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Old 02-24-2005, 06:30 PM   #1
 
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Gas Piston and Piston Nut general questions

Still learning by inspection as I am in the city and not learning by shooting ... Trying to figure out the gas piston and nut assembly. Should there be play (any movement) in the piston while the gun is at rest? Logic would tell me that you should be able to move the piston manually. This piston is completely frozen and there is far more carbon buildup on the piston than I think there should be for the 50 rounds I have put through a new rifle. The nut is seated deep in the housing and is visible through the gas port. Is this as it should be? I appreciate your comments and thank you for sharing your knowledge.
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Old 02-24-2005, 06:55 PM   #2
 
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It the "piston" should be somewhat "loose" the nut should be tight but if you have fired it and no function problem do not touch it leave it. sometime buildup will make it sticky a good soak in gun solvent will help.
Bruce
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Old 02-24-2005, 08:35 PM   #3
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No, if this is the AO you have been having problems with, it should move freely, and this could be your binding problem causing it to not go into battery. As Bruce stated, try soaking the entire gas cylinder in a bowl of bore cleaner (well ventilated, NOT in your wifes good bowl) overnight, and then check movement with a magnet if you have one. Ideally, it should move freely when you tilt the barrel up and down. Protrusion into the drilling hole is normal, as the nut seals the hole they made while drilling the barrel.
I think I have a picture of one showing how deeply seated it is, I'll look for it. This is the best one I have at the moment.
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File Type: jpg gaspiston WRA 5.6 mill.jpg (52.1 KB, 265 views)
 
 
Old 02-25-2005, 01:40 AM   #4
 
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Quick and dirty. Open the slide and lock it, plug the chamber with your finger, tilt the barrel up, suck in and blow out on the end of the barrel. You should hear and feel the gas plug move back and forth.
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Old 02-25-2005, 04:08 AM   #5
 
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Yes, this is the problem child AO. I have a return authorization from Kahr/AO but am trying not to go that route. I think I have found my culprit. THANK YOU ALL for all the prompt replies. I will be trying the "1st Maine Method" on the rifle when I get home from work tonight. I will let you know if I confirm my thoughts!
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Old 02-25-2005, 04:58 PM   #6
 
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Hope this thread is picked back up - Here are findings:
I performed the "1st Maine Method" on the M1 and I feel so cheap ... After sucking and blowing on the muzzle while blocking the chamber with a finger, my (our) fears were confirmed. That gas piston is FROZEN. It is petrified. It is incapable of movement, much like a Nowegian Blue. I replaced the original slide and noted much battering of the interior of the slide by the frozen gas piston. Scalloped out a small spot in fact. A gas piston nut wrench and new nut have been ordered. I believe I may polish the piston itself with some fine grit abrasive as needed. More as the story develops -
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Old 02-25-2005, 07:58 PM   #7
 
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"its not dead its sleeping" LOL
Bruce
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Old 02-25-2005, 08:18 PM   #8
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I really recommend soaking the piston with a good solvent for at least three consecutive days to see if that will loosen it up. Since the nut is staked, I don't recommend removing it unless you have a way of chasing the threads before putting the nut back in. Normally you do not need to remove the piston nut. Solvent usually works.
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Old 02-25-2005, 11:45 PM   #9
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Ditto Jimb, you've now heard from the two gunsmiths on this forum. WE don't like removing them, you shouldn't unless you are very experienced and have extra nuts along with the tool to chase the threads. I don't know how many nuts I ruined before following my own advice! Soaking has worked 100% of the time for me, try that first, it's basically free. Restaking isn't as easy as it looks either.
 
Old 02-26-2005, 03:27 AM   #10
 
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Roger. I will soak first. Gun show in town today and I need bore solvent anyhow. I truly appreciate all the helpful information I have received here.
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Old 02-26-2005, 04:14 AM   #11
 
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I go back to what Bruce initially said/indicated. When you fire your Carbine you're dealing with 40,000 psi, which is quite a bit more pressure than "trying to move the piston back and forth by blowing and sucking on it, etc".

Does your Carbine work when you shoot it? That's the real "test"---otherwise, I wouldn't necessarily suggest screwing around with it----leave it alone.

Otherwise, I agree realtive to not taking the piston out---at least not as a 'first remedy'.

As far as the 'gouges' in the slide, that may be normal---the AO slides are, after all, investment cast parts. The thing is, if your piston was actually stuck "out" such that it was actually gouging the slide, your bolt wouldn't shut all the way----and, that's not my impression of whats going on with your Carbine. Again, go shoot it----quite trying to find a solution to what may well be a non-existant problem.
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Old 02-26-2005, 05:25 AM   #12
 
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Definitely a problem with the rifle, not just playing here. Failure to go into battery on second round with a new rifle. Numerous failures to go into battery in first 50 rounds fired when using different magazines. Action cycles fine by hand and when using dummy rounds to feed/test bolt and extraction. Others have commented that perhaps the slide not travelling all the way home/forward may be related to the gas systm, this seems to be the case on this rifle. Sorry, we have jumped threads here and not all this information may have been apparent or known. Best Regards -
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Old 02-26-2005, 06:36 AM   #13
 
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Okay, I understand. Being a new Carbine, what are the chances that you can just send it back for repair?
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Old 02-26-2005, 08:27 AM   #14
 
