Army Armament R85 Hop Up Replacement

[B.S]

I've been working on my Army Armament R85, which is kinda the reason I got it, learn by doing and all that. And if there's any gun that needs a lot of 'doing', it's the Army Armament R85. 

Thus far I've added a few screws that were missing on my gun, and replaced a few so it's all a bit more sturdy. I've fixed the screw on the safety switch so the trigger no longer moves on safe, I'm also planning to tap some more grub screws into the front sight post, and shore up the front grip. I'm not planning to mess with the internals too much just yet, I don't know much of anything about gearboxes or the piston assembily beyond the basic principles. And besides I can't afford to replace them, hence why I've got an Army Armament R85 instead of a G&G L85, or ICS in the first place. However, I do need to replace the hop up, as the one that came with the gun was missing all the adjustment cogs bar one, and it's generally pretty crap quality. The issue I have is finding a hop that will actually fit in the gun, the hop unit is supposed to be interchangeable with a standard M4 style hop up, however, the two metal hop units I've bought don't quite fit. The first one the feed hole was actually in the wrong place, and although this second one does seem to be the right shape, the gun doesn't fit back together properly with it. It's close, but just enough that you can't get the rear pin in, and the magazine gets slightly stuck in the gun.

I think because the lower reciever isn't aligned correctly. I suspect, although I may be wrong, that this is all because I've opted for a metal hop. Most plastic hops are likely slightly more malleable, and thus fit fine into the gun. I'm making this post just to see if anyone has had a similar experience or might be able to suggest a solution. My current thinking is to sand the piston hole on the hop so that it fits, however I'm uncertain if this will render it unusuable, and if I do so I obviously can't send the hop back. I already attempted a similar process on the last metal hop, before I realised it was an incorrect shape, so I'd rather save as much as possible if this hop simply won't work.

[olie93]

Hello,

 

A standard M4 Hop Up should fit fine. I us the metal SHS M4 hop on mine. I've attached some photos of mine that may help you.

 

Regards

Oliver

[RonLancs]

How are you guys getting on with these? And what is mag comparability like? 
 

Ron

[olie93]

I like mine. Most internal parts are generic M4 so easy to upgrade/replace. 

 

Nearly every M4 mag I've used works including ics, g&g and asg. 

[RonLancs]

Nice, they’re getting harder and harder to find!