DE UTR45 - very erratic hop?

[The_Lord_Poncho]

Hi all - upon trying out a new DE UTR45, the hop seems to be incredibly erratic - varying from being spot on (and stunningly accurate) for ten shots or so, to dramatically underhopping (i.e. no hop being applied by the unit at all) for a random number of shots, to then overhopping etc etc. No real logic to it!

Only thing i can think of before I strip it down to take a look is that there is some excess grease inside the new gear box/cylinder that is finding its way onto the hop rubber?

I am assuming that a standard AR style Hop unit (e.g. ZCI Plastic Rotary) would fit in the UTR 45 if i can't suss it out?

 

[Speedbird_666]

Have you replaced the hop rubber itself?

Hop unit was replaced in this thread here:

 

[The_Lord_Poncho]

Ah, awesome, good to know that a ZCI hop unit will work. I might just order one+ the ubiquitous macaron and Omega nub then and be done with it. Which is a shame, as all the reviews I've seen have never mentioned utterly erratic hop on these!

It has also come in on only 305fps on a .20 - nothing that an easy spring change can't solve though.

 

[RostokMcSpoons]

Have you looked inside the hop unit and the rubber yet? 
While some grease getting onto the contact patch is always a prime candidate for losing the ability to hop, the fact it's so variable suggests something has got knackered / stuck / loose and the nub is moving around while you shoot, or perhaps the bucking has a split in it?

Get the barrel + hop still attached out of the gun and make sure that moving the dial changes the inner profile of the bucking as you'd expect, and that there aren't any (technical term ahoy) 'flappy bits' hanging off the lips and getting involved.

 

[The_Lord_Poncho]

Sage advice  - I shall do as you suggest. Having had a ganders at Pheas Airsoft's strip down video, it looks pretty straightforward to get to the barrel/hop group at least. I think you are probably right - grease on the bucking wouldn't dramatically clear after ten or so shots to head back into overhopping territory.

 

[The_Lord_Poncho]

In way of an update - I popped a ZCI hop unit in + macaron bucking. It really didn't like the macaron - wasn't reliably feeding, so I used the bucking that came with the ZCI unit. A few times to reassemble due to the hop unit not being entirely centred on the barrel, but all good now. Still not really sure what was up with the original hop unit/bucking - it didn't look damaged.