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This is intended for people interested in the subject of military guns and their ammunition, with emphasis on automatic weapons.

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20x102 mm cannons   Army Guns 20+mm

Started 22-Oct by Guardsman26; 5852 views.
In reply toRe: msg 20
Guardsman26

From: Guardsman26

24-Oct

Thanks for the responses. Going back to my original post, the US Army is adopting Northrop Grumman's new SkyViper 20x102 mm cannon. What's interesting about this is that it'll be dual-feed with new AP and HE ammunition natures. I also hear that they are looking at lightweight steel and polymer cases. In which case, Stan's observations about ammunition weight relative to 30x113 mm become otiose. The existing 20x102 mm APDS round already has superior penetration to 12.7x99 mm BMG. The existing point detonation HE round is also good. In other words, could ammunition development transform this calibre and make it relevant to today, not only for mounting in aircraft, but also for armoured vehicles to engage infantry, other light vehicles and aerial targets? 

The question is what would 20x102 mm give you that 30x113 mm cannot? I think there are three potential advantages:

1. Kinetic armour penetration versus chemical effect of new APDS with tungsten and depleted uranium options 

2. Better performance against aerial targets due to higher velocity and higher rate of fire (crucial for engaging drones / UAVs)

3. More ammunition carried for the same weight than 30x113 mm

The one advantage of 30x113 mm is its Proximity air burst ammunition. This has a lethal burst radius of around 3 metres. If it were possible to develop a 20x102 mm Prox round, I suspect the lethal burst radius would be 2 metres. This would not be as good, but might be enough to kill a drone, especially when fired in bursts of 5-10 rounds. 

If the collective view here is that 30x113 mm is superior, why is 20x102 mm being considered by the US Army?  in the FARA attack and reconnaissance helicopter and is choosing this calibre over 30x113 mm.  

gatnerd

From: gatnerd

24-Oct

autogun said:

The best 20x102 rounds for penetration will be the APDS developed for the naval Phalanx anti-missile system. The current MK244 as used in the Phalanx 1B looks interesting: it fires a 104.5g 14mm projectile at 1,100 m/s, from longer "optimised gun barrels".

I stumbled across this when looking up '20x102mm penetration' and thought you might like it if you dont have this info/pics already for 'Autocannon.'

https://www.facebook.com/186732938737023/posts/today-we-have-the-main-3-generations-of-apds-20x102mm-armour-piercing-discarding/1054087285334913/

Today we have the main 3 generations of APDS 20x102mm (Armour Piercing Discarding Sabot) projectiles used in the US Navy Phalanx Close In Weapons System, from left to right;

-Orange sabot Mk149 MOD 2 which used a Depleted Uranium armour piercing core

-White sabot Mk149 MOD 4 which was the updated Tungsten cored projectile

-The newest red sabot Mk244 MOD 0 which features a larger, optimized Tungsten core.

The DU cored projectiles were favoured early on in the 80’s for their high armour piercing capabilities and density, which also included an earlier but identical black sabot projectile, the Mk149 MOD 1 (which I unfortunately do not have an example of). The cores were approximately 12mm in diameter and 49mm long. This size would be kept with the later white sabot projectiles as well.

However, it was realized that firing thousands of DU cores into the ocean was not ideal and with the next update came the white sabot Tungsten core Mk149 MOD 4. This removed the DU problem while still retaining density and penetration power to targets. Eventually this design too would be updated with the next iteration.

With the latest update came the Mk244 MOD 0 “ELC” or Enhanced Lethality Cartridge. This kept the Tungsten core, but took advantage of the “empty space” taken up by the sabots and increased the core size from 12mm to 15mm in diameter.

Now some might ask, why use APDS ammunition to destroy missiles, instead of the normal explosive projectiles? Since the Phalanx is a last-ditch effort to destroy incoming missiles targeting the ship, the idea is to destroy as much of the missile as possible without causing a secondary explosion of the missile's warhead. The Tungsten cores punch holes through the missile, tumbling after initial impact and tearing the missile apart, eventually leading to structural failure or disintegration of the missile, all (hopefully) prior to impact.

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In reply toRe: msg 22
gatnerd

From: gatnerd

24-Oct

I came across this very interesting graphic:

Does anyone have:

-Up to date penetration specs for 20x102/x139/25mm?

