New cylinder doesnt fit!

I have tried to replace the cylinder and head but they are about 1ml too long…
any tips on how to fix this??

You will need to grind or file it down :frowning:
Do it at the cylinder head end and be sure to debur it afterwards.
It’s funny because some Gen9 and 10’s take different lengths

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OK, if i file it down a bit too far will that matter?

Not if it’s only a little, just go slow and get it right :+1:

ok, will do, thanks a lot

Yep had similar issue
Multi colour cylinder 1 mm too short and allowed the cylinder head to come out slightly and loose pressure and fps. It was a new part I got with an upgrade kit! I ended up getting a stainless replacement one and it worked perfectimage

so if i had your multi color cylinder with my head, it may end up being the right length???:thinking::rofl:

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I have the same blaster and same part and mines about 1mm short too

Get some wet and dry sandpaper (400 should be ok). Lay the paper flat on a bench with a couple of drops of vegetable oil on it. Stand the cylinder up and rub it in a circular motion in the sandpaper. You’ll get a nice surface grind and keep it even around the cylinder rim.

Feel free to use other lubricants (wd40 even water), but I find cheap veg oil the best because it doesn’t smell and you don’t have to keep applying more like you do with water.


Did u still use urs?

I think the cylinder is the right length but the head is too long… so would it matter if i made the cylinder shorter and left the head?

You are better shortening down the cylinder and not the head. The length of the head is what gives you your tappet travel to suck up the balls.

OK, but what do you mean by suck up the balls??

@Calcifer will be along shortly and show you :see_no_evil:


The length of the tappet travel is governed by the length of the head. Most gel blasters require more than airs0ft requires because our balls are 7.2 and not 6mm.
My rule is always use a gel blaster head and use a tappet plate with the the extended cam lobe which gives you the correct timing for the bigger balls.

It’s not the cylinder that’s too long or short normally, 72mm is what they should be, it seems JM gen9 and gen10 cases vary quite a bit so some people have problems.
I have had to shorten a few cylinders.

It should be fine as long as it’s not very much

That looks fine, not a problem at all except I like them the other way round :grin: