7.62mm ASHOT rifle - Part 1: Introduction and visualizing the concept
A few years back I was able to bring the ashot shotgun in the game metro 2033/metro lastlight to real life. The gun utilized a "twist open" locking mechanism so I though migrating this locking mechanism to a rifle would be great, as it is so simple and can be made strong enough to withstand intermediate or even full power cartridge. It's also the reason I design my homemade telescopic 7.62mm ammunition, meant to be used in this firearm
Design criteria:
- Pullbup form factor
- Adjustable parts - Lacking access to precision machinery, I can't manufacture tight tolerance metal parts. There for they should be easily adjustable (headspace, chamber length, stock pull length,... etc).
- Ease of disassembly - I shoot black powder, it's horribly corrosive and gets into every little gap in the gun. There must be a way to easily strip every part to thoroughly clean the rifle before rust kicks in and eat the gun inside out.
- Swappable barrel (I need the same barrel for another project)
Concept
Exploding view
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The barrel is made from 16/7.62mm OD/ID. A section will be turned down to 12mm (same diameter of the cartridge).
Chamber make from 20/12mm OD/ID steel tube (in pink). It slides freely on the 12mm section of the barrel
Like
the Ashot shotgun the locking bolt and nut are located underneath the
chamber, with a twist action to open the breech.
Due to the bottle
neck cartridge and a long barrel, the amount
of bolt thrust is much higher than that of a shotgun. A minor addition
detail is implemented: The bolt at the rear need to be rotate a few
revolution to completely close the breech (I'll explain this in detail
in part 2: Locking mechanism)
The breech made from 20mm solid cylindrical steel bar
The barrel has a collar at the front, make from 20/16mm OD/ID steel pipe. A U slot is cut to accommodate welding material, enhance it's strength
A contraption (modeled in blue) will stop the barrel from flying forward under the force of firing. Why make 2 separate parts and not a single piece? - Metal warping. Under the heat from welding, metal shrink and will no longer be able to slide onto the barrel. So I had to split it into 2 half.
The nut and bolt allow the contraption to move, allow for adjustable head space.
Washer can be inserted between barrel and chamber to accommodate for a longer cartridge. It would also help prevent any gas leak.
Due to the amount of information, I'll split the project into 6 parts
Part 1: Introduction and CAD concept <= You are here
Part 5: Assemble and Firing
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