Madbull Ultimate Hopup fitment problem

[Jackarutu]

Has anyone besides myself ran into problems getting the Madbull Tight Bore Barrels to fit into the New Madbull Ultimate Hopup?

The promotional video makes it look very easy. However, I found in reality that the Madbull tight bore barrel because of it's coating is a very tight fit into the hopup unit and it cases the hopup rubber to stretch and pull back into the slot where the inner barrel clip goes.

The only solution I found was to use a single edge razor blade and trim off about 1/16 to 1/8 inch of the hopup rubber. Then when it stretches it doesn't pull back in the the clip slot.

When I used a regular plain jane oem inner barrel no problems they slide right into the hopup with no problems. It's just the Madbull tight bore barrels that seems to have this fitting problem.

I thought perhaps I had a bad one so I opened up 15 of them and all had the same problem so either I have a bad batch or . . .

Any comments?

[DarkAngel]

If your using Anything other than Madbull Hop up Rubbers with the Madbull teflon barrels, you will have the above fitment issue. The reason being that Madbull teflon inner barrels have a slightly smaller outter diameter than standard IBs. Best way is to use MB Rubbers with the Teflons and wet your finger with some water and coat the outside of the hop up rubber as you slide it in with a twisting motion. Pretend the Hop up is your Girlfriend, and the IB + Rubber is a dildo

IMO Razors, knives etc have no business being near hop up rubbers.

[Styrak]

Use lube. But only on the outside of the hop rubber.

[Jackarutu]

No matter how clearly one thinks they are communicating there is always room to be misunderstood. Of course I was using the Madbull Hopup rubber. How could I do otherwise: they come with the hopup.

For those not familiar with these hopup rubbers they are very special because they have a bump molded into the rubber where it aligns with the bucking slot.

And yes I wet the outside of the rubber with water before trying to insert the inner barrel with the hopup rubber attached and I'm still claiming the fitment is way too tight on the ones I received. Possiblely the problem is the inside diameter is too small inside the hopup because I use Madbull tight bore barrels with other hopups all the time and no fitment problems ever in those cases.

“The reason being that Madbull teflon inner barrels have a slightly smaller outer diameter than standard IBs.” Fact is I find them to be larger in diameter than any other inner barrel and as I see it this is the problem because as I said in my first post any standard OEM barrel I have tired slides in perfectly no problems.

Edit: I went back and notice those OEM barrels I claimed no problems with were all JG OEM and they are indeed smaller in diameter. When comparing against a actual TM OEM inner barrel they are in fact same size as the Madbull and have the same fitment problem.

I realize I might be having a senior moment and just over-looking something that might be totally obvious to one of my peers.

Edit: I tired the twisting action suggested and my results were the fit is so tight that it causes the rubber to stay positioned and the inner barrel to twist out of the alignment with the rib on the inside of the hopup rubber so even if it would slide all the way in the inner barrel would be out of alignment with the bucking slot. Still it stretches the rubber leaving just enough of it sticking out into the clip slot that one can’t get the clip to slide home correctly.

What possible harm could come from trimming off some of the hopup length?

[Green]

Have you tried a different hop up rubber?....I'm assuming that you are using the madbull 60 degree blue rubber that comes with the hop up unit. I've tried a couple of those rubbers (granted on a different IB and different hop up unit) but I experienced the identical problem you described.

Either try another rubber or you could lube that rubber with a water-based lubricant (KY--no joke). Dont use anything else like silicon lube because it will engorge your rubber and actually make it larger.

[Jackarutu]

Greenpunk, you may be 100% correct because after lubing it with water didn’t work my second step was to use silicone lube and if you’re correct all that accomplished was to exacerbate the problem.

I haven't tired other rubbers yet because I wanted to give it a good try out as packaged from Madbull to see if that blue rubber actually offers any improvement. I’m not aware of any other rubber that has that extra thickness (bump) where the bucking nub makes contact with the rubber.

Until now on my custom builds I have been using the Echo1 one piece metal hopup with the Element 45 Hard hopup rubber and they slide into place very easy when using a MB IB.

When comparing the rubber that comes with the MB hopup to the Madbull Item # R860 60 degree rubber they don’t have the extra bump even thought they are blue. They are not the same rubber that comes with the Madbull Ultimate hopup.

[DarkAngel]

I was half dead when i posted as it was 3am, i ment inner barrels are smaller in diameter.