-Typical armor thickness of modern AFV and IFV's? 

From this slide, we have the penetration spec for 30x113mm is 25mm @ 500m/50 degree. 

gatnerd

From: gatnerd

25-Oct

Guardsman26 said:

Going back to my original post, the US Army is adopting Northrop Grumman's new SkyViper 20x102 mm cannon. What's interesting about this is that it'll be dual-feed with new AP and HE ammunition natures...If the collective view here is that 30x113 mm is superior, why is 20x102 mm being considered by the US Army in the FARA attack and reconnaissance helicopter and is choosing this calibre over 30x113 mm? 

The 'Sky Viper' is Northrops attempt to get in on the action. However the Army has been moving forward so far entirely with a 3 barrel Gatling gun called the XM915, which is appears to be a version of General Dynamics XM301 developed for the Commanche program (which was the previous failed FARA helicopter program.)

https://www.gd-ots.com/armaments/aircraft-guns-gun-systems/xm301/

Being a Gattling, it would likely not have a dual feed, and would just employ the standard 20mm HEI...at which point it would be inferior to 30x113 in penetration and grossly inferior in explosive fragmentation. 

So far its hard to tell why the Army wants a 20mm for FARA, given that they specifically went from 20mm to 30mm when they upgraded from the Cobra to the Apache. 

Possible explanations:

-Somehow 20mm rotary cannon outperforms the 30mm M230 (how we dont know and cant see)

--Weight is an absolute premium for the FARA, and the 80lb 20mm cannon + its slightly lighter ammo + its lower recoil (and therefore lighter mount) combine to produce a worthwhile weight savings for the aircraft. 

-The Army is relying on inertia for the FARA program and is simply re-hashing some of the specs used in the last 3 attempts to replace the Kiowa, the last being the Comanche which had the same lightweight 3 barrel 20mm. This seems cynical, yet the FARA program seems to have crept from scout helicopter to kick in the door peer enemy attack helicopter...little about this program makes that much sense.

....

The Army already had sketchy lethality with the 30mm on the Apache (prompting the development of airbust + enhanced frag) so its really hard to see how 20mm would be anything other than a downgrade for helicopter use.  

https://ndiastorage.blob.core.usgovcloudapi.net/ndia/2014/armaments/WedPaulHill.pdf

  • Edited 25 October 2021 6:05  by  gatnerd
stancrist

From: stancrist

25-Oct

Guardsman26 said:

Going back to my original post, the US Army is adopting Northrop Grumman's new SkyViper 20x102 mm cannon.

I also hear that they are looking at lightweight steel and polymer cases. In which case, Stan's observations about ammunition weight relative to 30x113 mm become otiose. 

My observations about ammo weight would become otiose only if and when steel case and/or polymer case 20x102mm ammo were actually developed, manufactured, adopted, and fielded. 

At present -- and for the foreseeable future -- my observation stands.  stuck_out_tongue_winking_eye

Guardsman26 said:

The existing 20x102 mm APDS round already has superior penetration to 12.7x99 mm BMG. The existing point detonation HE round is also good. In other words, could ammunition development transform this calibre and make it relevant to today, not only for mounting in aircraft, but also for armoured vehicles to engage infantry, other light vehicles and aerial targets? 

For aircraft, perhaps.  For armored vehicles, unlikely.

Guardsman26 said:

The question is what would 20x102 mm give you that 30x113 mm cannot? I think there are three potential advantages:

1. Kinetic armour penetration versus chemical effect of new APDS with tungsten and depleted uranium options 

2. Better performance against aerial targets due to higher velocity and higher rate of fire (crucial for engaging drones / UAVs)

3. More ammunition carried for the same weight than 30x113 mm

1.  Is the armor penetration of 20x102mm APDS sufficient to defeat threat light armored vehicles?

2.  No airburst ammo means a direct hit is necessary, so it is questionable that 20mm would perform better against drones and UAVs than 30mm airburst.

3.  I doubt that the Boxer vehicle would notice the slight difference in ammo weight.

Guardsman26 said:

The one advantage of 30x113 mm is its Proximity air burst ammunition. This has a lethal burst radius of around 3 metres. If it were possible to develop a 20x102 mm Prox round, I suspect the lethal burst radius would be 2 metres. This would not be as good, but might be enough to kill a drone, especially when fired in bursts of 5-10 rounds. 

