US-made trunion?
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Thread: US-made trunion?

  1. #1
    Happy Camper hcpookie's Avatar
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    Default US-made trunion?

    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.

  2. #2
    AK-74Freak's Avatar
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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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    mike26038's Avatar
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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????
    Last edited by mike26038; 04-07-2004 at 12:50 AM.

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    Master Endmill Breaker Rhino_66's Avatar
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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 hcpookie's Avatar
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    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

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    mike26038's Avatar
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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 Rhino_66's Avatar
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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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    Gunco Regular tarawa's Avatar
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    Quote Originally Posted by AK-74Freak
    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.
    Life Is For Service

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    Happy Camper hcpookie's Avatar
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    Quote Originally Posted by mike26038
    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?

  11. #10
    mike26038's Avatar
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    Quote Originally Posted by hcpookie
    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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