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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, particularly in larger calibres (12.7+mm).

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More technical question about gas operation in guns   Small Arms <20mm

Started 25-Oct by tidusyuki; 820 views.
tidusyuki

From: tidusyuki

25-Oct

Just for educational purpose and i'm not looking for any precise number or anything because it obviously need a whole team of engineer. I just wanted to know the basics stuff to help/guide me to learn more about gun design.

I'm gonna narrow it down to basic gas operations like long/short stroke stoner and kalashnikov rotating bolt piston and DI guns

I'm curious how to roughly determine things like:

1. how much gas pressure is needed to operate a piston or an AR bcg so it can cycles

2. how to calculate where and how wide the gas port should be located in the barrel

also is there a specialized field that focuses on firearm engineering?

  • Edited 25 October 2020 10:24  by  tidusyuki
Farmplinker

From: Farmplinker

25-Oct

I think Chinn has some of that in one of the volumes of The Machine Gun.

tidusyuki

From: tidusyuki

26-Oct

Can you elaborate? 

autogun

From: autogun

26-Oct

Volume 4 of Chinn consists of detailed descriptions of the principles of operating systems, with lots of 3-D drawings to illustrate these.

I think you can find all of the Chinn books on the web.

RovingPedant

From: RovingPedant

30-Oct

 

tidusyuki said...

I'm curious how to roughly determine things like:

1. how much gas pressure is needed to operate a piston or an AR bcg so it can cycles

2. how to calculate where and how wide the gas port should be located in the barrel

The answer to both, as far as I can tell, is to either experiment or copy someone else who has already experimented.

The amount of energy needed to cycle the action of a firearm depends on a whole bunch for factors including, but not limited to: mass of moving parts, friction, stiffness of return spring, resistance generated by the feed mechanism.

The amount of energy you can get from the cartridge will depend on a number of factors again including but not limited to: size of cartridge, size of projectile, barrel length, propellant burn profile, gas port location, gas system geometry.

Then you have to consider how these parameters can vary due to fouling (both of the gas system due to propellant residue and the working parts due to environmental conditions) and manufacturing variation.

It’s worth noting that some rifles operate better with some ammunition than others and that many gas systems are adjustable to account for variation in ammunition and condition of the rifle.

You could probably come up with a rough estimate using basic dynamics based on Newtonian mechanics.

 

 

roguetechie

From: roguetechie

1-Nov

Lol no...

You definitely don't have to do it either of those ways.

There's older versions of brasseys small arms design on archive.org. there's also a great internal small arms design doc from the US government available at forgotten weapons , the archive site where the weapons man blog resides now, and or in the smallarms review archive.

There's also copies of the oerlikkon and rheinmetal books out there as well as innumerable other resources freely available multiple places online.

There's literally tens of thousands of pages of small arms design literature with actual formulas and test problems out there in many many places.

Combined with the availability of various American and other military small arms tdp's online as well as some really great compilations of various ar and AK manufacturers gas Port diameters etc which are quite easy to find with simple Google searches... There's absolutely no excuse for trial and error off at best a couple samples measurements.

I highly recommend the smallarmsreview.com archives as a starting point since there's easy a dozen full reference books from Springfield (the armory not the company), the British army, oerlikkon, and more there for the taking.

tidusyuki

From: tidusyuki

6-Nov

So many resources. Thanks!

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