Cylinder SR25 - LONG [GUARDER]

In a DMR, you're looking for the maximum amount of cylinder volume in order to have a good cylinder:barrel ratio of at least 2:1.

The full length guarder SR25 cylinder (made for sector gears with 19tooth) provides just that.
The cylinder itself is very well finnished which means the piston will easily glide through it and you'll not lose FPS because of the piston being dragged over a rough surface. This is aided even more when using some silicone oil.

Using this in combination with a Guarder V2 cylinder head and a fitting piston head (like guarder, but others fit as well) gives perfect airseal.
This, again, is aided by applying silicone oil to the piston head o-ring.

Hint: to add to perfect airseal, a nozzle with 2 o-rings (taiwangun sells my favorite: EPES) in the relevant length for your gun is necesarry.

All these things combined, my SR25 with a 510mm barrel and this cylinder + head + nozzle combination gives me a Cylinder:barrel ratio of around 2:1 which is perfectly suited to hopping .4g BBs (with the corresponding HopUp Setup, of course).