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Happy Camper
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Discussion Starter #1
Why not? I would like to try to make an (affordable) RPK front trunion. What metal could be used to make a trunion? Would any old scrap metal work? Obviously, tool steel would be best but I don't know what the billets in my garage are made from. They appear to be hardened steel billets but I have no way of knowing what alloy.

Which brings me to my second idea - got this from Winn's RPK project - what about "shims" that could be placed on a normal trunion (like that $15 K-Var bulgy "discard" trunion - http://www.k-var.com/product.asp?0=205&1=206&3=450).

These shims would provide the extra material to make the normal trunion function with an RPK reciever? The shim would consist of all the "bulged" material on the sides of the RPK trunion, that keeps it from laying flat (compared to a normal trunion). Would this work, or is this asking for trouble? Using this, with a coldsteel4us RPK receiver flat, and the $15 K-Var trunion, would give us an affordable RPK.

I'm thinking this shim could even be silver-soldered to the trunion, but that would impart heat, and I'm not sure if the trunion would like that. OTOH, Winn's toothpick test from many moons ago proved there isn't a great deal of force imparted to the front trunion, so perhaps this would be OK - can anyone think of a reason NOT to do this? It would be a relatively simple mill job... heck, one could even use a file and dremel to make these shims.
 

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coldsteel4us blank?

I have one of his blanks, and I am not impressed with it. Out of spec demensions, His center punched holes are way off, the bends are way too round and the magwell dimples look deformed.
 

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How about making a trunnion with no locking lugs.. Weld a 5.45x39 bolt to the carrier + no lucking lugs on the trunnion= 9mm blowback assembly????
 

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Master Endmill Breaker
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That brand new mill has got the brain juices flowing, hasn't it? Why not make some dies to stamp your Ace blanks into RPK replicas. Then go ahead and make some shims and use any AK kit. How about an RPK-63 (die stamped Ace blank with an AMD-63 kit)? You conquered the rivets with a set of bolt cutters, so why not some receiver dies? You KNOW you want to make some magwell dimple dies on that mill too...

The pics of the coldsteel blanks on eBay looked like crap. Maybe they got better, but the pics didn't show it.

Mike, the 5.45 bolt fits the 9mm perfectly. Save those 5.56 bolts for an actual .223 rifle build. The 5.45 bolts can be had for a few dollars cheaper, too. The 7.62x25 (Tokarev) round also fits the 5.45 bolt perfectly. Be a good excuse to make use of one of the CZ-24/26 barrels (with 5" extension, of course).
 

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Happy Camper
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Discussion Starter #5
Indeed it has! I'm chomping at the bit looking for a good cheap beginner set of mills & other things, then finding boring bar sets, stuff like that, and thinking HRRRMMMM :D
 

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5.45x39 is what I meant to say..

I was doing some looking.. I figure get a 9mm AR-15 bbl. turn it to fit trunnion... Weld the bolt in the carrier, or pin it in some how.. Remove the locking lugd from the trunnion.. Press in bbl., headspace.. and whoala.. 9mm blowback AK..

Don't ask about the mag, havent got that far yet..

Think it would work, or blow up????
 

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Master Endmill Breaker
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I've been kicking a pistol caliber conversion idea around for a long while. This was discussed on Gunsnet and Roderus forums with a few people, so I'm going to start a new thread for this one. Keep an eye out for it.
 

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AK-74Freak said:
coldsteel4us blank?

I have one of his blanks, and I am not impressed with it. Out of spec demensions, His center punched holes are way off, the bends are way too round and the magwell dimples look deformed.
They seem to be the only RPK bentmetals availailable. Some one posted a few pics of an RPK built with one and it looked real nice. They are definately not meant for a beginner.
I am re-bending the corners on mine now. It should work out ok.
 

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Happy Camper
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Discussion Starter #9
mike26038 said:
5.45x39 is what I meant to say..

I was doing some looking.. I figure get a 9mm AR-15 bbl. turn it to fit trunnion... Weld the bolt in the carrier, or pin it in some how.. Remove the locking lugd from the trunnion.. Press in bbl., headspace.. and whoala.. 9mm blowback AK..

Don't ask about the mag, havent got that far yet..

Think it would work, or blow up????
Don't have a lathe... yet.

What is the journal size of that AR-15 9mm at the breech?
 

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hcpookie said:
Don't have a lathe... yet.

What is the journal size of that AR-15 9mm at the breech?
I'm really not sure.. That is something I was going to look at at the nest funshow.. They look like they would be big enough???
 

