How to make a very simple adjustable hop-up system

[Kash munni]

Essentially all a hop-up system is is some sort of material (preferably rubber) that portrudes downward into your barrel. When the BB hits the rubber on its way out the barrel it gets backspin, like so:



If you know that, then you can basically come up with a variety of ways to do it yourself. This is how I did it.

I cut a notch in the top of the barrel near the breech end so it looked like this:



The I slid a piece of rubber over the notch. You could use anything that's rubbery, like a piece of balloon or an o-ring. It looked like this:



After that, it's just a matter of making it adjustable. I did this buy putting another tube (cpvc in my case) over it then drilling and tapping (threading) a hole in the CPVC for a flat tipped screw to fit. After that, line the notched end of the barrel up with the hole and secure it in somehow. After that, it is wise to insert some kind of foam or rubber in between the screw tip and te hop-up rubber. I used a piece of foam from a nerf dart. Then insert the screw and turn it clockwise to give more hop-up, and counterclockwise for less. The end product:



Questions, comments? Thanks for reading.

[starman]

Nice little tutorial. Other than causing the BB to rise in flight, are there any other benefits to hopping up?

[brogdenlaxmiddie]

It helps it go farther due to the lower effects of gravity... which is caused by the bb going up and it wont lose to gravity untill a certain point and thats a lot further than just a loosly fit bb w/o hop-up

[Hailfire753]

Wow, I had the EXACT same idea in my head, but I never posted it. Great minds.... I'll spare you. Actually, mine was slightly different, because of instead of the empty space around the barrel, that was incorporated into a silencer.

[Spuddin]

that is a really cool invention. but i was thinking wouldnt any contact with the bb inside the barrel cause it to loose velocity?

[starman]

that is a really cool invention. but i was thinking wouldnt any contact with the bb inside the barrel cause it to loose velocity?

Yeah I would agree, you'll have to trade some velocity and ultimate range to get the "fighting gravity" effect....you won't get that for free.

[Kash munni]

Thanks for the positive feedback guys!

Spuddin, the velocity loss is minimal, probably 10-15 fps. Still, the increase in range and way outweighs the potential velocity loss. But if you do it perfectly, then you could get more velocity because the BB would stay in the back of the barrel long enough for more pressure to build up behind it.

Starman, basically it just allows the back spin to cancel out the gravity for a certain amount of time, thus allowing the BB to travel farther. It also increases accuracy because it puts one definite spin on the BBs, and not the random spin that they get when coming out of a bare, hop-up-less barrel.

[jon_89]

I will have to give this a try. Could you up the size to marbles?

[Hubb]

I did the exact same thing (minus the screw) with my BBMG barrel, except, instead of using rubber, I used electric tape. This allowed the bb to stick to it and hold its place.

Could you up the size to marbles?

It could be upped enough to be used with basketballs if one wished.

As far as velocity loss, I would think it would be the opposite, as this design allows more pressure to build behind the round. Also, once the round begins to move, it would roll, which would not create friction like it would if it was sliding, as in a conventional setup.

[kuya]

A great alternative to the rubber is a heat shrink as it will grip the barrel nicely one its shrunk.

[django]

Great stuff man!!, Just seen this and will implimenting this Hop Up into my next BB Gun

[boom_o_matic_2.0]

I would be afraid that the screw would eventually wear a hole in the rubber. I wanted to use heat shrink too but I wasnt sure about it wearing out too fast.

[jackssmirkingrevenge]

I would be afraid that the screw would eventually wear a hole in the rubber. I wanted to use heat shrink too but I wasnt sure about it wearing out too fast.

There's a mechanical option that should be less susceptible to wear

[boom_o_matic_2.0]

I thought it was supposed to be on the top of the bb

[jackssmirkingrevenge]

I thought it was supposed to be on the top of the bb

True, in the case of that thread I was proposing the mechanism as a detent to allow pressure buildup and control rate of fire as opposed to hop-up.