Technician1 Posted January 15, 2012 Posted January 15, 2012 HELP This is doing my head in now with the amount we have thrown at the gun Gearbox has all ultimate parts spring guide Cylinder Piston Cylinder head madbull m110 spring We built the gearbox and added tightbore barrel and one piece hop Fps around 280 ish Remove the front of the gun and replace with a tightbore barrel and hop from another m4 that fires at 370 fps, and the fps on the stubby raises to360 fps (long barrel) This points to an airseal problem around the hop, but all parts are the same apart from barrel lengths My question is this How can I upgrade to around the 340 fps on the stubby with such a small barrel. Do I have to increase spring and bore upthe cylinder Any answers greatful Paul Or
Hibernator Posted January 15, 2012 Posted January 15, 2012 Assuming the two hop units are also identical, so it can't be different dimensions effecting things I'd say it's the hop rubber in your new barrel. You might not have installed it 100% correctly - it could have gotten moved/pinched when you reassembled the hop. Take the hop unit apart and reinstall, try a different hop rubber if possible.
Supporters TPI Posted January 15, 2012 Supporters Posted January 15, 2012 I think it`s only going up because of the length of the inner barrel so yes a spring upgrade is necessary as i think a barrel will only add 2 or maybe 10 FPS per inch depending on how tight it is and try cleaning and lubing it all up and also the gearbox will need Greasing NOT Lubing
c2ash Posted January 15, 2012 Posted January 15, 2012 I think it`s only going up because of the length of the inner barrel so yes a spring upgrade is necessary as i think a barrel will only add 2 or maybe 10 FPS per inch depending on how tight it is and try cleaning and lubing it all up and also the gearbox will need Greasing NOT Lubing its my agm stubby hes on about lol it has a 6.03 barrel in it and a m110 spring fitted i will check the hop rubber and make sure its in right but it is a new one
REMSoft Posted January 15, 2012 Posted January 15, 2012 The cylinder will need changing if you are using aren't using the stock one designed for that barrel length. Different porting sizes effect FPS with specific barrels.
c2ash Posted January 15, 2012 Posted January 15, 2012 The cylinder will need changing if you are using aren't using the stock one designed for that barrel length. Different porting sizes effect FPS with specific barrels. been done plus cylinder head
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