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LM4 PMAG Repair

LM4 PMAG O-ring repair

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#1 General Pickle

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Posted 05 February 2013 - 12:50 PM

Hello fellow LM4 users! I must say this gun and system is quite impressive so far, as the design is actually quite intuitive for disassembly if I do say so myself. My buddy lent me a few of his LM4 PMAG's for a while, basically until I can find my own to buy, and in the meantime I'll fix all of his leaky mags for him. Sweet deal right? Anyway, I found the leaky spot; the "Magazine Inner Post" part #LM4 PTS-13 is the location, however I feel it is safe to assume that the leak is due to part #LM4 PTS-22, the o-rings that are supposed to seal this breach in the body of the magazine, which seem to have failed.

Sometime this week or next week I will have the tools needed to get inside this part of the magazine and I will do the repairs if possible and/or take a measurement of #LM4 PTS-22 and see if we can get a solid economical replacement o-ring, similar to the fill valve o-rings I found earlier(sold on big sites for $0.90 each, bulk ordered for $0.05 each). I didn't see a thread about this particular issue yet so I thought I'd go ahead and do my best to offer an alternative solution for this seemingly common leak spot. Happy airsofting!

#2 General Pickle

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Posted 07 February 2013 - 08:30 PM

Alright, the repair was smooth once I had the pin punches and soft hammer to do the job. Just pull the inner post out, clean the o-rings, flip them around to a non ripped side, reassemble, bam! All done! I think the screws holding the inner post in place were getting uneven too, so perhaps that was causing one side to have a compromised seal? Anyway, it holds propane like a champ now!

These are the dimensions I pulled from part #LM4 PTS-22: OD=17/64" ID=5/32" CS=0.056", so the closest size I could find so far was AS568 size -007(OD=18/64" ID=5/32" CS=1/16"). Perhaps this is a viable replacement for the o-ring in question? If I need to test this myself I will and you will be the first to know!





Also tagged with one or more of these keywords: LM4, PMAG, O-ring, repair

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