Hop-up affects FPS

GrumPy

Would I be right to assume a chronograph would read a bullet to be traveling faster when hop-up is fully on? ie. creating more backspin.

Seemed to be the case in the warehouse the other night. Gun went from .58 to .80 which is a fairly big jump after the hop-up was adjusted. Wonder if this could lead to dodgy readings.

Ie. Gun firing at a steady .85-.88 of a joule, change hop-up setting much 15-20 stages higher or lower?
Wouldn't fancy getting hit in the hand by a rifle firing well over a joule just cause hop-up setting was low when tested :eek:

A gun firing .97 consistently, increase hop, increase speed to 1.20 or whatever would be messed up.

Dread-Lock

Other way around. When the hop up is off your gun will be shooting at a higher FPS.
That is why sites get you to turn off your hop-up (or at least they're supposed to) before the chrono test.

Masada

In cases where the guns fires with more power with hopup on, the cause is usually the lip on the hopup rubber isnt holding the BBs back the way it should so they are leaving the barrel too soon, hence the lower power.
then by turning up the hopup a little it holds the BB back and the increase in resistance means more of the cylinders volume of air can propel the BB so in turn, more power.

however the output can only be that of the rating on the spring and cylinder it cant be higher. there is no way to increase velocity with the hopup so if it fires over the limit, hop on or off, then the spring is too powerful. the circumstances you discribed sound like a perfectly legal gun with a dodgey hopup rubber.

GrumPy

Masada wrote: »

In cases where the guns fires with more power with hopup on, the cause is usually the lip on the hopup rubber isnt holding the BBs back the way it should so they are leaving the barrel too soon, hence the lower power.
then by turning up the hopup a little it holds the BB back and the increase in resistance means more of the cylinders volume of air can propel the BB so in turn, more power.

however the output can only be that of the rating on the spring and cylinder it cant be higher. there is no way to increase velocity with the hopup so if it fires over the limit, hop on or off, then the spring is too powerful. the circumstances you discribed sound like a perfectly legal gun with a dodgey hopup rubber.

Hmmm... Tis a brand new gun though. TM too... Maybe that hi-cap I had was a mix of two arse bottles of bb's, some .2's, some .23's.

I suppose that could be the issue?

Masada

Yeah you would have to use .2's as a base line and from a decent maker. once its less than 328fps your fine. it might also be that the hopup needs running in.