As for hop up used. I had no idea what hop up rubber used as you did not clarify that in your origional post. Many of us toss the Madbull Rubbers and opt for the much superior Guarder Clears (Unless your using a Madbull TB). If your unable to twist the barrel + hop up, it means theres still too much friction and not enough lubricant. Ive installed 4 of these units for clients already without any issues.

And the reason you dont slice or cut up your rubber is simple, it can compromise the shape and strength of the rubber causing it to go out of alignment with the Inner Barrel.

Also Most Aftermarket Hop up rubbers have the premoulded bump built into the rubbers. Madbull is just one of the few available. Its pretty much assumed that people will use an aftermarket rubber when they purchase a TB and a Hop up unit.

And Greenpunk is correct, do NOT use silicone oil with hop up rubbers. Itll engorge it, same with Orings.

[-Ace-]

I have this problem too...the above fixes have not solved the problem. I tried the Madbull rubber that came with the hopup unit and it's apparently too big for the chamber, and because of this, the C clip wouldn't fit in and i can't use the hopup.

[Jackarutu]

"And the reason you dont slice or cut up your rubber is simple, it can compromise the shape and strength of the rubber causing it to go out of alignment with the Inner Barrel."


I just don't get this. I was speaking of trimming off just a 1/16 inch from the end opposite of the bucking by pressing both sides together and using a razor to make a very fine slice so that when the rubber stretches as you slide the inner barrel home it doesn't pull back into the clip slot. I can't see how this could interfere with the action of the bucking. I think we are two people divided by a common language

[DarkAngel]

Think about it this way. a cylinder gets its strength from the even distribution of force applied to the whole surface, If you cut a small portion of it to disturb that even distribution, it completely loses its ability to distribute that force, causing the shape to collapse. The same is true for Hop up Rubbers.

While depending on where and how you cut it may compromise it to different degrees, it still will affect it in some way. IE, not enough surface friction, causing the nozzle end to stretch over and pull over the IB, Pieces getting caught during installation due to unstretched pieces snagging etc.

[CJay]

bud this is a very common problem with the black python line barrels - worked on literally buckets of the things and the only thing I've found that fits it is the standard King Arms Hop chamber that u get with the king arms metal body kits. I even had this problem on a few P90's I've worked on and that hop unit is entirely different so don't feel bad - only way to get it to work is to persevere - i personally apply a small amount of teflon grease to the outside of the rubber and u can usualy work it on - slow going but only way so far :S

[coach]

just finished installing the madbull ultimate hopup unit with a guarder clear, scs and madbull TB. this combination has solved my air leak issue. no problems with install.

no fitment issues other than I have some problems seating a couple mags fully, and when they are fully inserted into the mag well, they are very tight and don't come out easily. need to either dremel a part of the metal body or just deal with it. it may also be my mag release on a slight angle as well. JG box in a CA body has a slight fitment problem but it's a small compromise for the time being.

no feeding issues to note. tested with CA metal midcaps, TM metal lowcaps, TM metal highcaps, KA plastic midcaps and S.Arms midcaps (the only ones that are hard to insert and get stuck on removal)

[Schwag]

gotta disagree with darkangel about cutting rubbers.
The hop up sleeve's length is nearly irrelevant as long as it's not cut too close to the nub that descends(like so close it will pull into the barrel) The only thing that is affected is the extra padding and tension it provides between the IB and hop up unit.
Obviously if it fills the whole tube it will provide better stability but even that isn't much of a difference if the barrel and cut sleeve are tight.
There have been times when I have had to cut sleeves to fit guns and times where it was so tight that using a shortened sleeve was the only way to push it all the way in without warping the outer ring.
This may not apply to all applications but I've cut many a rubber with zero issues.

and maybe I'm thinking about a different barrel but all the madbull tightbores I've seen have thinner walls and a smaller diameter with thicker hop-up sleeves to compensate.

how are you guys liking the ultimate hop-up?

[coach]

Originally Posted by Schwag

how are you guys liking the ultimate hop-up?

loving it. can't wait to get it out to tune the hopup and see how BB's fly.

[Kos-Mos]

If you only have 1/16 left, then you should not have to cut it.

Just place the barrel in there. When you reach the end, pull back on it for about 1/8" and then push back again.

Repeat until the rubber position itself properly.

Yes, it works, just takes time.

Other than that, I have just (as in 2 hours ago) installed a Madbull V2 tightbore into a TM AUG. Fitment was nice, but the outer diameter is definitely smaller. The guarder clear rubber I installed was sloppy a bit until I insert it into the chamber.