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Happy Camper
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Discussion Starter #11
If its too thin I'll bet you could turn down an appropriately-sized piece of gas pipe, to make a sleeve to fit over the barrel. Would have to bore or ream out the middle.

Use either a gas pipe, or machine from a solid bar of steel. I went to the scrap yard and found dozens of perfect-sized hardened billets just waiting to be ground down.
 

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hcpookie said:
Why not? I would like to try to make an (affordable) RPK front trunion. What metal could be used to make a trunion? Would any old scrap metal work? Obviously, tool steel would be best but I don't know what the billets in my garage are made from. They appear to be hardened steel billets but I have no way of knowing what alloy.

Which brings me to my second idea - got this from Winn's RPK project - what about "shims" that could be placed on a normal trunion (like that $15 K-Var bulgy "discard" trunion - http://www.k-var.com/product.asp?0=205&1=206&3=450).

These shims would provide the extra material to make the normal trunion function with an RPK reciever? The shim would consist of all the "bulged" material on the sides of the RPK trunion, that keeps it from laying flat (compared to a normal trunion). Would this work, or is this asking for trouble? Using this, with a coldsteel4us RPK receiver flat, and the $15 K-Var trunion, would give us an affordable RPK.

I'm thinking this shim could even be silver-soldered to the trunion, but that would impart heat, and I'm not sure if the trunion would like that. OTOH, Winn's toothpick test from many moons ago proved there isn't a great deal of force imparted to the front trunion, so perhaps this would be OK - can anyone think of a reason NOT to do this? It would be a relatively simple mill job... heck, one could even use a file and dremel to make these shims.
It is possible to shim the smaller RPK trunnion's to fit a regular size AK receiver.

Two shims, each .010, can be installed on each side of the RPK trunnion and it will bring its total width to 1.25 in.. Of course you're wanting to go the other way.

This however doesn't really doesn't address your issue: how to get a reasonably priced RPK 74.

Creating the bulge is not that difficult although I'm indulging in a little mental fantasy now-- I've not done this. Drop the 74 trunnion in there, fill them with a weld, and mill it all smooth. I've never seen the weld heat create a problem with the trunnion.

There's also another way of skinning this cat. I've got a store bought, milled receiver RPK which was justified on the basis of " I gotta know what one looks like ". The milled have straight walls and the lightening cut.

The difficulty I've encountered is locating the RPK 74 barrels.

 

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Happy Camper
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Discussion Starter #13
Winn R said:
There's also another way of skinning this cat. I've got a store bought, milled receiver RPK which was justified on the basis of " I gotta know what one looks like ". The milled have straight walls and the lightening cut.

The difficulty I've encountered is locating the RPK 74 barrels.
Winn! Nice to hear from you.

I've been thinking about the milled route for an RPK-47... there are Arsenal single-stack milled receivers to be found for $270, and would give me most of the parts except the barrel. I'd use my brand-new mini-mill to ream out the mag well, and find a new barrel.

I posted the question about RPK barrel availability on K-var's forum, and was told to call to see what inventory they had on hand. Apparently they have available, or can obtain, RPK barrels if you ask for them.
 

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hcpookie said:
Winn! Nice to hear from you.

I've been thinking about the milled route for an RPK-47... there are Arsenal single-stack milled receivers to be found for $270, and would give me most of the parts except the barrel. I'd use my brand-new mini-mill to ream out the mag well, and find a new barrel.

I posted the question about RPK barrel availability on K-var's forum, and was told to call to see what inventory they had on hand. Apparently they have available, or can obtain, RPK barrels if you ask for them.
Do you mean like this one RPK74 Barrel assembly $329 is a little pricey but then again if no one else has them, lol. Here is a picture
 

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Premium Member
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Rumors of my demise were greatly exaggerated. They left a candle in the window for me and I eventually stumbled in.

This is interesting:

$270 for the receiver
$330 for the barrel
$100 for parts and furniture
Is still less than paid for the milled RPK 47. And this will get you a '74.

Hummmmmg

 

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Happy Camper
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Discussion Starter #16
sniper69 said:
Do you mean like this one RPK74 Barrel assembly $329 is a little pricey but then again if no one else has them, lol. Here is a picture
Pricey indeed! Did you read the fine print? No drift pin holes are drilled, and so the notches for the handguard retainer and barrel pin must be machined/reamed. I think that's a good thing - not a de-milled kit but then again more work....
 
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