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XM-25 here we go again...   Army Guns 20+mm

Started 9/11/20 by autogun; 15985 views.
autogun

From: autogun

17/11/20

This would seem to be a useful time to take another look at Metal Storm.

The changes I envisage being needed to achieve this go in the following sequence:

1.   Design a stand-alone shoulder gun without considering any UGL applications.

2.   Switch from the LV to the new medium-velocity (MV) rounds (which MS is already working on). These double the maximum range to 800m, but more importantly halve the trajectory height and projectile flight time to any range, providing far greater practical accuracy.

3.   The only downside with MV ammunition is the increased recoil, since the muzzle velocity is raised to 105-120 m/s. It has been calculated that a weapon firing MV ammunition should weigh at least 5 kg to reduce the recoil to a level which the average soldier will find tolerable. A typical conventional single-barrel 40mm LV launcher, with stock, weighs around 2.5 kg, give or take a bit.

4.   If the weight needs to be doubled to cope with MV ammunition, then a virtue can be made from necessity by giving it two barrels. This would not only double the "magazine" capacity, it would provide the option of loading each barrel with different ammunition – say, HE in one barrel, shot or flechette rounds in the other for close-quarter fighting – with the choice between them being made at the flick of a switch.

5.  Since there is no need to provide space for a reloading mechanism, there is no reason to provide a conventional stock or even a receiver. The weapon could simply consist of the two barrels (stacked one above the other), a combined breech mechanism and very short butt attached to the back end, and a skeleton framework clamped to the barrel, supporting Picatinny rails. The breech block could flip open sideways to permit reloading (and incidentally, unlike the 3GL, there would be no restriction on the length of the rounds which could be loaded). The back of the breechblock, which forms the butt, could either be thickly padded or if necessary fitted with an hydraulic recoil damper. This layout would save the weight of the stock and allow the barrels to be significantly longer while keeping the overall length of the weapon short. This would provide space for more than three rounds per barrel – at least four, and possibly up to six depending on weight considerations and possibly on the acceptable degree of variation in muzzle velocity.

6.   Some other details: the Picatinny rails would include electrical contacts. This would mean that the pistol grip unit – which would include the trigger, safety, barrel selector and battery – could be attached anywhere on the underside rail to adjust the length of pull to the user's choice. The location of the forward handgrip/bipod, sights and cheek-piece could be similarly adjusted. The electrical contacts would also facilitate the addition of STK's air-burst system, using fuze setters on the muzzle.

7.   Safety concerns about having the breech so close to the firer's head could be addressed not only by safety interlocks to prevent the gun from being fired unless the breech is securely locked, but also by fitting a Kevlar shield.

The potential advantages of such a weapon appear to be considerable. Compared with the obvious rivals – the six-shot revolver GLs – it would be far more compact, much faster-firing, have a larger ammunition capacity and would offer the instant availability of two different ammunition types. A tactical option, depending on the circumstances, could be to keep one barrel loaded and leave the other free to single-load specialised rounds such as flare, smoke, or video reconnaissance types. With the STK grenade range to choose from, it would be very cheap to pick any existing projectiles (including less-lethal types for riot control) and attach the MS propellant/gas seal unit to them. The use of shot projectiles – or the development of multiple flechette loadings – would provide a devastating close-quarter battle capability which, with at least eight rounds available, could make the carrying of a second weapon unnecessary. A heavy single-flechette round could also provide a useful long-range performance against body armour.

Red7272

From: Red7272

17/11/20

There are some fairly practical questions that need to be addressed with metal storm or otherwise. 

Will bounding grenades do?    Much simpler to execute and particularly applicable to systems like metal storm where the round takes quite a pounding before being fired. 

What is the minimum magazine size?   I can see advantages to larger magazines for walking rounds onto a target but the largest magazines in normal usage are about 18 cm maximum, which would suggest 3/4 rounds maximum for normal usage and perhaps a 5/6 round magazine for specific purposes like the extended Russian magazines of the 5.45.

MV grenades appear to be a good candidate for a long recoil mechanism, with or without gas assistance. Even a mechanical pump action could incorporate automatic long recoil opening of the breech and mechanical closing via pump. A long recoil buffer could be worked into the metal storm design even with replaceable barrels. 

Farmplinker

From: Farmplinker

17/11/20

I've wondered about a "mini-Goose". Shoulder mounted, 40mm MV, but possibly HV, use a counter mass out the back to reduce recoil.

