Military Guns and Ammunition

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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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PDW again   Small Arms <20mm

Started 20/12/20 by DavidPawley; 141521 views.

From: ZailC


Agree, the problem with an overly long forebody is its reaction to yaw on launch. The tip has a long moment arm that delays stabilization resulting in early velocity/energy losses. These loses are amplified by the relatively poorer rotational moment of a long projectile compared with a shorter projectile of the same total mass. Similar losses are to be expected from instabilities on transition to subsonic flight, possibly worse depending on boat-tail design details. Also note that a "good" boat tail can help to minimize yaw on launch amplified by interactions with the reverse flow (out to as much as 10-15 calibers) when compared with square-butted projectiles. 


From: roguetechie


I wanted to say something yes but I'm not convinced that I understand the mechanical situation well enough for my input to be valid...

I've been consulting my reference library and etc as I get time but I've been splitting my attention quite a bit. I just got a new glock kit in and have been working on some other things too so distractions are a part of my issue currently.

As soon as I get this gun built and my new night sights on it (it shipped with just straight up black fronts and rears!) I'll be able to focus more.

In reply toRe: msg 326

From: graylion


Also thinking that the gun should be issued with a shmuzzle, so that if you have time you can attach the can and make the whole thing less of a nuisance to yourself an others.


From: graylion


roguetechie said:

Yeah for what you're doing it should be fine. The solution space you're working in is going to be brute force over absolute aerodynamic refinement anyway and what you've got there is substantially better shaped than most other pdw rounds by quite a bit.

BC is atrocious though because of the low density


From: Red7272


graylion said:

BC is atrocious though because of the low density

You don't need a PDW you can just use a assault rifle like the AK-74u with a thigh holster.


From: gearmrk


The calculator on that website massively miscalculates Meplats.  Can't use it. It miscalculates another parameter as well, but I can't remember at the moment.  It will make you think pointy bullets are great when the optimum low drag Meplat range is 0.08 - 0.12 like someone said earlier.  

Years ago I asked people to stop using that drag calculator due to its issues.  


From: gearmrk


0.15 to 0.18 calibers actually.


From: graylion


Good to know, thanks. Not sure how relevant that is for this design due to short range and brute force approach. Also pointy being useful here because armour penetration.


From: larrikin2


The original 5.7 round was supposedly able to penetrate a NATO standard helmet at 80m and be pretty much nothing more than a bruise at 150mm.

The concept was to give the REMFs a weapon with lots of rounds in it that they could spray in relative safety because they weren't going to have to worry about killing their own side with wild fire.

So deadly when the bad guys over ran your rear echelons and got in close, but harmless at quite a short distance if said REMFs panicked and blasted fire all over the place.

In reply toRe: msg 297
Mr. T (MrT4)

From: Mr. T (MrT4)


So now the 5 and 7'' barrel .300BLK guns are all the rage or what  it seems French are looking for some.

They are looking for 5'' and 7'' barrel options in .300BLK for  Police and Gendarmerie

suppressor ,6 mags , M-lock interface on the forend

300K rounds of supersonic and 600k rounds of subsonic ammo

Modular construction enabling toolless conversion to 5.56mm