Padrooga 55 Posted May 30, 2014 Report Share Posted May 30, 2014 (edited) Hello all. I've been experiencing some piston 'scraping' for lack of a better description; when racking the handle the piston seems to scrape along the inside of the gas tube, making quite an unpleasant noise. This began after the second range day with it. I've had the rifle for a while (forgot to mention the issue long ago), and it doesn't seem to affect function at all, but I was wondering if anyone knew of a fix/possible cause. The rifle in question is a Century conversion that I've been modifying. Cheers! Edited May 30, 2014 by Padrooga Quote Link to post Share on other sites
Shandlanos 1,470 Posted May 30, 2014 Report Share Posted May 30, 2014 The piston is scraping against the inside of the tube?If that's the case, it probably wasn't correctly installed in the carrier - or the rear sight block or gas block is canted, so the gas tube isn't straight. Quote Link to post Share on other sites
Padrooga 55 Posted May 30, 2014 Author Report Share Posted May 30, 2014 Piston, thank you. Slip in terminology. ^___^ Yes, it appears to be. That was my guess. Could that be due to an error during conversion, or is it more likely a plant issue? Quote Link to post Share on other sites
Shandlanos 1,470 Posted May 30, 2014 Report Share Posted May 30, 2014 Unless you installed a replacement piston, or for some reason were messing around with the gas block or rear sight block with substantial force - that's a factory issue. As a century conversion - it's almost assuredly a century issue. Best guess is an improperly installed piston. You could send it to any gunsmith on this forum to fix it - or you could try to do it yourself. The gas piston is blind-pinned, so it can be a little difficult to find the pin to remove it. I've never done it, and if you plan to do it yourself, I would highly recommend finding a decent tutorial video.You might contact century to see if they can fix it - but they'll probably want you to send the whole rifle. Quote Link to post Share on other sites
Padrooga 55 Posted May 30, 2014 Author Report Share Posted May 30, 2014 Damn. No replacement/messing with substantial force of the aforementioned components. Thanks for the input! Guess I'll just endure the scraping. I'm still curious as to why I wouldn't have noticed it on the first run...probably just didn't look for it. Quote Link to post Share on other sites
Shandlanos 1,470 Posted May 30, 2014 Report Share Posted May 30, 2014 By all means, wait for a few more responses - I'm not a professional gunsmith, just a hobbyist with a moderate collection of AK-pattern rifles and shotguns. Someone else may have insight that I do not. Quote Link to post Share on other sites
Padrooga 55 Posted May 30, 2014 Author Report Share Posted May 30, 2014 Of course. I appreciate all of the quick and informative responses I've received on this forum, since I myself have little experience with this stuff. I probably know my way around an AK-pattern more than your average female (or male, for that matter, lol...), but I want to learn all I can in order to be self-sufficient. My aspiration is to go to one of Fuller's workshops in the future...that guy is just awesome. Quote Link to post Share on other sites
Inebriated 31 Posted May 30, 2014 Report Share Posted May 30, 2014 (edited) Not trying to insult your intelligence, I promise , but have you stripped it down and carefully reassembled it? I can't imagine you installed anything incorrectly, but it's worth checking. Also, can you tell us where in the gas tube it seems to rub? Right before the piston enters the gas block, halfway through, the whole way through, etc? Are there any burrs on the edge of the gas block, where the piston rides up? Are there any burs on the piston itself? And lastly have you checked to see if your gas block and rear sight block are aligned? To check the gas block, remove the handguard, and sit rifle down on a level surface. Sit it so that it's resting on the bottom of the receiver (it helps to have it balanced there, on a block of wood or something). Put two square objects (carpenter's squares, cereal boxes, anything... just need to be square) on either side of the gas block, and look at it from the front or back... you should be able to see if it's centered or canted to one side. To check the rear sight block, just sit a level on your rear sight and check to see if it's canted. Edited May 30, 2014 by Inebriated Quote Link to post Share on other sites
Padrooga 55 Posted May 30, 2014 Author Report Share Posted May 30, 2014 No insult at all! Yes, I've stripped it down and re-assembled. I think that's one of the first things I try when troubleshooting most mechanical objects. ^___^ The piston seems to begin rubbing about a third of the way through. No burs on either mentioned area (from memory, but I'll have to inspect closer after work). Checking the gas block and rear sight block is something I haven't done yet! It may be a few days before I report the results; beginning of a long work week and all that. Thanks a lot for the suggestion and tutorial. Quote Link to post Share on other sites
BigChongus 765 Posted May 30, 2014 Report Share Posted May 30, 2014 Best case scenario would be a canted gas block, as that's a fairly easy fix. Quote Link to post Share on other sites
Matthew Hopkins 1,065 Posted May 30, 2014 Report Share Posted May 30, 2014 (edited) Best case scenario would be a canted gas block, as that's a fairly easy fix. yep, that's what that sounds like, and I'm betting there is no wobble to the gas piston that it should have. I have a SAR 3 with a slight cant to the gas block, and when CENTURY changed out the parts to US parts, they installed a US piston, but they tack welded the thing on the carrier so that it ridged, instead of it "hanging free" and finding it way to the gas block, it scraped the inside of the gas tube, and hit inside the gas block. seeing I bought the thing for way under 2 bills, NIB, I just said screw it. it finally worn itself a path and hasn't caused any problem since. that was my "easy fix" Edited May 30, 2014 by Matthew Hopkins 1 Quote Link to post Share on other sites
Padrooga 55 Posted May 31, 2014 Author Report Share Posted May 31, 2014 Oh Century. I suspected it may be such. I think in one of Polenar Tactical's videos I heard the same noise...I'll keep an update on the status. Quote Link to post Share on other sites
semper299 284 Posted June 5, 2014 Report Share Posted June 5, 2014 Not to sound dumb, but make sure the gas tube is pressed all the way down. Not likely your problem but doesn't hurt to check. Quote Link to post Share on other sites
Padrooga 55 Posted June 9, 2014 Author Report Share Posted June 9, 2014 Not to sound dumb, but make sure the gas tube is pressed all the way down. Not likely your problem but doesn't hurt to check. Hey thanks! I will check that out too. So far nothing seems to be canted, so I'm betting it's the piston. Put it through some paces the other day with no complaints (as usual) so this will probably go on the back burner for a while. Thanks all for the help and suggestions as usual. The internet may have its downfalls, but it's sure as hell good for learning and collaborative troubleshooting. Quote Link to post Share on other sites
SaigaKen 338 Posted June 9, 2014 Report Share Posted June 9, 2014 (edited) Do you know anyone with a like rifle? You could hand cycle your bolt\carrier through thier rifle and hand cycle thier bolt\carrier through your rifle to see if the problem is consistent in the mix\match........ Edited June 9, 2014 by Saiga Power Quote Link to post Share on other sites
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