revolutionary changes you need new propellants. Frankly, we may have hit the limits of solid shelf-stable monopropellants (note that GURPS has REF 4 explosives at TL 9 and REF 6 at 10, which indicates something new, but there's no evidence of anything that dramatic actually occurring).

[Ulzgoroth]

Originally Posted by Varyon

That seems like a case of needlessly splitting hairs. Correct me if I'm wrong, but on a very simplistic level, it seems like more (powerful) propellant gets you better performance but requires a longer barrel, while higher chamber pressure for a given quantity of propellant can serve in place of a longer barrel.

This is a kind of odd framing, since adding more propellant, absent carefully changing the nature of that propellant, will extremely directly translate into increased chamber pressure. What you're calling 'more propellant' here seems to be a prolonged burning curve...which does require more propellant, yes, but it doesn't stop there!

All else being equal higher peak pressure does seem it should let you do more in less space though. Assuming of course that your chamber doesn't explode.

Originally Posted by Anthony

You can. There's limits to it, but the same limits apply to boosting chamber pressure. If you want revolutionary changes you need new propellants.

Wait, what exactly would new propellants change about the problem? Going into the future, as per the seeming topic of the thread, not going forwards from black powder.