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Squad Support Weapon   Army Guns 20+mm

Started 17-Jun by stancrist; 22564 views.
schnuersi

From: schnuersi

10-Jul

EmericD said:

the US is setting the trend in weapons & ammo.

I really think this is a very important factor in a lot of procurement decisions. Some things are en vogue and considered cool. So a modern military must have them.
The under barrel grenade launcher is a perfect example IMHO.
Originially the German Army did use rifle grenades. A grenade launcher for 40x46 was introduced in the '70 and the rifle grenades phased out. Regardless the G3 and the G36 both have the capability to use rifle greandes.
In the '90 there was conciderable dissatisfaction due to the fact that the US used the "cool" under barrel grenade launchers and "we" had to do with a old style grenade launcher. There was no sensible reason behind it. Just the fact that a UBGL looks cooler and was a newer piece of kit. The GL we had did the same, actually it was better compared to the M203 use at the time and is more flexible. But there was so much noise that after the adoption of the G36 a UBGL for it was adopted. The GLs did not go away though. They are still used in addition.

Something similar happened not long ago. The KSK just had to have M134. Which has now been accepted into service as the MG6. For no good reason other than "we want what they have".

JesseH1234

From: JesseH1234

10-Jul

schnuersi said:

A 30x173 mm cannon with APFSDS is conciderable more potent as an anti vehicle weapons.

Sorry, but I beg to differ. EASIER TO HIT WITH IF YOU HAVE IT?  Yes.  But a 500 gram AC58 can-optimally-penetrate 3-5x what the-optimal-point blank capabilities of an autocannon can.  Cannons are not immune to issues of angle and range.  Also I never said a rifle grenade was an optimal "antitank" system, I'm just saying something like an AC58 enables each soldier to at least threaten an aweful lot of things. 

I didn't even imagine this point would be controversial, there was this thing a while back called the panzerfaust and HEATs have gotten a lot better since.  All I wanted to know was if Emeric thought the recoil made French soldiers hesitant to use (ie practice) with rifle grenades.

17thfabn

From: 17thfabn

10-Jul

Going off on a tangent a little bit.

Why does the U.S. TEND  to use HEDP to the exclusion of HE in its 40 MM grenades?

HEDP  has its place. But with Javelin missiles, LAWS rockets, AT4 etc. for anti armor work the U.S. would seem well equipped with man portable anti armor weapons.

It would seem a well designed HE, optimized for fragmentation would be more useful against personnel than a HEDP. 

Troops could still carry  some HEDP.  They would be useful for enemy behind cover and light vehicles.

Since I'm on a tangent. How much effect does a 40 MM HEDP have after penetrating cover? Say a cinder block wall, a couple of sand bags or car door?

It seems to me that for many situations a pure HE with good fragmentation is better.

schnuersi

From: schnuersi

11-Jul

JesseH1234 said:

But a 500 gram AC58 can-optimally-penetrate 3-5x what the-optimal-point blank capabilities of an autocannon can.

Yes, theoretically. But this number tells you nothing of how effective it is at doing damage behind armor or knocking targets out.

JesseH1234 said:

Cannons are not immune to issues of angle and range.

So are rifle grenades or really any missile.

JesseH1234 said:

I'm just saying something like an AC58 enables each soldier to at least threaten an aweful lot of things.

But it doesn't. Even against light armored targets because of the very thin and low mass jet unless the jet hits somthing really vulnurable and importatent the effect will be zero even if armor is penetrated. If the target is equiped with a spall liner chances are the effect behind armor really is zero.

JesseH1234 said:

I didn't even imagine this point would be controversial

Its not. Everybody knows they are ineffective. This is why almost nobody uses them anymore.

JesseH1234 said:

there was this thing a while back called the panzerfaust and HEATs have gotten a lot better since.

Yes sure BUT they also got a lot heavier. Even back in the day the PG7 warhead for the RPG 7 weights more than 2 kg. Which is more than four times the weigt of a typical AT rifle grenade. The PG7 warhead is hideously outdated and generally concidered ineffective against anything but lightly protected targets.
The Panzerfaust 3 warhead that is effective in UA weights more than 4 kg. Its a completly different league. Much more explosive, much higher liner mass, much more complex design.
Even back in the day simple light HEAT warheads have been known to be notoriously unreliable in behind armor effect. That was befor spall liners and composit armor becaume widespread and quasi standard.