Red7272

From: Red7272

17/11/20

Farmplinker said:

I've wondered about a "mini-Goose". Shoulder mounted, 40mm MV, but possibly HV, use a counter mass out the back to reduce recoil.

That is called the BUR. No reason to persist with 40 mm with that change.

https://modernfirearms.net/en/grenade-launchers/russia-grenade-launchers/bur-eng/

gatnerd

From: gatnerd

17/11/20

Farmplinker said:

I've wondered about a "mini-Goose". Shoulder mounted, 40mm MV, but possibly HV, use a counter mass out the back to reduce recoil

In reply toRe: msg 57
jxexqx

From: jxexqx

17/11/20

Does anyone remember ARPAD? I think it was swiss and fired 35mm projectile. It was fired like a LAW, resting on the shoulder - it wasn't recoilless but had a long recoil travel over the firers shoulder. I can find a few pictures on-line but most information seems to be from games rather than reality. 

I know it's in one of my ancient Janes Infantry Weapons but I can't recall which . . .

  • Edited 17 November 2020 16:27  by  jxexqx
Red7272

From: Red7272

17/11/20

Looking at these you can see why the M79 became the first grenade launcher. 

In reply toRe: msg 55
Jeff (Jefffar)

From: Jeff (Jefffar)

17/11/20

I think most of us have seen this video, but it deserves to be trotted out again

https://www.youtube.com/watch?v=HyAl9qK3Rlg

Refleks

From: Refleks

17/11/20

Jeff (Jefffar) said:

I think most of us have seen this video, but it deserves to be trotted out again https://www.youtube.com/watch?v=HyAl9qK3Rlg

At that same event IIRC there was a high impulse weapon system that was a single shot 40x53 HV that they mentioned shot flat enough to essentially be POA/POI out to like 300 yards. The video I saw disappeared and I haven't been able to find it, I think it was FN's prototype.

Recoil looked brutal but it seemed to have worked

*edit* found a picture of it


 

  • Edited 17 November 2020 23:38  by  Refleks
gatnerd

From: gatnerd

17/11/20

Found a cleared one:

https://static.wikia.nocookie.net/guns/images/4/4c/HV40.jpg/revision/latest/scale-to-width-down/480?cb=20180414060225

And a brief write up:

https://www.ar15.com/forums/general/A_KICKINandapos__40MM_SYSTEM_question/5-624055/

A KICKIN' 40MM SYSTEM

Never one to disappoint at Shoot-outs, FNH USA took advantage of this year's gathering to introduce the company's new 40mm High-Impulse Weapon System (HIWS), dubbed the High-Velocity 40 (HV-40). This latest addition to FNH's HIWS line is a direct-fire grenade launcher — forget lobbing rounds downrange with this weapon.


An evaluator tests the 40mm High-Impulse Weapon System by FNH USA.
-- Photo by Lloyd Francis Jr., AFJ staff

Designed for use either as a stand-alone system or mounted as a modular undercarriage launcher, the HV-40 fires both the high-velocity rounds used in MK-19 automatic grenade launchers and the low-velocity ammo designed for M-79s and M-203s. The high-velocity rounds sail out to 2,000 meters, and have an effective engagement range of 600 meters.

Last year, some readers will recall, FNH introduced AFJ evaluators to a 76mm HIWS, which made for some interesting video of evaluators losing contact with the ground as they launched 2.2-pound payloads from the 3.3-pound 76mm round. This year's half-size cousin of the 76 HIWS looked far less formidable, but still left shooters knowing they had fired something out of the ordinary.

The folks at FNH are still refining the design of the prototype, proof-of-concept HV-40 unveiled at this year's Shoot-out. The system currently weighs about 17 pounds; its target weight is 15 pounds. It's 31 inches long and, without its sight, 9.25 inches high. A three-round, magazine-fed prototype is under development.

After firing some standard 40mm high-velocity training ammo (722 fps) from this shoulder-held weapon, our noble band of evaluator-warriors have one universal recommendation for FNH: reduce the weapon's recoil. Other than that, they loved it.

"A helluva kick, but it puts the 40mm right on target!" wrote one. "Excellent accuracy. The HIWS takes the 40mm round — designed for area-suppression fire — and turns it into a precision projectile."

Noted another: "A little rough, but it's only a prototype. It provides a useful 40mm capability in a portable system. Recoil is severe, but manageable. A better stock design is needed to improve ergonomics."

"Very hard recoil; not a fun gun to shoot," said another.
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