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.
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?
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.
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 :)
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.
Could you post some pics of your PKT parts kit for us to drool over ??? Also what is the size of the barrel holes and barrel thickness around the holes ??? What a neet Christmas present !!!!
I paid $450 for my spare PKM barrel from Ohio Ordnance Works 6 years ago (wow have I had this kit that long?!?!?) and I think they shot up to $600 right after the "barrel ban" was imposed. Sounds about right, unfortunately.
Does anyone know offhand who is making the existing barrel blanks? I havne't looked... green mountain or someone else perhaps? Using a blank would be MUCH easier...
Yes, i will get you some pictures Viper dude, this actually came in pretty nice shape.. its too bad my OCD is going to make me refinish all the parts... otherwise, the original finish is really nice.. i just got done cutting some weight off the front and rear trunnions.. i probally hacked around atleast half a pound off the front one, and the rear im going to modify for a FAL SAW styled buttstock... polymer, less weight.. and comeone.. SAW buttstocks look sick. pictures when i can, maybe tonight :)
also, Pookie, i have no idea? if you ever end up turning one, i would love to get in on some of that action.. GUNBROKER is selling some of the PKM gas blocks, and id just fab my own front sight.. like i have to anywase. ha... i want to cut down the length and ID of this barrel... but for a repair, im skeptical around those areas.. i wouldnt mind even putting a sleeve Over that area.. im really at a loss with the barrel other then the tap, screw, plug method.
the site i posted a link to earlier has pkm front sights if you just wanna buy one. Cant wait to see the pics. this is gonna be a cool build