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LM4 PTS: Consistency issues

LM4 consistency propane hopup

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#1 General Pickle

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Posted 09 March 2013 - 07:19 PM

Hey guys, I had my LM4 out today and it ran much better now that it's not 20 degrees outside, but I was seeing an inconsistency in accuracy; sometimes it was flat out BEAUTIFUL accuracy and range, reaching out to 200ft or more dead on to my sights (using .30g Biovals, fyi), but then without any changes it would fire a few rounds or even a whole mag at 70ft or so, then somewhere down the line the amazing range and accuracy comes back like nothing ever happened. My hop up setting does not affect how often this happens, however it seems that the hopup is still effective when it actually is getting the good range.Could this be a hopup issue? Maybe the barrel is not secure? Perhaps lube got into the hop or something? I'm running propane dry with Bioval .30g's in PMags, all stock internals, using FrogLube as a lubricant in all my essential parts (BCG, charging handle, nozzle oring). Any ideas? Thanks!

#2 samtheman

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Posted 10 March 2013 - 04:52 PM

I would replace the o ring on the back of your nozzle to the HFT green oring that can be found at harbor freight. With the replacement oring, fps and accuracy inconsistency is dropped quite a bit and for cheap, so I recommend giving that a try.

#3 General Pickle

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Posted 10 March 2013 - 05:21 PM

Has anyone found a way to get those o-rings outside of the 205 set? I'd be happy to try it but that leaves me with about 200 useless o-rings. I hear the Danco #10 can help but I've also heard it doesn't work for some people. Maybe I ought to just suck it up and buy the giant set?

#4 BeachEMT

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Posted 10 March 2013 - 05:37 PM

I have also heard that frog lube might be too viscous. Since it's designed for higher temp environments, it's not as liquid as silicone oil at room temp.

#5 akiraspeedstar

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Posted 10 March 2013 - 05:55 PM

I don't recommend FrogLube for the piston o-ring though its great for the rest of the gun.

#6 General Pickle

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Posted 10 March 2013 - 07:57 PM

Ok, I'll see what I can do by just changing my lubrication methods first, then if that doesn't work I'll see about those o-rings. Thanks guys!

#7 Chuck S

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Posted 11 March 2013 - 05:34 AM

You can pick up the Danco #10 o-rings at Home Depot at lunch today and see how they work tonight.

The silicone oil I have is pretty thick in freezing temperatures.  Frog Lube CLP (not the grease or pastge) should be fine when used sparingly.  They claim it's (1) food grade and (2) and:

Quote

Since FrogLube is non-corrosive to plastics and rubber, it is the preferred lubricant and preservative for O-rings, non-ferrous and rubber parts. FrogLube will actually condition O-rings and improve compressed air and pressure tank retention properties.
-- Chuck

#8 JonathanNCP

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Posted 11 March 2013 - 05:49 AM

Question: Does it fire about 7 shots perfectly (firing rapidly) than 3-4 like there isnt any hopup? Mine has been doing that all winter, but as soon as one shot comes out low I wait about 4-5 seconds and all is good. Its like liquid propane got on the hop up and needs to dry up before it starts shooting good again. I was curious and tried my buddies unmodified bolt (my rocket valve was shaved) and it happens less frequently, about after 20 rapid shots, but it still happens. I dont remember encountering this in the summer but I modified my rocket valve in the fall so two things have changed since then (temperature and shaving the valve), so I am anxious for the warm weather to see if the problem goes away.
I dont know if that is your problem, but its something I have enocuntered.

#9 General Pickle

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Posted 05 May 2013 - 09:59 PM

I think my issue was that I caked on too much Froglube, causing a nozzle freeze up when using rapid fire. Thinner lube coating: check. Now the hop up inconsistency I feel is just a bad bucking problem, since the gas is clearly getting through the gun just fine. Soon I'll have an EVO II kit installed and we'll see what happens then. I noticed that my stock bucking looks kinda worn out and just not great in general. This platform is damn cool, it just has some strange quirks in the design that I would have expected to be worked out by now. More updates to come as these things are taken care of.





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