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pkt reciever reweld capability?

24K views 108 replies 13 participants last post by  Pryotex 
#1 ·
Has anyone here, re welded a original demilled reciever (obvusally with the proper semi auto actions needed) or would it be better to try to convert a SGMT gory to a pkm style platform? i own a sg 43, but i think its just way too beefy for anything non supported by a carage or tripod .. ideas? in search for a fun bipod beltfed, semi, of corse... PKM's are just so.. badass.. im okay with bastardization, too.
 
#4 · (Edited)
Yes the original receiver on the PKT can be rewelded, you'd have to check at WG to see if there's any info how they are getting the dimensions, if not I can ask the guy from the local gun shop, he's been working on one and I think he got it welded up.
And yes it can be made like a RKM but you'll still have a heavy barrel unless you can find one for a PKM some where.
You need to get or make a stock and mount, put on the pistol grip assemble and add sights.
 
#5 ·
Don't need no stinkin' blueprint! :) Let the parts be the guide - Fit the trunion first, then use the top cover latch to fit the rear section. Relatively simple process for that.

The problems with the PK receivers are that the metal is so thin. Not like welding an MG42. Pirate has receiver flat sections for $50. I made a jig and bent mine up on the press. It needs to have the rails welded in. I am sitting on a pile of springs and other parts that I hope can be fit to eliminate the need for a buffer tube. I refuse to build mine WITH a buffer tube :)
 
#7 ·
They are big U-channels of steel... When you bend the tops over into the top rails, they will be short. The best I have planned (have yet to try) is to cut some strips and weld them to the short top rails. Then grind them smooth top and bottom. You could weld them before bending but I have already bent mine. Don't really think it matters... point is you have to weld something to the too-short top rails to make them work. Unless you intend to use a Vltor-style machined top rail thingy.

Edit - the bottom clearance for the feed pawl is tricky. I did mine with the press and very careful placement of press plates. It isn't as nice as I'd like. I think a better solution would be a machined press plate that has a limiter for the distance to press. Eyeball 1.0 worked for me, however.

pkm

 
#8 ·
#9 ·
Yes that Yugo variant would be fine with a buffer tube :)

I don't know about the PKT vs PKM trunions. As far as I know, the PKT is the vehicle-mount modification, and as such has an electric solenoid activation, as well as a different type of flash hider (the cone-shaped one).

I am unaware as to the trunion design differences, if any. I seriously doubt they would redo the trunions, because why bother if you are simply modifying it to a vehicle mount. Seems like it is just a vehicle modification. Looking at some of the pics of a PKT kit, and PKT pics up close, all the rivet holes look the same. I don't think they are different but would like to know for certain.
 
#10 ·
#11 ·
There is a difference in the trunnions, the PKT doesn't have the cylinder shaped things on the side for the tripod, and it's heavier like they didn't finish machining it.
Here's a pic that Panaceabeachbum posted on WG, PKM on top.
 

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#13 ·
Ah OK I guessed that they would have ground off those tripod lugs. And you are correct, it looks like they simply didn't machine the "lightening cut" on the bottom since weight is not a concern on a vehicle. That, and it provides additional heat sink capability with the extra metal.

I will hazard a guess that the barrels will interchange. The locking tab (the sliding piece) appears to be the same on both.
 
#14 ·
I'm not 100% sure, but I think the barrels interchange.
I was thinking of building one of these just a little while ago, and was reading as much as I could, but since the barrels are all drilled I don't think I want to mess with that.
 
#15 ·
That's my problem too Coils. I'd like a pkm & MORE...but these drilled barrels just turn me away. I know they can be rebuilt, but I just did a quick count of 40+ various parts sets with INTACT barrels in my pile. So maybe I should build those first & see if by then we have a non commmunist president & the parts are flowing again?????:smoke:
 
#17 ·
Ah but don't be so quick to throw out the idea. Remember the PSL/PK barrels can allegedly be built from .303 barrels. You'll have to dig up that thread I started back in 2005 with the "barrel ban". Think BREN barrels now.

Better still - find whomever is making these AK barrels and you should be able to find barrel blanks. A PK barrel isn't far from a barrel blank compared to an AK so there will be less cutting :)

That being said, I have seen where some people are restoring the drilled DSHK barrels. The same concept SHOULD be doable for the smaller caliber PK barrels but I have no idea what all they are doing to them. I suspect they are tapping the holes and installing a screw/bolt section to the edge of the internal bore, then cutting a concave to match the internals of the barrel and leave no open spaces. I did the same thing when I plugged an AK barrel to convert it from a 45-degree gas block to a 90-degree gas block. Doable but tedious. Considering the price of a new barrel, if it works - safely - then why not try.
 
#18 ·
The BREN barrel could be made to work, the only down side is it's a good bit shorter, 23" and it will be shorten a little to rechamber it, so if that's not an issue with a person that would be a good route. But I like that long look of these guns :D
Barrel blanks is the other option, but then there's the length issue again and the diameter, no one makes a blank in that 30" +/- range and most are a good bit smaller in diameter. Most of these medium & heavy machineguns used 30"+ barrels with heavy walls and most blanks are right around 20" or so.
I wish someone would offer longer blanks, I'd save up my pennies and get some of these kits them.

Just went and looked at some specs of the PK series, so everything you just read might have been for nothing. The PKT had the longest barrel at just over 30" and the PK & PKM used a 25"-26" barrel, so it wouldn't be that much shorter if you went with something in the 20" range.


