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belt feed ak-47

130K views 770 replies 90 participants last post by  Warwickben 
#1 ·
I just recentlly finished a beltfeed ak-47 base fire arm with a scratch built receiver, a MG-3 top cover/belt feed mechanism, FAL fcg, scratch built stock, grip frame & grips and forearm, k98 rear sight and m60 return spring. You can see photos of it on PHOTOBUCKET, search for 300 WSM FAL or SHARPSSHOOTER5090.
 
#3 ·
Very interesting concept. and a real eye catcher. Perhaps those spare parts I have sitting around can be turned into something usefull. Hmmm?
 
#6 ·
Guess it ejects on the left side? Any problems with ejecting and the drum?
 
#8 ·
that does look sharp! :)
 
#10 ·
The barrel, trunion, bolt, and bolt carrier are ak-47. The receiver is scratch built form 1 1/2' by 2' retangular steel tubing. The bolt carrier has a piece welded on the back of it for a m_60 return spring to connect to. The weld piece aslo has a slot machined into the bottom for an extended FAL hammer to swing into to stike a spring retun extended ak firing pin. On top of the welded piece is mounted a roller that rided in the feed cam slot of aMG-3 top cover/feed mechanism. The gas tube is made out of a 12 ga barrel section and a larger gas piston is silver soldered to the originial ak gas piston to give the bolt carrier extra push to operate the beltfeed. The belt is MG3 which holds the 7.62x39 cartridge not as tight as a RPD belt. The gas relief holes in the gas tube are drilled at the end of the gas piston stroke to make the system a long stroke piston, again to give the bolt carrier extra push to operate the feed mechanim. It ejects down low to the left and the ejected cartridges just miss the SAW-249 50 round cloth cartridge bag. Rear sight is K98. There is a front barrel extension fitte to the ak barrel to keep the pressure up longer inorder to aid in operating the feed mechanim. The butt stock, pistol grip assy and the forearm are scratch built. The fcg is FAL. Flash hider is L1A1. The gas port is drilled out to .187 dia. The bi-pod is import RPK style. The feed tray is alto scratch built.
 
#17 ·
RELIABLE CYCLING

I want to install a longer barrel in order to keep the pressure in the barrel/gas piston up longer to more reliablly cycle the bolt carrier all the way back. Right now, it moves back just enough to cycle but not always. I have opened up the gas port but the pressure drop off too quickly because of the shortness of a standard AK barrel. The barrel appears longer but thats because there is an extension on the front that is larger than the bore and a point of pressure loss.
 
#18 ·
You must have read my mind - I was going to suggest a longer barrel, but thought it might be taken as nitpicking :)

Now that you mention it!!!....

You could do well, I think, with a 24" barrel which is a standard RPK size. Give it a longer piston, like a PSL/Dragunov piston length, and give it a longer gas tube. That would increase velocity a considerable amount, something like around 200-400 FPS, and that would no doubt help.

You could use any 7.62x54r sized barrel, which means any Mosin barrel rebuild option that is out there. Chamber it up and lathe it to the right diameters, "done".


The problem - obviously - is that you have is that the 7.62x39 just doesn't have that much power, and you've reverse-engineered a recoil-operated system into a gas-operated system. That in itself shouldn't be too great a concern, considering the FN Minimi, and the Stoner 63, and the fact that there is a 5.56 version of the MG-42 which was a Spanish design IIRC.

Do you know the muzzle velocity?


I wonder if you can benefit from a muzzle booster, like an AKSU (aka Krinkov) style booster? Would be worth a try, that expansion chamber was designed to boost velocity on the AK-74 based design, so in theory it would help your design as well.

I also wonder if you have the "hammer hump" problem? That seriously robs my .308 bullpup of power to the point that it doesn't always reliably feed. Grind the hump and try it- you never know.

Also, what kind of piston do you have? Home made? Original factory? Reason I ask is that if the piston bleeds enough gas by being narrow enough to make a poor seal, it will let enough gas bleed-off to affect functionality. I had an AK-74 malfunction due to a piston I made being too narrow diameter. Possibly a longer piston head would help, I don't know.


Yes I've put a great deal of thought into this before!!! :D I really do want to build something similar to yours.
 
#19 ·
AK-47 BELT FEED

All good points. An RPD works with the low power 7.62x39 so this should work also if I get all the variables right. The gas tube is made from a 12 ga. barrel and the gas piston has only .005 to .010" diameter clearance and is about .875 " long. The stroke is as long as the beltfeed cam allows and the gas releaf hole in the gas tube is right at the end of the stroke. I wish I knew what the internial pressure curve v.s. barrel length is. I am not sure that the standard gas block placment from the breach is optimal or needs to move either forward or aft. I do need to make a tighter seal of the gas tube to the gas block though. I am defentlly loseing some pressure there. The hammer cocking hump is just large enough to assure reliable re-cocking. I have some thought of installing a roller on the hump to reduce friction. I have only tried it with the 124 gr bullets but I am going to try the 154 gr soft point bullets. The heaver bullets should have higher pressure if the powder charge is the same.
 
#26 ·
SHARPSSHOOTER5090 - This is a nice build and I see myself coming back to this thread over and over. It is definitely a very nice build that looks well thought out. :thumbup1:

For posting pics from photobucket just copy and paste the line of code under IMG code (that is in pale yellow and begins with [IMG and ends with a /IMG]into a post here and your pics will show up.

If you need any help with posting pics, videos or anything else forum related - ask away as we are all willing to help. And to satisfy some of those that want more pics of this awesome build here are some. :)



I'm looking forward to seeing some of your other projects. Can you give anymore info on the 300 WSM FAL?
 
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