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Shots on semi sound different from one another (SR10)


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#1 randallh1989

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Posted 10 February 2014 - 03:13 PM

Just got an SR-10 a few weeks ago.  I notice that about half the time I am firing on semi-auto, one shot will sound quieter than the next, then a normal sounding one again, then a quiet one again - each shot appears to move the same speed and distance - what is the cause?  It almost sounds like one shot got a full effort from the gearbox, and the next shot was kind of half-assed.  I'm not good with technical stuff at all and wouldn't feel comfortable opening up the gearbox.  I have no idea what makes the problem start/stop, it seems random and doesn't happen when I fire full auto.

Running 11.1v 20c Lipo (I know I shouldn't go over 15c..  Could this cause the problem?)

#2 vanevery

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Posted 10 February 2014 - 03:42 PM

Need more info.

Sound is:
- from barrel?
- from gearbox?
- from motor?
Combination of the above?

What magazines are you using?
What BB's are you using?
Have you cleaned you Inner barrel?

#3 Jesse Hammil

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Posted 11 February 2014 - 07:34 AM

It sounds like over spin. Are you running a Mosfet? Stock spring?

What's happening is your spring compresses,  shoots (uncompresses) and then compresses a little more. So when thus happens,  and you pull trigger,  the spring  is already partly pulled. You don't hear the great working  to pull the spring back. This is because your motor takes an amount of time to stop and the 11.1v lipo is so strong it takes longer for your motor to stop.


As far as using a 20c battery,  you can use it as long as it's in spec.  People on here run some out of spec batteries and have no trouble.

C rating * MaH /100 = Amp
I rthink you want to stay 28 or under to stay in spec.

I have over spin in my ris and commando from running a 11.1v lipo. I'm building an active braking mosfet to fix it.  Also others have said a heavier spring or low torque motors will remedy it as well.

Edited by Jesse Hammil, 11 February 2014 - 07:42 AM.


#4 Chuck S

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Posted 11 February 2014 - 03:18 PM

Your battery is fine.  The C-rating is the amperage rate the battery can safely discharge or charge, nothing more.  Draw or charge at too high a current and you'll damage the battery.  Got diddley to do with the gun any more than charging your cell phone on your car battery rated at 700 cold cranking amps will hurt your cell phone or try to dump 700 amps into it!  :)  There's a fuse inside that limits the AEG's battery draw.

The higher the voltage the faster the motor spins and it can outrun the mechanicals inside and move the piston partially to the rear again.  Will sound different.  Cyclic rate is based on how fast the motor spins.

An AEG should shoot the same velocity and distance no matter how far back the piston starts before the motor draws it back, it's all about the forward motion of the piston from the release point.  I always thought that at least from a theoretical position an AEG would be more effective with a mechanical sear to release the already compressed spring -- like spring guns only using the motor to recock the gun after firing each shot rather than before.

-- Chuck

Edited by Chuck S, 11 February 2014 - 03:19 PM.


#5 randallh1989

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Posted 15 February 2014 - 08:27 PM

Thanks, guys!  Maybe I should run a 7.4?  ROF isn't really a priority of mine anyway.

#6 Jesse Hammil

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Posted 15 February 2014 - 09:18 PM

If you don't care about rof, and your not trying to pull a heavy spring,  I would say yes.

#7 niko_gpsy

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Posted 17 February 2014 - 04:16 AM

Without the help of a mosfet with active braking your piston will not always completely reset after each shot when firing in semi.  So a shot that occurs when the piston is half cocked position will sound quieter and "shorter" than a shot fired when the piston in fully reset.  It's not necessarily a problem and many guns do this no matter what brand.  I really wouldn't worry about it.




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