Most modern tank use smoothbore guns, which is a reversal of a trend going back nearly 200 years. Why cannot smoothbores be used for handguns, machine gunsm artillery pieces etc. The stability issue is resolved using fins and while it might be difficult for personal firearms, why not for crew served weapons?
The 120mm RB gun on the Abrams maybe but all other MBTs have rifled barrels AFAIK (Challenger, Le Clerc, T-95.)
The difference between tanks and other crew-served weapons is that tanks firing anti-tank munitions are like small arms - they do kinetic rather than explosive damage. A saboted AT round is effective because it’s very very fast, so fast that rifling would just slow it down. Smaller calibers can’t achieve those speeds, and larger calibers, like artillery, don’t need them.
T95 is cancelled and it was supposed to have a smoothbore and the Leclerc has one as well as does the Merkava and Leopard. Only the Challenger and the Indian Arjun have rifled guns.
They can be used for non-tank guns. They’re common in shotguns and used to be the mainstay in muskets.
The main reasons for artillery and small arms not using APFSDS rounds that I can see:
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Adding sabot and fins increases cost and complexity. Not a big deal with a 4-8 million dollar tank shooting at other tanks during the highest intensity part of the war.
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It reduces the diameter of the projectile. APFSDS rounds are chiefly designed to penetrate the very best armor, not make a big holes in easily penetrated squishy meat or carry a large explosive payload. Reducing projectile diameter is not that big a deal with APFSDS rounds and might be desirable even if rifling were used instead of fins.
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To really make use of a smoothbore barrel’s higher velocity potential, you need a lot of propellant and an awfully long barrel. All that propellant tends to make the barrel wear out quickly, some Abrams rounds will wear out the barrel in about 50 shots ( Rheinmetall Rh-120 - Wikipedia) . Replacing the barrel isn’t a big problem when a good portion of those shots have destroyed tanks and you need to rearm, refuel and rest anyway. But it’s unacceptable with small arms.
The high velocity wouldn’t be all that much use for artillery since kinetic energy* doesn’t matter to artillery; range is about ballistic coefficient and momentum* and effect is about payload. Also, since arty rounds need to travel much further than tank rounds or small arms projectiles, they’re exposed to air resistance for a lot longer and air resistance goes up at the square of velocity.
- Both momentum and kinetic energy are influenced by velocity but it’s more much important for kinetic energy.
These folks are working on it. It’s a laser guided dart-like round fired from a smooth bore handgun sized weapon. It is guided by microprocessor controlled fins. They claim that their prototypes prove not only that it works but that it can be done for a reasonable cost.
They are still working out some engineering issues (in other words it doesn’t work very well, if at all) and they are looking for a private sector partner (they need money). But it’s interesting, IMHO.
Don’t let Gene Simmons hear about this!
Challenger 2 is being switched to a smoothbore gun for better compatibility with the Abrams and Leopard/2 (and because the British production lines for rifled rounds were shut down years ago). The Leclerc has always had a smoothbore gun.
Actually from what I gather, the thing is that the spin from a rifled barrel messes up the accuracy of discarding sabot rounds versus fin-stabilized ones.
Since most small arms want to make a wide hole versus a deep one (more or less; penetration is still important), having a discarding sabot round doesn’t make sense, and regular old rifled barrels and full-diameter rounds are best.
Mortars are typically smoothbore and fin-stabilized, so it is used for some artillery.
Pistols, yes, but military rifles are all about making small holes.
It is my understanding as well that there is a limit to the muzzle velocity that can be attained by a rifled barrel before the rounds will strip the rifling.
APFSDS: Armor Piercing, Fin-Stabilized, Discarding Sabot.
Old artillery guy here. Had to look that one up.
I’m speculating here, but wouldn’t a spinning sabot screw up the projectile’s trajectory when it came time to seperate from the projectile?
I was also under the impression that anti-tank shaped-charge rounds do not do as well when spinning. They want everything in a tight circle.
If your projectile has fins to keep it oriented correctly, then you don’t need to spin it. The whole point of spinning a bullet is to prevent it from tumbling once it leaves the barrel; tailfins accomplish the same task, and so there’s no point to adding spin-inducing rifling to the barrel.
Seems to work ok for sabot shotgun slugs.
Would a bullet with a very heavy tip and a very light mid and rear section also be prevented from tumbling once it leaves the barrel?
I prefer to pronounce it as a word but people look at me weird.
You’ve just described the Foster slug.
Point taken bout the Le Clerc. The leopard had basically the same gun as the Abrams. The trouble with smooth bores is they don’t work that well with heavy full-caliber slugs at long range.
That is true. High Explosive Anti-Tank (HEAT) rounds are far less efficient if spinning as it disrupts the high-velocity jet.
-DF