Most of the DSHK barrels I've seen only had two holes in them, one at the chamber and somewhere near the muzzle end. The one at the muzzle was being repaired like you mentioned with a plug threaded & welded in place and I don't see a problem with that since the pressures out that far have dropped a great deal. On the chamber hole the original chamber was being bored out and a .50 BMG chamber was machined to fit, some made their own sleeve, and that's very do-able with a barrel that heavy.
I don't know how well it would hold up in a thinner walled chamber, though the PK series should be ok, and I don't like the idea of just putting a plug in the chamber hole and welding it in place, too much pressure in that area to mess with by just doing a patch job type repair.
 
#19 ·
All very helpful information guys. Any possibility of relineing a barrel with a moisin nagant inner sleeve? I know somebody mentioned that for the SG43's... Also a kit I have... how meaty is the PKT's barrel? enough to be relined and patched?? hell, I'd run a 20 inch. And if I could get machine work. Cut it down a little to save weight.
 
#20 ·
Any possibility of relineing a barrel with a moisin nagant inner sleeve? I know somebody mentioned that for the SG43's...
It can be done if you have the equipment, those guys on WG trying to do it with the SG43's gave up for some reason, so it was never finish.

I don't remember the diameter of the PKT barrel, I know I seen it on WG.
 
#21 ·
Coils I agree with the plug - I would thread the plug and not simply weld something in. That way the threads help seize the plug in place. I really don't think it would blow out with the smaller calibers. We always tell people that drilled into the chamber to just get a new barrel because they are available... if barrels aren't available, then the plug is the only way to go. I would be interested to find out what shear forces threads can take. I know on an engine block when you torque down the threads on the header bolts, the only thing holding the pressures IN is the bolts, so a threaded bolt must be able to handle some pretty good pressures. What pressure is that called? Torque to Yield or something like that? Surely we can find that info to calculate safety margins for a plugged chamber.

Barrel journal is 1.179 on mine. The locking tab that the carry handle presses against is 1.4" but a slip-on collar could be employed to make that little piece. I think that piece is there only to keep the carry hanlde in place anyway.

The problem with a PK is that you will need to set the headspace when you make the barrel. The slot for locking tab (that attaches to the trunion) is machined onto the barrel so you will need to set headspace and cut that notch.
 
#22 ·
The problem with a PK is that you will need to set the headspace when you make the barrel. The slot for locking tab (that attaches to the trunion) is machined onto the barrel so you will need to set headspace and cut that notch.[/QUOTE]

if you made a barrel from a blank wouldnt it be easier to machine the slots then ream until headspace was right?
 
#23 ·
Hello hc,
Multiply the chamber max pressure with the threaded insert bolt cross sectional area to get the max force against the treads. The thread strength will depend upon several things such as bolt material, heat treat, and engaged thread volume. That data may be available in an engineering reference. I couldn't find it in "Machinery's Handbook" or my old engineering texts. You may be able to calculate back from max torque for the particular bolt used. The recommended thread depth is 1.5 times the diameter as a minimum.

All this stuff assumes a rather fat barrel with plenty of meat. The inner tip of the threaded plug must match the surface shape of the chamber or bore perfectly. A chamber reamer may clean it up to the proper surface if that plug is rough shaped very close to final form first in the chamber area.

Also... an interference thread fit would be desirable (vs epoxy or Loctite glue) to retain the threaded plug. That reason being the extreme temps of hot tank bluing which can melt solder or destroy epoxy, CA, etc.

I have used this threaded plug method to save barrels with small holes drilled into them. Run the numbers first for the big holes.

Hope this helps.

VD
 
#24 ·
Thanks VD I am glad I'm not totally off-base :) I was thinking about how accurate the chamber-facing side of the bolt would need to be. In my gas port plug experience, I was able to get the chamber end cut to fit by marking the other end to align with the bore, then take the bolt out and cut on it until it was the proper shape. Of course this means installing, measuring, removing, cutting, repeating, over several times until you get it right.

Assuming you are really wanting to preserve the barrel, I like the idea of first making a bolt to fit, then perhaps sleeving the chamber so that sleeve is always pressing against the plug. That way the cartridges never have to touch the plug! It would certainly make it easier to rebuild. Those PK barrels have plenty of meat on both ends so I think there is plenty to work with.



@akfiend - I think that would be too much work, personally. The extra machining required for the rim support on a PK barrel would mean more time on the lathe/mill... and re-centering every time. If you were to mark the barrel slot location (say with a file), you could make one cut with the mill to get the notch close, then use hand files to get it fit properly.

Or clamp the entire trunion in the mill and machine the slot until the retaining tab closes all the way. Now that I am typing this, it actually sounds easiest :)
 
#26 ·
Got my kit today! I don't care what anybody says, im bringing this thing to life... its beautiful, i told my coworker, when i got it, that the person who cut the reciever was probably crying, and saying they were going to hell... or atleast i would..

demilling old rivits (and keeping them for measurements) and general clean up.. im going to be makeing this as much of a PKM as i can, but, in semi auto.. of course.. the barrel.. hrm, theres a hole, RIGHT in the middle of the shoulder of where a round would sit.. this will probally be the trickyest part.. unless i can find another barrel on gunbroker.. (which i spotted one getting a million bids earlyer this week.. was up to 600 bucks) but the plut closest to the chamber is supported in the trunnion.. so its just a matter of getting it to fit properly with the round, and the trunnion, tapped, threaded, and welded.. i dont see where else it could go. its the gas port one id be worryed about... but atleast thats further away from my FACE

pretty much everything else id need is on gun broker, or referenced on WG to modify.. lets say, the rear trunnion. think i'll be fabbing a trigger houseing out of the exisiting saftey/ whatever that hunk is at the bottom.
 
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