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Failure-to-Fire & Inconsistent Firing

LM4 PTR Hop Up Hop Up Bucking Accuracy Inconsistency

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#1 I PH34R N0 1

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Posted 26 May 2013 - 03:08 PM

Hello,

A little more than a month ago I have noticed that malfunctions and failures-to-fire have been very common. I can fire two or three rounds and can see the BB travel for about 300ft with a slight Hop Up adjustment. However, when I fire again, no BB exits the barrel. Only when I invert the gun does the BB fall out of the barrel. I have field stripped the gun and set the Hop Up to its default location. It appears as though the Hop Up bucking is split down the center and is obviously obstructing the barrel. Is this a simple replacement of the Bucking? I have not made any internal modifcations whatsoever and I clean it often. I am using standard USGI style magazines with Goldenball ProSlick Competition-Spec Ultra High-Grade 0.25g BBs and Elite Force Fuel and Airsplat Green Gas Propellants. I use Hoppe's No. 9 High Viscosity and Penetration Lubricating Oil for Firearms when cleaning the gun. My guess is that the Bucking was very cold and weak when fired as the package was covered in two feet of snow when I recieved it and cracked due to the high pressures.
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#2 Jatodude

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Posted 26 May 2013 - 09:40 PM

Your hop up looks perfect to me, other than the fins are supposed to be a little lop-sided. I can't imagine off the top of my head any way that this could be happening. Firing, then not firing so the BB drops out of barrel? Do you have your piston anti-rotation piece in the bolt?
Perhaps what you're describing is compression loss. The piston o-ring (part 191 I believe) may have gone bad. Coupled with the cold weather of Wisconsin, it may be producing these results. It's hard to say though with minimal information about the issue.

Edit: Fins are NOT supposed to be lop-sided.

Edited by Jatodude, 28 May 2013 - 12:37 PM.


#3 I PH34R N0 1

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Posted 27 May 2013 - 07:25 AM

I checked the piston O-Ring and it looks perfectly okay. I made sure to lubricate it as well. I was firing it on a 85F day and even then my first shot failed to exit the barrel so the temperature may not be a factor. Any other ideas?

Edited by I PH34R N0 1, 27 May 2013 - 07:26 AM.


#4 netpoc

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Posted 27 May 2013 - 08:01 AM

Is that Hoppes oil corrosive to rubber? As in o-rings? Not something I'd recommend to use. Just wipe your gun clean with a dry clean rag and relube with silicone where needed.
As for the firing problem replace your hop up bucking, if your piston o-ring is okay.

Edited by netpoc, 27 May 2013 - 08:05 AM.


#5 I PH34R N0 1

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Posted 27 May 2013 - 11:15 AM

The oil is non-corrosive to all materials. I did a 10 round firing test into multiple layers of styrofoam at a zero degree angle and only seven shots hit. The other three BBs fell out of the barrel when it was aimed at the ground. I inspected every BB and noticed that only those that failed to fire had deep gashes and cuts in them: something that wasn't there before. Could it be a Piston problem? As the BBs are improperly loading and double feeding? Or could I have reassembled my magazine improperly as I have taken it apart to tighten the Release Valve with a Valve key? It seems as though the BBs only fall out of the barrel when it is pointed at the ground.

I will still conduct more tests.

#6 -wigs-

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Posted 27 May 2013 - 04:51 PM

Idk what the penetrating agent is in that oil but since it's most likely there to eat away carbon and other build up from rs guns I wouldn't recomend it in the lm4

#7 I PH34R N0 1

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Posted 27 May 2013 - 05:10 PM

I believe I fixed my problem. I ran some more trials after I reassembled the magazine and thoroughly cleaned the bore and I've had no more issues firing both semi and fully automatic. Also, the Hoppes oil is not a bore cleaner which is corrosive to nickel and carbon and it states that it is "For all mechanisms". I've used it for five months and it still provides great lubrication on all O-rings. Anyway, thank you to everyone who offered advice and suggestions. If I have any other issues I know just where to get help.





Also tagged with one or more of these keywords: LM4 PTR, Hop Up, Hop Up Bucking, Accuracy, Inconsistency

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