Best bucking and nub for CYMA platinum ddkm18 (m4)

[tk2010]

Nephew just bought this, had a terrible air seal on stock bucking .74j and +/-15/20fps changed it out to a purple prommy and a bit of PTFE and it's gone to 1.07 @ +/- 1fps ?

 

But it's pulling right.

 

Anyone with experience please got an idea for the best bucking without having to file down the window (not my gun don't wanna risk breaking anything)

 

Please let me know 

[Lozart]

First things first - check that it's actually straight in the hop unit.

[tk2010]

44 minutes ago, Lozart said:

First things first - check that it's actually straight in the hop unit.

Will do 

[_K4MF_]

Well I don't have the M4, but I've got the Cyma Platinum C.041G MP5K and I switched the bucking for maple leaf macaron, works like a dream. 

[The_Lord_Poncho]

17 hours ago, Lozart said:

First things first - check that it's actually straight in the hop unit.

Almost certainly this - you mention you used PTFE - in the past, I have slightly twisted the bucking in the barrel window by pulling it off centre when wrapping the PTFE tape... Presume that you have also given the barrel a good clean to discount that, and are ensuring that the gun is absolutely vertical when you shoot it.

[Sewdhull]

The barrel in my Cyma can rotate a bit in the hop unit, which rotates the bucking.

I'm with the check it's straight in the hop unit gang...