Hop up location

[Ross49]

Good Evening

As I have asked questions and always received good incitful answers I pose another question.

Why is the hop up unit located at the start of the barrel?

As apposed to in the middle or at the end?

When providing your thoughts please ignore the fact that the bb is inserted at this end and focus on the position of the nub

Regards

Ross

 

[proffrink]

I'd imagine it's something to do with consistency. You're more likely to propel that BB across the bucking mound/R-hop patch in the correct place if it's seated in the exact same position each time rather than after having bounced off the sides of the barrel a bit on the way down.

Then there's the fact that fitting a hop unit at that end allows it to be more readily concealed by design.

Finally I'd say certain designs - particularly sniper rifles - depend on the mound and retention thingies to hold the BB in place without it rolling down the barrel unwontedly during cycling. This is also an issue with fully automatic stuff, but I'd imagine less so. You'd need some kind of retention design in every AEG, GBB, or HPA system just to stop the BB rolling down the barrel when you release the trigger.

 

[sp00n]

The hop rubber, as well as providing hop, is also a seal between the barrel and gearbox nozzle.

 

[PT247]

the hop in conjuction with the bucking lips hold the BB in place. If you wind the hop all the way off then the BB sometimes rolls out the barrel. So with that in mind the hop being anywhere but where the BB enters the barrel would mean the BB would potentially be in a different place in the barrel when you pulled the trigger each shot.

 

[ImTriggerHappy]

Physics

 

[Ross49]

Right time for some clarity

I have a co2 pistol with no hop up that fires at about 450 fps so can't use it at any site so my plan is to make a barrel about 400 mm in length and fit a hop up unit on the end of the pistol, incase the lot in a carbine kit adaptor fit a outer barrel from something like an m4.

Making a co2 sniper

 

[Sitting Duck]

why ???

there are mods to bring down fps on co2 pistols though the first few shots will still be a bit high on a fresh bulb

plus you "may" be able to find a green gas mag for that pistol

or

buy a refillable CO2 bulb that gets filled with propane/green gas and shoots at 330-ish

 

[Ross49]

First of all to see if I can do it.

2nd of the pistol cost £19.99 and I have no other use for it

 

[proffrink]

Yeh, don't bother. It's fundamentally a flawed plan for the many reasons people have listed, heh.

 

[Samurai]

On airsoftsniperforum.com a guy called vanevery built a hopup system that was at the end of the barrel. He claimed it was awesome but I always belived only the half of what he was saying.

I can't find his post though, the search there is not very good.

 

[BrightCandle]

I think one at the end of the barrel could work, but there is a fair amount of evidence to suggest that the hop starts the BB spinning and the barrel adds more backspin as it travels down and the BB travels along the top of the barrel. If you made a sufficiently long patch at the end of the barrel then presumably it could apply enough backspin. I wonder whether that would be more stable considering the transition from hop patch to material could bump the BB around it might not produce stable results.

I think its an experience that can actually be done. You need a few bits to do it. You need a flat hop bucking and you put the inner barrel in the wrong way around such the hop window is on the end not the beginning and the gun hop is actually using a flat hop and no nub so all its doing is holding the BBs and the barrel in place. Then on the end of the inner barrel you have a hop unit that is the wrong way around with a hop rubber with the lips removed and you have yourself an end of barrel hop unit. You most likely need a longer inner barrel than normal so it goes past the end of the outer barrel depending on the gun. Its a doable experiment.

The mid barrel experiment is harder, one you need to dremel a very neat hole in the middle and get the hop rubber all that way and an aligned nub none of which is easy but the biggest challenge is getting access to the inner barrel while its in the gun, every gun I know of has an outer barrel that would get in the way and would need to be cut up to make this possible. But then the best experiment to see if this could be more consistent in terms of hop is actually the end of barrel one anyway since mid is much more like the start of barrel than the end in behavior since it is kind of just like having a shorter inner barrel.