solide one piece cylinder and head
 

I think I am losing pressure in the cylinder. I have a v3 gearbox with a m90 spring and barely get 250 fps.
I saw a solide one piece cylinder and head from SHS from a supplier and was wandering if it was a god idea.
If someone as some feedback on this (good or bad) let me now.

It's bad idea due to the different tolerances between mechboxes.

If you're sealing your cylinder and cylinder head properly you shouldn't be getting leaks there anyway.

Sometimes on cheap plastic cylinder heads, the nozzle and the housing aren't secured and caused leaks. Best is to get a solid one piece unit with the nozzle milled with the housing. Most metal ones are so just get those. Make sure to get one with double o-rings for a better seal. Like stealth said, a cylinder and head as one piece won't work with all gearboxes due to difference in tolerances.

so i am better with something like:
Modify Enhanced Cylinder Head - V3 (Except AUG)
and keeping my original cylinder

just put some teflon tape around the cylinder head
cylinder/head seal is easy to test: mount the two together, block the nozzle with your finger and blow in it.Teflon tape around the base of the head or under the O-ring should fix that easily.
in my experience expensive cylinder heads are not required unless the stock one you have is extremely crappy...

I use the one piece cylinder/cylinder head from SHS in my ICS M4 and have had great results. But I agree with what Stealth said, they may not be a good fit for every mechbox due to variations in tolerances. It shouldn't be too difficult to get a good seal with a seperate cylinder/cylinder head as long as the cylinder head is decent quality. Ones with 2 o-rings are best, and Teflon tape around the cylinder head can help too.

I guess this tread should be more either a newbe or doctor seccion...
Ok, I check the nozzle/cylinder head: no leak
put teflon around cylinder head to joint with cylinder, seal look's good.
if I block nozzle with my finguer, am-I suppose to be able to push in the piston all the ways with no resistance?

Yes and no.
The ideal seal is one that seals when you're moving the piston at a relatively high speed.
If the piston o-ring seal is too tight, piston introduces excess drag, losing FPS.

Thanks, it make sense.
So instead of pushing, I drop the piston in the cylinder while blocking the nozzle and it did ''slow''.
Th o-ring is not cracked and doesn't show any flat spot, so I guess it is still good.

Also note that the seal is achieved when the tappet plate has moved the nozzle's base close to the front of the nozzle. It's very difficult to stage this by hand, since as John said you have to be moving your piston at a high speed to simulate the expansion of the main o-ring. If you have a nice vice , you may be able to secure your gearbox and cylinder such that you can hold the piston with your left hand and the end of the barrel with the other hand, with a piece of loose tissue near the hopup feeding tube, and test compression that way... But it's usually overkill to do this kind of testing.

The reality of airsoft manufacturing and inter-brand tolerances is such that you are going to occasionally have to experiment to find the best match between parts. A lot of guys in airsoft trot out the old nonsense like "matching brands is the best way to go", which ignores that a lot of stock parts (matched by brand) are often inadequately matched to each other or sub-optimally designed in the first place.

The only way to achieve really good builds with excellent compression is to study where leaks happen and have many slightly different spare parts and bits in your workshop to iterate and continuously test what improves or degrades a given compression solution.

Over time you'll be surprised how much variance there is.. Some nozzles bind on the cylinder head because they're too tight, or leak because they're too loose. Some are loose on their tappet plates. Some have the wrong taper shape on the end. Some are too long or too short, leading to terrible feeding or no compression. There are maxima and minima in every mating or interaction between parts in your system.

And some just won't work no matter how awesome they seem to be because the BBs from the magazine are preventing them from returning to the front fast enough (leading to the "cut 2 or 3 coils off the tappet spring" fix).