For limited issue in reusable anti-tank weapons, I've decided on up-sized PIAT-type projectors.

However, along the road, I considered (and still am considering) an anti-tank rifle (not designed to knock out MBTs, think of it as an oversized AMR) firing hilariously powerful rounds. 40x364mm Bofors L/70 and 20x311mm necked-down Bofors L/60.

What I was considering was combining an over-shoulder layout with a very long recoil length, and also elements of the HIWS.

The HIWS, from what I can tell watching the Youtube vids, just seems to be the recoiling barrel effectively shoving the round out the breech block at the rear and ejecting it. I was considering having a recoil length of maybe 120-250mm or more (the barrel is going to be up to 1.5m long) to dampen the initial impulse spike, and then a HIWS-style ejector shoves the round out a rear-mounted breech, sending further mass backwards and hopefully minimising recoil. The weapon would feed from 5-round magazines for 40x364 and 7-round magazines for 20x311, and would operate as a slow-loading semi-automatic.

Might work in a gas piston system similar to BARS, just to have that little bit extra - or did someone here once say BARS doesn't work on rounds larger than intermediates?

Uh...

No.

Just no.

Just how would you fire an over the shoulder sniper rifle anyway? I mean, you would have to take your eye off the scope for firing. And that means you would only be able to target things that don't move much.

Worked for the M82A2.
It's designed to knock out things like window emplacements, AFV sensors and if you're really lucky, helicopters. It's not a sniper rifle, it's just closer doctrinally to an AMR than an anti-tank rifle, in the sense it can't physically do much to tank armour.

It's not supposed to make the greatest sense tactically. IC'ly, it's just an SMI works project, like the M82A2 was.

Why did you not make the logical connection that the scope of a shoulder-mounted weapon would be fitted on the side of the receiver?

Becouse I made the logical connection that the scope fitted anywhere on a rifle firing 40mm rounds is going to recoil with the gun and blow the shooters face off (figuratively). I mean, you want the thing to be an over the shoulder weapon becouse no shoulder can contain the recoil. I just did the math (again figuratively).

Hence why I'm asking how much recoil mitigation I'd need, and if mixing HIWS with regular recoiling barrel will work.

The actual HIWS allows you to absorb a recoil force directly into your shoulder, equivalent to "an 80mm mortar". I imagine that's greater than or in the same ballpark as 40 Bofors.

here is what a practical version of what you propose will look like:



thats right a 2pounder AT gun firing measly 40×304mm ammo with a some what large recoil recuperator.

seriously no matter how much you wank muzzle brakes, extended recoil paths, buffers/recuperators or differential recoil systems a gun for the kidns of roudns you are talking about will have to be on a wheeled mounting

What's wrong with the conventional infantry AT weapons which are both much more effective and much more ergonomic.

Because this was a project thought up partially for the lols, and secondly to be cheaper than a missile. And to use up stocks of 40mm Bofors in L/60 and L/70 format I no longer use.

What's the impulse that can be expected of an 81mm mortar and a Bofors 40 round?
It's claimed by the HIWS' inventor that the system can absorb 80mm mortar recoil, and it just feels as though that would be drastically more than that of an autocannon round.

They are speaking bollocks or at least badly managled marketing fluff.

I cna't be arsed chasing down sources and doing all your maths for you but in terms of muzzle energy an 81mm mortar maxes out at about a third of that of 40mm L70 (114000J vs 461000J).

if you want it clearer than that have fun tracking down propellant weights.

Easiest way to use up your 40mm ammo, just give bofors guns to third line defensive units or stick them on spookyalikes.

At this round size, there's practically no way to fit it into a man-portable weapon. And not one fired on the run for sure. Before you worry about recoil, you have to solve the weight issue. Even if team-portable, you'll have to assemble it on the ground anyway. At which point HIWS has nothing to do with it.

Also, RPG will give you much better performance in all regards. Let's say 1 guy carries the barrel, another the breechblock, 3rd the rest of operating parts, 4th the recoil mount, 5th and 6th front and rear mounts. That's before you enter the rounds at 2.5kg each, so 10 per guy.

