Why do modern tanks have smoothbore main guns?

Awesome and precise explanation. I always knew the general gist of the Brit’s wanting to hold onto HESH, and how rifled barrels were worse for APFSDS, but never knew the physics of why. This is a video I will use as reference for a long time, thank you!

There are two additional advantages smoothbore tanks guns have over rifled ones. The first is that they last a lot longer. There is far less wear on a barrel when a round goes through a smoothbore since it’s not having to force itself through the rifling. This both reduces maintenance costs and can keep a tank fighting in a heavy combat situation. The second is mostly an advantage for Soviet/Russian/Chinese designs in that it’s far easier to fire a gun launched ATGM through a smoothbore. The Soviets began using these for long distance fire as their optics and ballistic computers aren’t near as good as western ones. One of the many flaws of the M551 Sheridan was that its rifled cannon barrel needed a key slot cut through it to keep the missile from spinning when it was fired as spinning would make the guidance fail. This compromised the barrel and made it wear out even faster.

Another advantage with smoothbore is that even when you miss your target entirely, chances are you will still nail your neighbour's dog before having to resort to the canon mounted ontop of your stairs loaded with grapeshot

I find interesting to think that the arrow was invented thousands of years ago and still we go back to it in modern warfare. Edit: In Spain, spanish Leopard 2 crews name apfsds "Flecha": arrow ammo, arrow of war ammo, they name it.

Well this is the first time that I learn that it was the Soviets who invented the APFSDS and used it on the T62. Great video and great explanation

A remarkably well balanced video, especially when compared to so many others that have been made on this topic recently. Bravo!

An interesting footnote that warrants it's own discussion is scale. Smaller guns typically use simpler ammo, since the precision necessary to make fancy bullets is far too expensive for a small projectile measured in millimeters. At the same time, the smaller size means you can fire more projectiles at a time since the forces the machine has to experience will be smaller. Not to mention space. It's honestly fascinating to consider since it explains so much of why we don't just upscale and downscale the same designs over and over.

An additional advantage to smoothbore barrels that I haven't seen mentioned, is that they are easier (therefore cheaper) to produce.

Amazingly simple and clear explanation! I know there's much work behind trying to condense something into an easily understandable package so great work!

Challenger 2 does use APFSDS, but to enable it to fly straight, the petals are banded in a sacrificial ring of plastic which allows it to engage with the chrome rifling, spinning the petals but not the sabot. You could also draw the conclusion that with Challenger 3, higher pressure and projectile speed will be required to defeat future armour and as such barrel life of rifling will be severely reduced (adding cost) and maximum energy needs to be given to the projectile and not lost in friction from rifling. It will be interesting to see what the maximum engagement range will be in the future, HESH was 5km but you could chuck it further with reducing accuracy but the shell didn’t lose its effectiveness. APFSDS was 2km but penetration drops off dramatically beyond that as the round slows down.

I already have a vague idea regarding how APFSDS works but your detailed explanation answered a lot of the questions I have regarding this. Simply brilliant video!

One point in addition to your excellent points on the flexibility of HESH,during the cold war and for some years after the UK had a huge stockpile of 120mm rifled tank rounds,of which some of the older ammunition would have still been useful against older tanks or against the side armour of newer ones. The cost of rebuilding up such a stockpile,whilst still in a cold war with the soviets,would have been significant and risky

The change (or lack thereof) was simply down to the GBs tank doctrine. As mentioned in the video, GB wanted to use their tanks as multi-role, rather than just Anti-Tank. Given the modern state of warfare, I feel like this makes sense.

An excellent presentation comparing the two types of gun on a tank. Compared to other styles of presentation you find on this channel it is delivered clearly, concisely and at a tempo that enables you to take in all of the information. Thank you.

My late brother trained at Bovington. They put animals in a tank and shot it with HESH. The animals all survived. This was in the late sixties.

Essentially they no longer shoot bullets but shoot darts.

One major difference is the lifespan of the guns. The Challenger 2 rifled gun needs replacing after 400 shots while the smooth-bore Rheinmetall gun used by Leopard 2 and Abrams last well over 1500 shots.

Scene 8:57 - You forgot two more types of ammunition that benefit from a smoothbore gun: close in anti-personnel rounds such as the M1028 Canister Cartridge, and cannon-launched guided missiles such as the LAHAT and the 9K112 Kobra.

I was asking myself why the Brits are moving away from HESH with their new Challenger 3 Upgrade since i saw it on the news. Thanks for the clear up and great job on explaining all the different grenades in a very clear and easily understandable way!

with the new programmable HE ammunition, there is really no point of having the rifled gun