Last Post: 09/14/2010
Retrieved: 01/25/2011
I've been bitten with the belt-fed bug. I've decided to try my hand at building a semi-auto AK-based (loosely) beltfed rifle. My starting point was this:
It's a Romy G kit with an RPD barrel that's been turned down to accept milled Type3 barrel bits. It bores me.
So I got this:
It's an RPD topcover, feedtray, and 100 round belt. My plan is to join the two in an unholy union, otherwise known as an MG47.
The first step I did was to tackle building a reciever. I built it out of .050" thick 4130 sheet. Here I'm bending it on my super-cheap $35 Harbor Freight brake:
Then I welded up the seam. The seam is on the top surface, so most of it will be cut away and covered by the topcover. I left the piece intentionally long so that I can rivet the trunnion back about 1/3 the length from the front, and have a built in handguard. Kind of a 1 piece receiver/handguard/barrel-shroud like an MG43. Only shorter.
And here it is mocked up with my belt full of empty brass and the topcover/feedtray to give y'all an idea of where I plan on mounting it on the receiver.
On to the next step; Demilling the AK
Here stands the condemned:
Post demil after I pressed off the sight block, gas block, removed the handguard retainer, then reinstalled the gas block, and then put the sight block on upside-down:
Crappy cell phone pic after I cut the charging handle off. I also cut off the bottom 2 rivet holes on the trunnion (the feedtray has to go there):
Since my mill is packed up and not accessable right now, I used the angle- grinder to cut down the top (bottom) of the rear sight block, so it would fit inside the new receiver. I haven't yet figured out what I'm going to do for the gas-tube, but I figured it would be good to retain the option to still use the gas-tube retainer on the rear sight block:
Then I took a better picture of where I'm at with the trunnion trimming. I still have to cut the ears down a bit more to get the bullet guide to fit up tight into the feed-tray:
I cut a slot in the top of the reciever under where the topcover will sit:
Then I cut the sides down where the feedtray would sit:
Next, I built a little "bridge" out of some 1/8" steel plate. This is going to straddle the trunnion, and fill in the gap between the receiver (it's 1.5" wide ID) and the trunnion (1.25" ID). I'm going to trim it down a lot. It's also going to hold the little ear that the topcover and feedtray pin to. It will ultimately be riveted to the trunnion and receiver:
Lastly, I trimmed down the sides of the trunnion so that it was 1.25" all the way up. My mill is still inacessable, so I just used a grinder:
I ran into a little snag last night. I pressed the barrel out of the trunnion, tapped the rivet holes for 10/32 screws, drilled the holes in the adapter, then when I was screwing in the stainless steel screws to check for fit, two of the screws took exception to the idea, and froze up in the trunnion. They were so soft that the heads twisted off with way less force than it should have taken. So now I'm probably going to have to drill out the screw stubs, then tap the holes for a larger screw size (14 maybe?). Again, no pics, as the wife had the camera in the truck on the other end of town,
OK, I got a little actual work done on this! Yay for me!
I got the broken screw drilled out, then I re-tapped the hole:
Then I cleaned up the trunnion with the mill:
Then I worked on attatching the "bridge":
I drilled a hole for a rosette weld:
Then I welded up the holes:
I got the barrel/trunnion installed so I have a better idea where the topcover needs to sit. I found that I mounted the barrel/trunnion a bit too low in the reciever, so I'll either have to cut out the bridge and reweld it, or cut down the top of the reciever, allowing the topcover to sit lower. I think I'll go the latter route. I didn't get any pics of it as Mamma needed some help. More to come soon.
It's starting to look like something fun!
Here's the closeup of the "bridge":
The next step will be to cut down the height of the reciever so that the topcover sits down level with the feedtray. Then comes the rails and bolt carrier mods.