So your 10-man team will get 40 rounds - while you could rather have it carry 40 RPG grenades (at 2.0-4.5 kg each), really even more, each more powerful, and a few RPG launchers. And all much much cheaper than the load of magnesium, titanium and composite parts you'll need to keep the weight of your 40mm low enough.

API may work, but it is still not enough to make it practical.

It's ambitious with the rounds you're quoting, but the idea is perfectly sound and everyone who says otherwise is being silly.

To be fair, most of the criticism has been with the round size (and the doctrine, but let's take that as a non-issue - I understand its doctrinal impracticality).

So, assuming the round size goes down to something sane (maybe 20mm USN/20x110mm), would the idea work better then? It's closer to a man-portable round, at any rate.

There are 25mm rifles that can be sort of fired by standing men.

so work out the problem for him-- because all these silly people with their physics and math say it cant be done.

OR

maybe youre wrong.


Samo, yeah 20mm is far more doable in this regard.
Lahti L39 is 20x138(about 50kg), Carl Gustav 42(about 15kg, bolt action) sorry Im not really read up on modern AMRs beyond the barret, and I use a Gepard clone.

Well, if we still consider the german 28/37 squeezebore a 'rifle', then sure, go 40mm.

But that would be a flip'n hilarious tripod/wheeled-sledge.

What math and physics? Alright, here's some goddamn math and physics:

1) The Soviet/Russian GsH-301 30mm autocannon from the flanker, which mind you includes an articulated barrel, jam-clearing system and feed system weighs 46 KG; well within what a healthy adult male would be expected to sling around their shoulders (warpac soldiers lugged spg-9s around, and those are about the same mass). A 30mm non-recoilless man-portable or crew-portable does not, therefore, exceed sane mass limits.

The idea of taking shots at distant materiel targets from the shoulder is, however, completely retarded. There will have to be a bipod.

2) The 30x165 generates roughly nine times the total recoil momentum of the 12.7x99mm. Unless you're given to believe in magical momentum-mitigating systems like the KRISS (and if you do, why are you wasting that technology on small arms?), the only way to keep peak force levels to an acceptable level is to spread out the application of the momentum over nine times as much time. Mass times acceleration is force, mass times velocity is momentum, total momentum is the integral of the force/time curve, rate equals distance times time; you don't even need a High School physics education for this. Any Pixies fan knows that.

This, by the way, assumes that 12.7x99mm systems impart the maximum acceptable force levels to a shooter's shoulder.

So, we have a system that's 50% heavier, under 9 times as much total impulse for a total of 4.5 times as much velocity. You just need a really long deceleration track.

wow, so everyone who said he coudnt do a fire the shoulder weapon was being silly...no one said it couldnt be a crew portable weapon.

They said it couldnt be fired from the shoulder-- because of mass, and recoil.

Who gives a shit about the recoil if the weapon isnt going to be fired from the shoulder-

The SPG-9 weighs in at 50+ kg with the bipod and is a two man carry, and weapon is broken down for the carry-- not one man carrying the 46kg assembly and the other carrying the tripod.

Your aircraft cannon doesnt breakdown as easy-- and thus no, it wouldnt be lugged around, and nothing 46kg(unloaded) is going to fired from the shoulder(not to mention the 301 is FAMOUS for its high recoil impulse actually damaging systems on the planes it was mounted on)-- The weapon has free recoil of over 900 ft-lbs.
Might need more than a bipod.

Also 30mm does not equal every 30mm. We fire 40mm rounds from the front of rifles held at the shoulder. No one said a 30mm crew portable system couldnt be done- again. But that the round he wanted to use delivered to much energy to be fired from the shoulder, and substantial recoil mitigation would be required regardless. Which it will, your example proves it-- perhaps you shouldve gotten one of those Pixie fans to do the math for you.

Or you shouldve compared your aircraft cannon to the Lahti L39(which wouldve made far more sense then anything shooting the 12.7x99)(has a free recoil of just 120lbs by the way) since its a cannon doing the work suggested here and IT has comparable weights, and muzzle velocity, but is 20mm instead of 30mm and one only need look at the fucking thing to see a bipod and should fired 30mm of the same velocity is not easily dealt with.
So try comparing anti-tank guns with anti-tank guns...maybe you wont get confused next time.

So youre point was what? You dont actually read shit.

