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.50 Beowulf?

40K views 264 replies 22 participants last post by  TRX 
#1 ·
I'd been planning to do a .50 Beowulf AK with a bent receiver, but a milled Chinese receiver is now laying on my workbench. It's part of some kind of training/DEWATS rifle; the barrel is welded up, the top cover has a few short (and pretty!) TIG welds anchoring it to the receiver, and it's missing the bolt and carrier.

I'll need the following:

.50 barrel

7.62x39 bolt to match the Beowulf case head

bolt carrier and operating rod

.223 magazine (may require some "adjustment" according to the AR15 sites)

modified or full-custom RSB, gas block, and FSB - the .50 barrel would have to be thinned unworkably to match the OEM bits. Though machining them from scratch is okay, I might cheat, saw the rings off, and weld or silver solder them to appropriate-sized tubes

At the moment, the only real point of uncertainty is the barrel attachment - it appears to be threaded into the receiver. I know I saw a chart around somewhere that gave the thread specs, but darned if I can find it now...

Anyone see anything major I've overlooked? Other than the gas and sight blocks, it looks fairly easy.
 
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#205 ·
Nah, I got one of the virgin Yugo trunnions, so all I have to do is press a barrel in and pick a good position for the pin.

A local friend has jumped in, and there's a pile of his parts in boxes in my shop. Once I finally pass from "making tools" to "making parts", we'll be building his as well as mine. Naturally, he's impatient, and hasn't yet realized that here at Sloth HQ, we have no word that conveys the pressing immediacy of "mañana"...
 
#207 ·
For anyone else thinking of doing a big bore, you don't have to use the fat AK barrel pin. The stamped Valmet RK62 used a 4mm rivet that doubled as the barrel pin.

The H&K G3 pin is .200".
I suspose you could plug the existing holes with a tightly pressed in plug and redrill a smaller hole for a smaller pin. I wonder how small you can get away with.

I need to stock up on a few virgin trunions myself.
 
#208 ·
I also recently received a virgin trunnion from Rguns. I remembered I had this Yugo style bent metal blank from AK builder. I'm going to start carving it down to fit the weiger mags I have when my dang back gets a bit better. Heh....Heh

 
#209 ·
By the way; For what it's worth, Cabelas is taking back orders on ammo at around $28.00 a box. I ordered another 8 boxes with my cabelas card points.
 
#212 ·
Last night I tried bending the Tapco flat. Pulling it through was definitely harder than a .039" flat, but it wasn't bad.

Unfortunately, it bent unevenly. The flat didn't slip, but it looks like the baseplate got cocked somehow and it pulled one side down first. All four all-thread rods were bent slightly.

I'm pretty sure I can salvage the flat. I think I need to run some weld along the sides of the bottom plate so it is centered when it starts into the frame. I also need to do something about the alignment of the bending shoe and the bottom plate. First time around, I made it to take standard Tapco flats, and used their extra holes for alignment pins. But the AK-Builder flats don't have those holes, so I removed the pins. None of the Yugo flats have pins. I'll figure something out. At least it wasn't one of my AK-Builder Yugo flats I waited over a year for...
 
#215 ·
I havent said much to this point. But I am watching and rooting for you to hurry up too.!!!

So many projects so little time. I have the stuff siting aside for the 80% cold steel/yugo/450 bushmaster

The VZ58 uses a tiny pin. will have to check it for you this evening if i remember it and my vitamin b-12 shot (to help me to remember)
 
#216 ·
Thanks, I'd appreciate that.

I got the steady rest cut down for the 10" lathe, so I'm that much closer to chambering the barrel. I have the centering plugs almost done; they're a snug fit in the barrel, and I need to countersink the opposite ends so they'll run on centers. I left enough stock so I could center them on the 4-jaw chuck. Once I cut the barrel steps it'll be centered on the bore, so I can run one end in the steady rest and chamber it...

Green Mountain now has 20" barrels in stock for the same price I paid for the 15" barrel a couple of years ago, so if I mess the barrel up I can reserve it for a future pistol build and do a longer rifle barrel...

I kept pushing the Beowulf stuff aside to jump on new projects as they caught my fancy. Now the urge is upon me again...
 
#222 ·
I am making my Beowolf build to look like a regular AK with a fat barrel. Here is how I'm doing the gas block. I made up a fixture to hold the parts exactly paralell & square:
 
#226 ·
Also have to keep the bore centers the same distance apart as original.
This build hurts my brain, but I believe I have most of the hard thinking part behind me.

brad
 
#227 ·
Go, Brad, go!

The bore centers on the gas blocks I've measured vary about .030". With the loose joint on the gas piston and the clearance between the carrier and rails, I guess it doesn't make any difference.

Now show us the after-the-weld picture! I'm still planning on making my gas block in one piece since my welding bites.
 
#228 ·
I was all set to mig weld it until I spotted some gas welding rods at our local feedmill store. I have not gas welded since junior high school in the sixties. But I thought it would be fun to re-learn. With all the new modern welding processes, I kinda forgot about Oxy /acetelene welding. Need to dust off my nozzles! Heh...Heh

And YES I am putting the bayonet mounts back on! Can't have a Zombie killer rifle without a bayo can I????
 
#229 ·
hmmm you do reliaze a RPK gb has about a .807" bore right?????

i just bought two for a heavy barrel build my self.

Your going to see some serious warpage of the the bored part when you weld it. Trust me I have tried this exact same thing your doing. I was able to over come it by having a milling machine an being able to bore the hole last after welding it. i also could have made the sleave extra long to fit in the lathe an bored it an then cut off the extra when done. doing these is a pain inthe ass as you have stated its also why my varmint stuff was made out of a solid block on a mill I was in a super hurry.

I like your jig Id have made the bore smaller initaly a longer to allow you to true it an final size it after welding an then removed the extra part there for chucking in the lathe .

what is your barrel od BTW????????

how are you guys getting around the barrel pin running so close to the chambers if not in it ???????? I had planed on threading the trunion an screwing a barrel in or using a virgin rpk trunion on a large bore build. I didnt go back an read the whole thread.

RPK block cleaning rod hole no zombie bayo lug though.
 

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