The raw penetration numbers people often focus on are basically useless. Because its only half of what a warhead needs to do. Drilling the hole is step one. Step two is destroying what is behind. This is where simple HEAT warheads fail.

schnuersi

From: schnuersi

11-Jul

17thfabn said:

Since I'm on a tangent. How much effect does a 40 MM HEDP have after penetrating cover? Say a cinder block wall, a couple of sand bags or car door?

A typical car door is basically the ideal case for a 40 mm HEDP. It will easily penetrate, even with fragments and the jet will endager anyone standing in the extension of the trajectory.
On the other hand sand bags are the worst case. They will absorb the blast, fragments and are notoriously problematic to penetrate with HEAT. A double row of sandbags has good chances of swallowing a greande. Parts of the jet might penetrate but its power is low and it will only endanger unprotected personell directly in its path for a couple of cm. Maybe one meter.
Cinder block walls are in between. It depends a lot on the exact type of cinder and constuction method used. Massive cinders made from burned clay are pretty tough and will offer significant protectecion. Especially in a double or more row. The hollow ones made from pressed material are less resillient and depending of how many rows and if they are filled with concrete will not even stop all fragments.

Regardless the HEAT effect of a 40 mm HEDP is really low. Its penetration is good on paper but the behind armor effect is really bad.

17thfabn said:

Why does the U.S. TEND to use HEDP to the exclusion of HE in its 40 MM grenades?

For standardisation reasons. It makes logistics much simpler. The HEDP also is mostly used for the AGLs. Where it makes some sense. 40 mm HEDP can penetrate the typical armor of a Soviet designed legacy AFV except for MBTs. While the effect of a single hit is low an AGL would engage with bursts or sustained fire and can compensate by saturation. This gives a 40 mm AGL comparable capabilities to a .50 cal.
This is the original idea at least.
Ever realised that allmost no AGL is equiped with dual feed?
Issuing them to infantry men to use in their GLs follows the same idea. It means the grenadier only carries one type of ammo. Which is at least somewhat effective all the time against all types of targets. It simplifies logistics and training.
There are a lot of weapon systems and munitions that are designed that way. One prominent example used to be the 120 mm tank gun. Only two types of ammo APFSDS and multi prupose which is a HEAT-MP type. Less then optimal anti soft target effect and fragmentation was accepted for armor penetration to make the shell effective against light and medium armor.

renatohm

From: renatohm

11-Jul

Same situation as the 40mm duo - big bro is too powerful for individual weapons.

Thinking again on this, maybe a Neopup derivative firing the bigger 25mm could be a good choice.

schnuersi

From: schnuersi

11-Jul

renatohm said:

Thinking again on this, maybe a Neopup derivative firing the bigger 25mm could be a good choice.

It could even use a 30 mm grenade.
The Neopup IMHO suffers from the fact that they wanted high MV for long range and penetration. The Neopup launches the 20x42 at higher speeds than a 40x53 is typically fired. The recoil impulse is massive. In the region of typical for rifle grenades. The recoil mechanism compensates for this so we can assume this level of impulse is acceptable for such a weapon.
The 110 g 20 mm grenade is launched at ~300 m/s. Which results in a recoil impulse in the area of 30 Ns. So a 300 g grenade launched at 100 m/s would be possible for such a weapon.
It comes down to what trajectory and what payload is required.

EmericD

From: EmericD

11-Jul

schnuersi said:

Its not. Everybody knows they are ineffective. This is why almost nobody uses them anymore.

Given the fact that most western armies stopped using RGs, only to replace them with the 40 x 46 mm HEDP which is even less effective, I don't think that "RGs lack of effectiveness" was a real criteria.

schnuersi

From: schnuersi

11-Jul

EmericD said:

I don't think that "RGs lack of effectiveness" was a real criteria.

Agreed.
But the other way round: if they were effective they might have not been replaced. Especially not by something even less effective in the AT role.
The idea of using grenade launchers as AT weapons was abandoned.

EmericD

From: EmericD

11-Jul

schnuersi said:

But the other way round: if they were effective they might have not been replaced. Especially not by something even less effective in the AT role.

Clearly, at the time RGs were dropped, they were considered ineffective against tanks.

But at this same time, the 40 x 46 mm HEDP was considered effective against all other light vehicles (or at least sufficient), and THAT is no longer the case...

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