Feed system and turret aren't included in this weight. It's just the barrel, the breechblock and the firing mechanism.

The world needs more squeezebore weapons.

The best option for the size and weight of shell you seem to be after is recoilless.

RT-20 A Croatian 20mm AMR

M18 An American 57mm RR.

Look into using some sort of water or plastic confetti countermass to make it safe for surrounding personnel and for indoor use.

Wouldn't a countermass have to be replaced each shot? This was intended as a self-loading, magazine fed weapon.

You could have the thing be a RAVEN gun, but that's really lolzy and would probably require the gun to be reloaded after every shot.

As a means of most efficiently delivering the most energy from chamber to target, yes; if you can deal with barrel-wear.
-no expendable sabot-material leaching muzzle-energy, and able to safely fire over heads of your own troops

Even non-compressed 'Arrowhead' is pretty efficient, at close ranges.

But APFSDS is better in general.

---

RPG-7V with a saline-pack and some grass shoved up its venturi.

You know you wanna.

If we can build automatic recoilless rifles, we can build semi-automatic RAVENs.

Exactly. The OP never specified that it had to be single man portable, just that it would be fired from an over the shoulder position.

Which I've just shown to be demonstrably wrong for a sufficiently long recoil system... and given figures for the calculation thereof.

Oh, I dunno... maybe the guy standing behind it when it goes skidding across the ground? Or were you under the impression that bipods have some sort of magical glue on the feet that give them infinite coefficient of friction?

Yes, hmmmm... maybe like the inelastic spring loaded cradle described in the OP?

Thank you again for repeating what the OP said; that the system will have to have some sort of peak force mitigation.

By the way, why do we care about free recoil? No, really, think about it and stop bandying about terms you don't understand. We care about peak force because force applied to the shoulder is what's going to potentially injure personnel. We don't care how much kinetic energy the gun would get in a hypothetical inertial frame of reference if it were fired in space. I can't emphasize how much we don't care about that. Yes, I'm sure your online free recoil calculator is necessary. We don't care.

What you care about is the length of the recoil system necessary to gradually decelerate the barrel and breech of the gun at an acceptable rate to keep the force applied to the shoulder at an acceptable level. Given the mass an impulse involved that comes to 4.5 times longer deceleration (depending on spring constants and some other stuff) than seen in the M82. Do I have to spell everything out for you? It's a lot easier to sound condescending about math if you can do it...

The GsH-301 example is to show that it's entirely possible to make a 30x165 weapon light enough to hump. 30x165mm, by the way, is entirely powerful enough, which you would have known if you'd actually looked it up instead of trying to look clever. It's 200 M/S slower than the 30x173 the GAU/8A flings and 30 grams heavier. Inasmuch as trying to defeat modern armor with cannon ammunition has any point at all, it's entirely adequate.

Yes, but the idea here was to be man-portable, and having it be automatically loaded would probably make the thing too heavy. :P

Oh, you still have excess non-penetrating mass with a squeezebore since the outer section has to be soft enough to not wreck the barrel, which isn't exactly conducive to good armor penetration. That is, after all, what the penetrating core is for.



The only difference is that the outer section stays with the actual penetrator instead of falling off like a sabot. :P

Epimachus misses the forest for the trees, but that's neither here nor there.



What's more pertinent is that this problem was already solved long before this thread with the advent of the recoiless rifle and the rocket launcher.

We've seen approximately the extent of man-portable anti-vehicle rifle systems in real life. This is not due to any single point failure, this is an optimization game. You have to put a lot of energy on target in a package that is man-portable. The more energy you attempt to impart, and the more effective you want to be at imparting that energy on an armored target, the more compromises you need to make in designing the weapon system. Weight, size, and ergonomics tend to cut in pretty badly.

The more kinetic energy you need to impart on target from a gun, the more impulse the weapon has to absorb. The more impulse, the longer time (recoil length) the weapon requires for the same recoil force. This can be reduced by size and weight, but these quickly make the system not so man portable, and certainly not capable of being fired offhand.

The HIWS markets decently, but the videos of it ultimately show a device that its designers can't fire effectively. It's knocking people off their feet, it probably relies on Stiction, and leaving those big hollow metal cartridges all over the place isn't a good option.