I think you may be overly optimistic.  The fact that nobody makes 20x102mm airburst ammo seems like a good indication that it is not feasible.

Guardsman26 said:

If the collective view here is that 30x113 mm is superior, why is 20x102 mm being considered by the US Army?

The US Army is considering 20x102mm for scout helicopter armament

They have not considered arming IFVs with a 20mm cannon for ~50 years.

All things considered, fitting the Boxer with a 20mm gun as an "interim" weapon makes absolutely no sense to me.  I cannot imagine that the British Army would seriously entertain such a proposal.

poliorcetes

From: poliorcetes

25-Oct

If the vehicle is enough protected against a 30x113 HEDP, then it is enough valuable. And if it is enough valuable, it will be really more expensive than any ATGM or other future AT system like a loiter UAS.

I just don't understand why in 2021 AP capabilities of auto cannon is taken seriously anymore, given the myriad of AT options. I rather would think that payload capabilities, either cUAS, AP or in general urban fighting is more important by far.

And any 20mm lacks payload capability for using airburst ammunition and thus being a meaningful cUAS / antipersonnel in defilade system

gatnerd

From: gatnerd

25-Oct

poliorcetes said:

I just don't understand why in 2021 AP capabilities of auto cannon is taken seriously anymore, given the myriad of AT options. I rather would think that payload capabilities, either cUAS, AP or in general urban fighting is more important by far.

Autocannon AP ability may return to relevance if there is a proliferation of Active Protection Systems (APS) that make ATGMs unreliable. As far as we know APS doesn't work on screamingly fast APDS/APFDS. I could see that as part of the rationale for the 30x173mm Stryker, as well as the bigger AC's like the 40 CTA and 50-57mm developments the US and Russia are looking into.

But the sorts of vehicles that have APS that could defeat Javelins and other sophisticated ATGMS...more then likely armored well against Autocannons as well. At the least, almost certainly armored agains 'low end' AC's like 20x102. 

Overall as you said, for most realistic / useful light cannon applications (anti infantry, anti drone, anti structure, anti material) the 30mm is really the answer. Maximum HE, moderate recoil, with room for growth in both improving Frag as well as possibly improving the HEDP penetration through a more advanced little copper cone. 

In reply toRe: msg 27
gatnerd

From: gatnerd

25-Oct

In terms of .50's on RWS, is there any merit in switching from the M2 browning to the M3P version, which has 2x the ROF (1100rpm)?

To me this would seem a nice upgrade for the RWS, as it would allow a burst to put roughly 2x the amount of rounds on target in the amount of time as the M2, and the RWS would handle the recoil to ensure accuracy. 

That would seem to improve the chances of hitting moving infantry/vehicles, or having enough rounds hit an armored vehicle that one may disable an important sensor. All while keeping the same basic .50 setup and most of the same logistics.

Browning Fn M3M calibro .50

La prova a fuoco della mitragliatrice Fn M3M calibro .50, erede della leggendaria M2.

smg762

From: smg762

25-Oct

Whats the approximate core diameter of bog-standard .50 AP? (not SLAP) 

stancrist

From: stancrist

25-Oct

gatnerd said:

In terms of .50's on RWS, is there any merit in switching from the M2 browning to the M3P version, which has 2x the ROF (1100rpm)?

To me this would seem a nice upgrade for the RWS, as it would allow a burst to put roughly 2x the amount of rounds on target in the amount of time as the M2... 

That would seem to improve the chances of hitting moving infantry/vehicles... All while keeping the same basic .50 setup and most of the same logistics.

It sounds good in theory, but how much difference does it make in reality?

     M3 - https://youtu.be/gBcvKTYUFq8?t=19

     M2 - https://youtu.be/MWrthRBdhTA?t=1

Switching from the M2 to the M3 would have some significant drawbacks:

1.  It would consume ammo 2X as fast.

2.  It would burn up barrels 10X as fast.

3.  It would require buying a whole bunch of new manufactured M3 guns.

While FN would love the idea, I dunno if the gain would be worth the cost.

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