It's completely normal for the nozzle to stop not fully forward, it's caused by overspin, overspin isn't necessarily a problem. Most gearboxes have some overspin, it's because of the inertia in the spinning gears. As long as it shoots and feeds normally it's nothing to worry about. FYI an SP120 spring is equivalent to an M130 and may damage the internal parts if the gearbox is stock, and there's a good chance it shoots over the FPS limit at most fields.

 

I'm just afraid that I'll get some air leak because of that, or damage spring, because it's not fully decompresed.
My field limit is 130m/s, so it's perefct spring for that.
What can it damage? Gears?

 

Slight overspin does not damage anything, and does not cause air leaks. Almost every gun will overspin to some degree. There is nothing to worry about. It is really only an issue if you are shooting more rounds after you let off the trigger (like shooting 2 rounds in semi auto), but other than that, it is completely fine. It will not wear out the spring having it lightly compressed either, and if it does then it was a poor quality spring to begin with.

 

As Lefse has said a bit of overspin is normal
by the time the sector gear engages the piston pickup tooth taking up spring tension
(slowing/stopping the whole drivechain)

By the time the 1st tooth of sector gear engages the the piston and begins to retract piston
The tappet/nozzle is about 75% retracted anyway

You get more overspin the faster you go and other factors like lighter springs etc....

A bit of overspin is nothing to worry about - if still paranoid about leaving gun pre-cocked shoot a few shots on 7.4v to park the gun without so much precocking

However if a gun is firing twice on semi then that is cause for concern as you may be approaching PME
But you get more overspin if other factors like tight trigger contacts, worn Cut Off Lever popping the trolley later/slower than usual etc.....

I'd worry if she starts double firing on semi, so on SP120/M130 you must be using 11.1v
don't use a crazy burst C rating and you should be ok

 

Thank you guys.
I don't want to make another topic, so gonna ask here.
What do you think or maybe someone is using rtv around cylinder head to get perfect compresion between cylinder and cylinder head?
So far I have used teflon tape, but after few games need to rewrap it again. Rtv make more sense, but I'm afraid that It will put more preasure to gear box. Any toughts?

 

RTV works well as a cylinder sealant. I use teflon tape most of the time, but I go crazy with it and have to really force the cylinder down on the head. Teflon tape makes it easier for me to take it back apart so I can check the sorbo pad for wear and tear and change it out when it does wear down. RTV does do a bit better of a job sealing it up, and is commonly used as well. Its just a preference thing on which you want to use.

 

Good air seal will not cause issues, unless you're having a BB jam in the hop-up or barrel, but in that case stuff break anyway. In most cases the cylinder head will fit snugly inside the cylinder and I just put some silicone oil on the o-rings and it'll give a 100% seal. Teflon tape should not get unwrapped between the cylinder head and cylinder unless it sits very loosely.

 

Thank you!