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Posted: 7/11/2005 5:04:40 AM EDT
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Well I haven't had this problem in awhile, so I guess I got lazy about it... But, I got two receivers from Global about two weeks ago. I just built a PMKMS on one of them and the receiver is warped all to hell and back. (Which by the way is nearly impossible to fix because these things are so hard, which also happens to be what causes the warping) I got a 5.45 and 7.62 receiver at the same time. Obviously the Polish is built on the 7.62 and the the rear of the receiver cants... pistol grip turned away from the selector side of the weapon. This would piss me off a lot less on a $99 Rommy kit then it does on a $200+ PMKMS kit. So I decided to check the 5.45 receiver which would have been a Tantal build. I tossed a front and rear trunnion in the receiver, slipped a wooden stock on the end and what do ya know, it cants the opposite direction but is clearly warped as well. 10-15 degrees of twist on the stock. (that's a guess obviously, but it is a noticeable cant) So please before you build, check your receiver from Global Trades well. Especially on a folding stock build where the warpage is very noticable when the weapon is all put together. It's hard to see before then as optically you don't have much to go on, but once the barrel is on, with just the block for the folder at the rear, given the two points of optical leverage, you can really see it. Unfortunately I don't know a good way to fix it on these hardened receivers either. It basically makes the whole receiver like a spring. Yeah you can clamp in down in a press or vise and use a large adjustable wrench to twist the receiver body at the rear trunnion and you can get it to twist, but it will pop right back because the metal is so hard. Anyway, doom on me. Don't let it happen to you. I'm going to call Jimmy today and discuss this, I'll update this thread with his resposne tonight. |
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I was under the impression that a hardened reciever especially where the front trunion rivets are is not a good thing. I have read where someone had heat treated this area and later they had cracking issues in the front trunion rivets. I don't know could be BS? I recently helped a member here rivet his AK, and you are right the recievers are like spring steel. Very unforgiving if you need to bend or twist. His had a slight warpage but I didn't think it was enough to be concerned with, the biud went well the only problem was that the Bolt Carrier wanted to come up out of the reciever when pulled to the rear most position. |
| There have been a few posts about heat treat, and warping issues with the Global receivers. Fortunately I have never had that problem. Global receivers are now the only ones I will use. I've read that the problems have been sorted out and that recent batches have been fine. Try contacting Global and see if they will make good on the 5.45 receiver you haven't built on. RTC |
I've seen that commented on elsewhere here. The fix seems to be the installation of a Blackjack-style buffer, which will limit the rearward movement of the carrier. |
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I talked with some of the people in the backroom at GT about the warping just last Friday. It still occurs and they have to cull these out when they return from the heat treater. The mortality rate at times can be high (15-20%) Only problem I continue to see with the GT receivers is the fluctuation in the diameter of the axis pin holes. All in all, still the best readily available receiver on the market. |
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No argument there. My point was and still is, slap some trunnions and a fixed stock on these things and eyeball the hell out of it before you start to build. I thought they were over the warping issues and clearly they are not. Discovering it BEFORE you build is kind of handy, rather than building a $200+ kit or a $400 kit on a receiver that's warped. |
| I just finished two builds on the Arsenal receivers. One straight and one warped. As 2FALable said, I didn't see it, till it was too late. My solution, Clamped it in a padded vise, over twisted it and held it that way as long as i could, than released it and it was straight. It was really frustrating to look down that rifle as see the barrel take a big left turn. Once I figured out it was the receiver that was messed up, I felt better as I knew I could fix that. I've got another Arsenal receiver waiting on a PMKMS kit. Hope I don't have to rack it. |
Wasn't an issue on mine. Didn't measure but the small end of the pin barely went into the small hole, very tight fit there.
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I've measured axis pin holes on 4 new, unbuilt Global 1.0 mm receivers. Please keep in mind that these should be 5mm (0.197 inches) and 7 mm (0.2756). Each hole was measured at a minimum of 4 locations around the circumference of hole. FYI - Some of the pins had a tight feel on the 5mm side as the pins were installed - possibly due to irregularities in hole circularity or burrs. Listed are the ranges of measurements (measurement tolerance 0.001) RECEIVER #1 Trigger: 0.198 - 0.200, 0.281 - 0.285 Hammer: 0.199 - 0.200, 0.279 - 0.281 RECEIVER #2 Trigger: 0.199 - 0.201, 0.279 - 0.282 Hammer: 0.200 - 0.202, 0.279 - 0.280 RECEIVER #3 Trigger: 0.199 - 0.203, 0.279 - 0.281 Hammer: 0.201 - 0.203, 0.278 - 0.279 RECEIVER #4 Trigger: 0.199 - 0.199, 0.284 - 0.286 Hammer: 0.199 - 0.200, 0.280 - 0.281 I didn't intend to hijack this thread - I just wanted to mention this info so that you may consider this for inclusion into your receiver checkouts prior to building. |
| i have 20 years experence as a springmaker. protoing flat & round wire springs and custom metal parts. warpage is a common task for us! this is how we deal with it . stress relieve 1hr.@ 450 deg. in a streightening jig. a block of mild steel milled to the correct width for your ak rec. with 2 plates clamped to the outside fixing the block within. this may correct slight twist. or send it back! they will help if its way off. you can try anyway. don' t let the heat scare you.proper heat treating calls for a drawing temp. in some cases 900 deg. +. this is how you get the final hardness. this may help. good luck! OTTO |
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OK so it took me an extra day to get hold of Jimmy and then an extra day after that to get around to posting again. Sorry for the delay. I will give Jimmy credit, he was willing to make good on it. I'm going to have them swap the unbuilt receiver, but not going to disassemble the PMKMS to swap that one. But he was willing to swap it. So + points for Global. By the way they simply crush the receivers they catch as warped and don't attempt to straighten them. |
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