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Boone: Hope I didn't lead you to believe the "quick and dirty" check was a final diagnostic method. I just use it to check the freeness of the gas plug, and get looking in the right direction for further troubleshooting. I mentioned in the earlier thread that neither of my AO gas plug nuts were staked, thus allowing the nuts to back off after firing. Did you happen to notice if your's was staked? My carbines are in the 700 & 800 serial# range. Don't know if they corrected this oversight in their assembly yet.
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Old 02-26-2005, 10:13 AM   #15
 
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1st Maine, this rifle is low 500's. The nut is not staked. For a piston assembly that should have play in it, this one has none and seems unusually "elongated" in that it protrudes more than photos I have seen. I have it soaking as we speak. I had commented on one of the threads that the piston seemed unusually fouled for the 50 rounds I put through it. Heavy, baked on fouling. My barrel was unusually dirty from the factory as well. I do not know if the factory cleans after test firing or not. Had I not seen the rifle come out of sealed box in wrap, I would have expcted it to be used. When I talk about barrel fouling, I am talking on the order of my CMP Garand, really pretty dirty and not just grease/preservative but a lot of fine particulate carbon. I did not inspect the piston prior to initial firing.
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Old 02-26-2005, 11:04 AM   #16
 
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Both my carbines came from AO with the same fouling you describe. I had spoken with Stefan Dorman at AO about it. He said they test fire each rifle at the factory, but only put a couple of patches through them before oiling and packing. The factory service folks have been super by the way. The last time I had to send one of the rifles back, I had it back in about 10 days.
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Old 02-26-2005, 11:13 AM   #17
 
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Correction - The nut WAS staked and has rolled out of its stake spot so that the two indents are no longer lined up. The staking was not very solid and was unnoticed since the marks were small and not together.
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Old 02-27-2005, 06:35 AM   #18
 
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For anyone intrested and following the thread, I located the following pertinent info in Carbine, Cal 30, M1 Technical Bulletin 23-7-1 :


31. PREPARATORY TO FIRING. --
Before firing, the following procedure will be observed to assure the efficient functioning of the carbine. f. Lightly lubricate the following points, with a drop of oil from oiler rod. (items 1-8 omitted)
(9) Piston shank
32. AFTER FIRING. --
(1) Gas cylinder and piston. -- After extensive firing, remove the piston. Clean out all excess carbon from gas cylinder and from head of piston. Care should be used when removing carbon not to scratch gas cylinder or piston unnecessarily. Check gas port in barrel after cleaning to make sure it is free, a test piston for freedom of action in gas cylinder and through piston nut when reassembled. In rearward position, piston should protrude about inch.
33. ON THE RANGE OR IN THE FIELD. --
f. Remove the carbon the gas cylinder and the piston head when necessary. (Sluggish action of carbine may indicate clogged piston).
g. In general, it should not be necessary to remove any of the parts of the carbine in the field for cleaning, except to dismount the barrel, receiver and trigger housing group from the stock. Due to position of gas port, the gas cylinder and piston should not require cleaning often.

38. FIELD INSPECTION.
(8 Piston. -- Piston may reciprocate sluggishly due to excess carbon on piston head or in gas cylinder. Piston should reciprocate in gas cylinder and through piston nut (about inch) when barrel is shaken. The piston nut should be kept tight at all times.
NOTE: If piston becomes "frozen" in gas cylinder, due to rust or carbon, soak with penetrating oil for about one hour, and then work loose and shake out. Loosening may be helped by working with a prick punch or similar tool through gas port hole in outside of gas cylinder. When removed, piston and gas cylinder should be thoroughly cleaned, oiled and examined for burs, and gas port examined for foreign matter.
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Old 02-27-2005, 01:48 PM   #19
 
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Frozen Gas Piston - Wrap up

Problem seemingly solved. The soaking of the nut/piston assembly in bore solvent and then penetrating oil did no good. Piston was still solid. Borrowed a piston nut wrench from a retired Army Colonel and backed the nut out. Rangers lead the way! Easy operation after all the soaking, no stripped threads. The piston was frozen in the gas system block. I plucked the piston out with needle nose pliers being careful not to mar the finish. I then began to remove a little of the finish off the edges of the piston head, continually checking its seat and fit in the gas system. After initial stock was removed with 400 grit I moved to bore paste for a final polish. I did a test fit of the nut and piston so that it was just passing Wayne's magnet test to get the piston to move in and out. I dropped a few drops of loctite blue on the nut and set it with the wrench. I have not yet test fired, but at least I know the piston is now moving as it should. As an aside, I would say that I owned and fired hundreds of rounds through a second hand Universal M1 and never even knew the gas piston existed until this new AO carbine.
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Old 02-27-2005, 08:31 PM   #20
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Happy to hear the good news! Just so you know, many Universals have a pinned type of gas piston, and don't have the removable nut like a USGI Carbine (I went and looked at my Universal to be sure of this). The piston actually seals at the rear where it's bevelled, against the corresponding bevel of the nut, and the "shank" is just for driving the slide. You could polish this part all day long and not hurt the gas seal, so you did good. Most of my pistons are pretty sloppy side to side, but seal very well on the bevel where it's important.
By the way, many don't know there were two different nuts used, the newer version being counterbored 0.030 inches deep, which allows more power. This nut was recommended for all M2 Carbines.
 
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