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MaadiMan's play-by-play MG47 build thread

11K views 33 replies 11 participants last post by  MaadiMan 
#1 ·
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.
 
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#3 ·
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 cel 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):
 
#8 ·
I got a little bit done today in between taking the younguns to soccer and starting a batch of biodiesel. I used my flapper wheel to smooth out the weld on the receiver's seam:


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:
 
#11 ·
I went over to Sharpsshooter5090's house last night for a hands on session with his belt-fed projects. Thanks SS! (It was only last night that I realized your name is Sharpsshooter, Sharps-shooter not sharpshooter! Shows how observant I am!)

It was a real treat to be able to see all of his toys. Plus I was able to see and better understand how all of the parts fit together and work together in his MG47s. I'm gonna get cracking pretty good now.
 
#12 · (Edited)
SHARPS-SHOOTER-50-90

Sure, no problem. glad you could make it.

Sharpsshooter5090 came from the gun I use for elk hunting, a Sharps rifle in 50-90 caliber.




I went over to Sharpsshooter5090's house last night for a hands on session with his belt-fed projects. Thanks SS! (It was only last night that I realized your name is Sharpsshooter, Sharps-shooter not sharpshooter! Shows how observant I am!)

It was a real treat to be able to see all of his toys. Plus I was able to see and better understand how all of the parts fit together and work together in his MG47s. I'm gonna get cracking pretty good now.
 
#14 ·
I've got a little bit done in the last few days. I'm pretty busy right now trying to make enough biodiesel to power my F350 and my K5 Blazer next weekend when I take my family down to Moab for some hiking, camping and 4x4ing.

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:

 
#17 ·
looks like it is coming along well. Looking forward to seeing more pics as the build progresses.

If it isn't to much to ask - maybe you could do a pictorial on making biodiesel sometime. :)
 
#18 ·
I got a little bit of work done last night. I got the adapter built (the adapter that connects the trunnion to the reciever). I'll get some pics up soon.
looks like it is coming along well. Looking forward to seeing more pics as the build progresses.

If it isn't to much to ask - maybe you could do a pictorial on making biodiesel sometime. :)
Sure! I'd love to B.S. about the bio.
 
#19 ·
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,
 
#20 ·
Don't panic!

Drill the screws to the pilot size for the next size down; 8-32 if you're using 10-32. Then insert an 8-32 tap.

The broken screws may come out while tapping. If not, run an 8-32 Allen screw in from whichever side stands clear of the trunnion, then use the wrench to crank it out.
 
#23 ·
Cool. Thanks for the offer, SS. I'm going to take a little while to recover after the rafting trip before I start working on this progect again. I got ground up on the rocks under a waterfall! I got tossed out, and sent through the spin cycle on the sharp rocks. I've got road-rash all over my right side. I've got bruises, scrapes, and cuts on my knee, lower back, shoulder, elbow, right hand, and a pretty good goose-egg on my noggin! I'm moving pretty slowly today!

It was a fun trip in spite of the casualties! My 4-year old son got thrown in the same place, but his worst injury was the loss of his Florida Marlins hat. After I got him and the raft gathered up again, he told me that he didn't like the river,
"It's mean. It took my hat."

I think I'll get some pictures of the trunnion adapter (and maybe some of the carnage) posted tomorrow.
 
#24 ·
This has been a busy summer! I've not had a lot of time to play with the MG47. My wife had a bunch of triathlons, and bike races, so I got to be mommy while she trained and competed.

Then on the last race of the season for her, another competitor passed her and clippled her front tire. She went down hard on the pavement (at about 22 MPH) and broke her scapula and clavicle both! Ouch! She had to have surgery to put her collar bone back together. The surgeon told me that there were 2 main peices of bone, but that there were also 2 shards that were big enough that he "keyed them together", then he fastened it all down with a titanium plate and screws. Here's the pic before they fixed her:



Sept. was supposed to be all for me; 3-gun shoots, bowling pin shoots, Blazer-Bash in Moab, and a lot of gun and truck building, but now I get to be mommy to Mommy and the 4 younguns. I've been trying to be upbeat and supportive, but Mama is pretty grouchy right now. I hope she heals quickly.
 
#27 ·
Thanks for the well wishes.

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.
 
#28 ·
Here's where I'm at right now:

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.
 
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