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Custom Hopup's

4438 Views 38 Replies 6 Participants Last post by  bobgengeskahn
Well figured I would beat BOB to the punch......

Lets hear all of our LRB design options, or anything else that you may have.....
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Dam! You gota love ingenuity and creative thinking for the greater good!!
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I think this 'spinning on 2 axis' idea is all nice n all, but I'm not sure Its feasible with-in the confines of an airsoft rifle hop system, I can see it working as an alternative to the gearbox though if anyone wants to take it down that route.

I can also see a problem with regulating/tuning fps due to the fact there is not really a need for a pneumatic system to propel the bb as its all done via 2 spinning wheels, making it to easy for the operator to increase fps in the field with the quick twist of a screw, at-least the current 'quick change' systems that are in place require an element of taking stuff apart to do it :-/

Sorry to poo-poo anyones ideas, and if they have the machinery etc to do it then do carry-on, I'd like to see the results, I just feel we should steer clear of 'pie in the sky' ideas and stick to stuff we all can do with a dremel and some other basic tools..... such as bobs long dual hop, and the theories behind why it should/does work, now I think there, and other similar ideas, is something worth pursuing ;)
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Not sure you'd get the range, but the accuracy would be there.... if it were to work :-/

I'm also not convinced just by having, say, a nub at 45 degrees would guarentee a spiral rotation in the bb, more likely it would send the bb down the barrel in a spiral to which it would pop out the end and fly off in a random direction, all be it the same direction if the hop was made stable enough :-/

I'm gona stay on the path of long hop and LRB for further development in both my EBR and my latest project VSR to see if 1 works better than the other and then try to get the straggler to the same level of perfomance as the other, and so on.....

A note on those interested in LRBs, its worth considering the material the barrel is made from, as its in the end its where most of your friction is going come from, so a teflon coated or stainless steel barrel are going to slide much more than your average brass barrel, to this end I've stopped polishing the barrel that is due to go into the latest V3 AUG unit in the EBR (currently in another weapon system ;) ) and am just passing a spirit soaked swab down it to clean out the crap.

When time allows photos and verdicts will be posted here :)
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For those who are interested, along side bobs experimental hop system, I too am experimenting with a combination of a long hop nub with an LRB in both my EBR and soon in my latest VSR project.

I've done versions 1 and 2 in the EBR, and both showed signs that good things could come of them, despite a few hick-ups along the way, in time I'll post pics of V2 and if I can find it the parts left from V1.

V3 is about to started on and if it produces the goods I'll do a full run down on its development.
Been a busy boy this week, what with doing #1 VSR project and finding enough time to do this too....

Here are some pics of the mods I've made to my AUG hop in my EBR.

First is the new extended nub....

How it fits into the outer barrel.....

The length I opened out the barrel window to take the nub (430mm x 6.04 Systema for those who care).....

The nub profile and how I made it from laminating plastic card to the right width for the hop window, you'll also notice the rubber patch on the nub, this runs the whole length of the nub and its purpose is to take into account the very slightly differing sizes in bb as they pass under it (this is actualy 1 that I've made for an M4/16 hop unit that i'm experimenting with, and is actualy alot narrower than the 1 used in the AUG unit but you get the idea).....

A couple of the hop adjusting system, its alot more accurate and is very sensitive to fine tuning.....

This is the LRB adjusting screw, the 2 front bolts of the top cover have been tapped to about 3 times the depth of the stock screws to take the strain of the screw and return pressure of the outer barrel trying to remain straight, you can also just see the notch I cut in the faux gas tube to allow the barrel to be bent unimpeaded......

Thats about it really, except a nice little mod worth concidering if you to use an EBR, I seen this on a RS EBR site and thought it a good idea, a trigger shoe that actualy brings the trigger into a more user freindly angle, this is made from a trigger I found amongst my bits, obviously from a V3 box but god knows which gun :-/.....

And lastly a pic of the entire weapon, though she has been re-scoped now to a larger 40x4 scope......

I had chance to test fire and set up the nub and LRB this afternoon :)

I set the nub so as to just hold the bb in the barrel, I then tuned the gearbox to put out 340fps, with this set up and no LRB effect it would massively over hop a .36

Now, not being able to reduce the hop anymore or the bb would roll out the barrel, I dug out a bag of old .43 straights I had left over from when I used to play at 500fps and tryed them.

With no other mods these flew straight for about 30 metres* then dropped off, so I started applying LRB effect to the barrel, after about an hours faffing about I managed to get the .43s to fly straight and level out to about 70 metres*before it drops off ( a rough estimate done from side by side testing next to my 350fps VSR using .28s), not bad from a rifle only doing 340 (max) fps ;)

Given some more time I'm going to see if I can extend this a little further or if I'm just over estimating the systems abilities, it may just be a case of investing in some .4s instead and see how that goes :-/

The other thing that needs to be looked at is some lateral support for the barrel as I think it might be vibrating and affecting accuracy a small amount, but then it was quite windy when I was doing the testing and it could of been that :-/

We're playing again in 2 weeks in woodland, so the system will be tested more thoroughly in a combat situation, to determine how effective/practicle it really is ;)

And now onto project VSR #2, to include long nub and LRB to see what I can get from that

* All ranges are estimates taken from a 25 years experience as a builder, as I test shoot across private land so cant take accurate measurements :(
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bobgengeskahn said:
1. I am assuming you still used a shaved bucking, tied and teflon taped?
2. What method did you use to cut the barrel? For my build I am thinking about ways to do it with a drill press, but due to the nature of the cut I'll be trying to make I'm not sure how to do it cleanly.
Yup, shaved bucking, tied at the very front so as to allow the rubber to stretch easily into the longer window.

Barrel was cut to length using a fine tooth mitre saw, all other mods done using a Dremel, a steady hand and a big sack full of patience ;)
Yup, I prefer a hand powered saw as its more controlable over a spinning blade that has a proportionaly higher chance of buggering things up if you slip ;)

All I do to finish it up is run a countersink into the bore by spinning it between my fingers, use a flat needle file to round off the outside edge and then I get a piece of scotchbrite pad and then spin the end of the barrel on it between the flats of my hands, abit like I'm trying to start a fire using a fire drill, just change the position on the pad regularly and keep doing it until its nice and shiney
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bobgengeskahn said:
Ooooooh... I think I missed something initially... I was wondering about the extended barrel cut... although those pipe cutters work great for shortening the barrel... and making o-ring groves ;)
Ah, sorry wrong end ::)

I use my dremel and 1 of these......

Then finish off the opening with a selection of flat, half round and round needle files making sure all burrs and sharp edges are removed inside and out ;)

A quick note on using pipe cutters to cut your barrel..... while their a nice idea, and technicaly what their designed for, they are no good for barrel cutting as they rely on brusing a blade through the metal, what this does is gently crush the end of the barrel giving it a far worse burr over to clean up than if you were to just use your dads blunt and toothless hack saw out of the shed ;)

In some types it will even choke the end of the barrel to the point that only alot of grinder work will enable a bb the ever get out the end

Then, after you've sawn it through, just follow what I do to finish mine off in the post above and your barrels will be perfect every time
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