I'm somewhat perplexed as to the motivation here. M107 style rifles can handle anything short of a Stryker. Once you're in that territory, hopefully you have a Javelin on hand. You certainly should! Being the rifle platoon that you are, you will have a number of AT missiles, plus a fire support asset at the batallion level. If you're a motor rifle platoon, you'll have a company level direct fire support asset in addition to your AT missiles.



EDIT: I see what's going on here: this is a concept driven design. Let's turn this problem on its head. What job are you trying to fill?

Rule-of-cool shoulder-fired AMR.
Point targets for which a rocket may be overkill, but a conventional AMR would be too untimely and generally unwieldy to field against, like an MG in a window.

The concept is, it's already over your shoulder, so just point and shoot, rather than equip, exfil for a clear shot, set up to take the shot and fire, like you would on a conventional AMR.

Don't forget that "anti-tank (rifle)" here is a designation, not an actual intended purpose.

Maybe move this thread to Concepts of Engineering forum?

Why not use a grenade launcher, underbarrel or otherwise?

Low power, and would require training (however slight) to be able to adjust for the significant ballistic drop. In doing so, increasing the amount of time you would be exposed to enemy fire at short range to judge the distance to target.
The point of this is that, so long as they can brace against the recoil, you barely have to account for drop. It's why I was proposing such a hilariously overpowered cartridge.

Any doctrinal question you ask will receive a weak answer, this isn't intended to be a doctrinally sensible system. Largely because I do issue UBGLs, and in that sort of situation, you'd probably level it with artillery or air anyway.

So you want a small bazooka.

For anything where a bazooka is overkill, a hundred thousand dollar gun is much more so.

A few years back there's been a revolutionary automotive invention that eliminates the need to read your speedometer - by introducing two handles, one going through your mouth and the other through your butt, providing insight into your vehicle's dynamics by the ferocity of their thrusts.

I actually don't understand.

Alright, you want rule-of-cool and complex? Try this:

1) Take your UBGL standard grenade, strap a rocket booster to it.

2) Get the ignition timing right so that the motor is going at appreciable speed before the grenade loses much or any of its velocity.

3)?????

4) Profit!

Make a duel-purpose HEAT-HE shell, realize that it's not optimized for either mission, and enjoy your flatter shooting, weaker, and now more complex RPG launcher. Basically a man-pack 2A28 Grom that uses High-Low Propulsion to boost your RPG out the tube.

Or just develop an explosive shell for your AMRs, accept that it'll be weak compared to a grenade, and move on.


....

OR just use the cost of a program such as this instead for training your grenadiers to use a GL proficiently so that they can make quick snap-shots while reflexively adjusting for drop.

To answer that question you have to look at the limitation of rocket launchers and RRs:



Now consider that that backblast bounces off of buildings. Now consider that more than half of the world's population lives in cities and that percentage is growing.

Sure, you could use inert countermass, but that makes the ammo bigger and heavier. RR and rocket ammo is already huge.

I could go on, but I'm obviously too ignorant of math and physics :rolleyes:

How is an MG nest "not worthy" of a projector shot? Or anything behind cover of any sort? The point of these is to take down tanks, and take on hardened targets.



IMO, if they're behind anything bigger than body armor, blast it.

No, you understand details but not the big picture, like most other people in this thread. Namely because you don't have a mission, just a concept and some screaming about how it works in this or that situation.



What mission is this thing intended to do? What can it do better than what other current designs can do? How will it be employed by rifle platoons, the people who will actually use the thing?

Diagram "A" make sense, "B" lacks any useful label data and is pretty much worthless without a description or labels.

Which means jackshit to the various recorded usages of recoilless and rocket propelled munitions within urban areas. Your proposal to use a 30mm shoulder fired cannon is silly. Is it possible? Yes. Is it advisable? Fuck no. Such a system would gain nothing in portability or utility vs a RPG or a RR equipped with a soft launch or countermass system. Your only arguable benefits be would cost and multi-shot ability. Cost is dubious as the initial price of the cannon and its maintenance would catch up to and exceed the costs of a few disposable launchers. As for multi shot, just go with a M202 FLASH type launcher.

What physics? you just copypasted a link from wikipedia.