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mcguyver · May 21st, 2006, 10:17

If you use a "windowless" mechbox in a gun with a full or over-capacity cylinder (no holes in it), there is a good chance your FPS will go right into the toilet. This is because on the "intake" stroke of the piston, the inrush of air in to cylinder is impeded by the lack of holes in the mechbox to allow for this volume to enter the mechbox and be drawn into the cylinder.

I did an ICS MP5 with full capacity cylinder and M4 length inner barrel. With a 110% spring, the FPS was about 240. I changed the cylinder to a 4/5 M4 cylinder from a Marui and the FPS jumped back up to 335. ICS uses a "windowless" mechbox as well.

May 21st, 2006, 10:17	#5
mcguyver Trader rating Join Date: Aug 2005 Location: Northern Alberta	If you use a "windowless" mechbox in a gun with a full or over-capacity cylinder (no holes in it), there is a good chance your FPS will go right into the toilet. This is because on the "intake" stroke of the piston, the inrush of air in to cylinder is impeded by the lack of holes in the mechbox to allow for this volume to enter the mechbox and be drawn into the cylinder. I did an ICS MP5 with full capacity cylinder and M4 length inner barrel. With a 110% spring, the FPS was about 240. I changed the cylinder to a 4/5 M4 cylinder from a Marui and the FPS jumped back up to 335. ICS uses a "windowless" mechbox as well. __________________ Age verifier Northern Alberta Democracy is two wolves and a sheep discussing what's for dinner. Freedom is the wolves limping away while the sheep reloads. Never confuse freedom with democracy.