[Mazw]

Hi

Has anyone ever experimented with FPS decrease as hop up is applied?
If so how much decrease in FPS is "normal" as you apply hop up?

I am only asking as I skirmished with a new gun (well two actually) today and could not get the hop ups to set up properly. Both however were using the original chinese hop ups supplied with the guns.
Both on the chronograph are capable of a large (40 + FPS) reduction in FPS as the hop up is applied.
Does this mean new hop rubbers are needed in both guns ?

I hope the above makes sense to someone with some technical knowhow.

Mark

[Andy Hawkes]

Hi

Has anyone ever experimented with FPS decrease as hop up is applied?
If so how much decrease in FPS is "normal" as you apply hop up?

I am only asking as I skirmished with a new gun (well two actually) today and could not get the hop ups to set up properly. Both however were using the original chinese hop ups supplied with the guns.
Both on the chronograph are capable of a large (40 + FPS) reduction in FPS as the hop up is applied.
Does this mean new hop rubbers are needed in both guns ?

I hope the above makes sense to someone with some technical knowhow.

Mark

You'll always get a drop in FPS with the hop set vs. fully off - there's a bit of rubber putting back-spin on the BB and therefore slowing it down courtesy of the ensuing friction.

The trade-off is that you get better range due to the effect of Bernoulli’s principle.

A new hop will take time to bed in as you're going from a "fresh from the packet" smooth rubber to something that has gradually had its surface slightly abraded and will therefore offer greater resistance - it will take time and adjustment to "bed it in" and get the best settings for your gun (and for how you want to shoot it - some people prefer a gun with more hop-up, some prefer marginally more punch in exchange for less accurate range).

[The Keeper of Secrets]

As said above, the friction from the hop rubber will slow the bb down. However the point you raise is a good one. Usually assuming a healthy gearbox/spring mechanism and good hopup, only about 20-30max fps should be removed with the hop set. A very good indication of a bad hopup unit is a decrease in FPS or even a jam when the hop is applied. If you get a drop of anything above 40fps then you should be raising an eyebrow. G&P M4 units can rob the gun of up to 100 fps and are a good example of a unit that should be changed out upon recieving the gun.

Your case.

You say a 40fps drop is being registered on the chronos, this seems like something to worry about. Do the hops actually apply hop or just slow down the fps? If you get to the point where, in order to get the accepted hopup trajectory "shape" (curving up very slightly before coming down), your range and fps are greatly decreased, then it's probably time to start looking at replacement hops. Here I cannot recommend TM enough, cheap and more than enough. If you fancy splashing out, as cliche as it is systema make very good rubbers, madbull are nice too. any standard AEG rubber should fit assuming it's an AEG hop and not a specific spring/gas one.

If the problem persists, it may be the hopup chamber itself that is in bad way. It has been known to happen and again G&P units are a prime example. New hopup chambers are not as easy to find as rubbers for the obvious reason of you needing to get the exact one for your gun. Hence why I'd recommend trying the rubber change first.

I hope this helps, let me know how it goes

[Mazw]

As said above, the friction from the hop rubber will slow the bb down. However the point you raise is a good one. Usually assuming a healthy gearbox/spring mechanism and good hopup, only about 20-30max fps should be removed with the hop set. A very good indication of a bad hopup unit is a decrease in FPS or even a jam when the hop is applied. If you get a drop of anything above 40fps then you should be raising an eyebrow. G&P M4 units can rob the gun of up to 100 fps and are a good example of a unit that should be changed out upon recieving the gun.

Your case.

You say a 40fps drop is being registered on the chronos, this seems like something to worry about. Do the hops actually apply hop or just slow down the fps? If you get to the point where, in order to get the accepted hopup trajectory "shape" (curving up very slightly before coming down), your range and fps are greatly decreased, then it's probably time to start looking at replacement hops. Here I cannot recommend TM enough, cheap and more than enough. If you fancy splashing out, as cliche as it is systema make very good rubbers, madbull are nice too. any standard AEG rubber should fit assuming it's an AEG hop and not a specific spring/gas one.

If the problem persists, it may be the hopup chamber itself that is in bad way. It has been known to happen and again G&P units are a prime example. New hopup chambers are not as easy to find as rubbers for the obvious reason of you needing to get the exact one for your gun. Hence why I'd recommend trying the rubber change first.

I hope this helps, let me know how it goes

Yes thats what I was trying to get at.

The reduction in the FPS seems to be having more effect on the BB ie reduced range that any gain in range from the hop up effect.

The two guns on sunday were a A&K M249 where the hop seemed to be having no effect at all. And the other was an A&K SVD Dragunov with the same symptoms.

[The Keeper of Secrets]

Ah yes, I remember talking to you about the Drag on the sunday game just before I lost my key.

That's the second A&K Drag I've seen with a bad hopup unit. I remember you saying they have an AEG sytle hop so a new hop rubber looks like it'd be a good investment.

As to the M249, I myself own one, and have completely overhaled the internals with TM/CA/Systema parts. The first and formost thing I did was to fit a TM rubber and customise my own hopup bucking. The range is now fantastic and the hop robs all of 5fps from the gun.