Jump to content

Prometheus new-fangled hop-up


mimesis

Recommended Posts

  • Replies 62
  • Created
  • Last Reply

Mine are in USPS limbo for over a week now--all my overseas orders have been filtering in through ISC NY and they take forever compared to LA customs.

 

The next round of barrel tests should be fun, I'll need a chart to keep track of the combinations:

 

Buckings: Prometheus blue, purple, and red

Barrels: Prometheus w/preinstalled r-hop, ORGA

Nubs: Prometheus flat and bridge, Firefly soft and medium, M-nubs

Chambers: ProWin, level travel V5

 

"Drop in R-Hop" sounds impossible to me, coz the "window" of the inner barrel from different brands may come in different shapes...

 

It doesn't need to be the exact shape of a barrel window, just small enough to fit inside. It serves no purpose for the R-hop to be exactly fitted to the window except it helps keep it from falling off, and it's actually detrimental to any adjustment--tuning the hopup deforms the scrap of rubber instead of moving it up and down. A flat bump slightly smaller than a Marui barrel window, and slightly thinner than the barrel thickness, would be more effective and work in most AEGs. Of course, a really smart company would also release a bucking with a longer flat bump and barrels made for it.

 

This is true. To supplement on that:

Buckings are stretched like crazy when you do these mods....

 

It's kinda like this, if you imagine the red line is the bucking:

 

flat2.jpg

But with a reshaped barrel window the bucking is hardly stretched at all:

 

flat1.jpg

For a good flat hop, the hole should be both longer and wider than the surface of the nub.

Link to post
Share on other sites

I just tried to install the "bridge" nub + Straight bucking on my VFC hopup chamber.

 

I tried both the stock *new* P90 style M4 chamber from VFC, and on a similar axial radial dial Pro-Win chamber.

 

I used the stock VFC brass barrel.

 

On both chambers, there was a failure to feed. I have not experienced this with either chamber before. Checked the cause, and it's that the aft lips of the bucking are too thick and get squeeze a little (not the point where it is visually deformed), just enough to stop BBs from passing through. Really had to jam the unjamming rod down hard to unjam it.

 

I then tried a Systema, followed by a stock VFC bucking, and indeed, there were no jamming issues.

 

The nub itself was almost identical to the Firefly nub in terms of dimensions, but a little wider, just a little.

 

According to my caliper, unit is:

 

3.85mm wide

6.35mm long

 

Nub packet includes both a blue (soft) and black (hard) nub.

 

Manual notes that some AEGs will require modification of the nub by cutting off the "wings". I doesn't take much to realize that doing so will dramatically decrease the "runway" length for the BB and make the unit not much different from a stock nub.

 

Fortunately, M4 chambers require no modification.

Link to post
Share on other sites

I'll have to remember to get an exact measurement on the thickness of the lips on the bucking. But they are definitely too thick for some chambers and lead to BBs consistently jamming. I still recommend Systema buckings (shaven down of course) for flat hops for M120 or less.

 

Unfortunately HK apartments don't come with indoor ranges...

Will have a fields report in a week or two. Outdoor season is only getting started here.

Link to post
Share on other sites

We're still a long way from drop-in high performance.

 

IMG_20121011_135209.jpg

 

The ProWin chambers need quite a bit of material removed to fit the Prometheus or Firefly nubs. And the barrels--even the ORGA, which has the biggest window I've ever seen, needed to be lengthened to accept it. Otherwise it's forced to tilt when you put enough pressure on it to achieve any hop, defeating the purpose. No matter what you are installing these in, I feel you will either need to cut the nubs or break out the Dremel tool.

 

The Prometheus nubs are quite firm compared to the original Firefly--the "soft" blue one is comparable to FF "hard" red, and the black one has very little give at all.

 

Prometheus or Firefly nubs are much longer than standard R-hops, so I'll have to cut one down before trying it with my pre-R-hopped EG barrel. The blue Prometheus flat bucking would seem well suited to R-hop application, but any barrel I tried in combination with this bucking and ProWin chambers resulted in the feed lips becoming far too tight.

 

Hopefully I'll have more results after the weekend.

Link to post
Share on other sites

First off, naming it "level travel" is a stretch since the platform tilts quite a bit when it's under pressure from the back. I guess you need the grub screw kit if you really want it to stay level:

 

IMG_20121011_160446.jpg

 

Also, the inside of the nozzle end is distinctly D-shaped rather than round, enough to deform the feed lips of the bucking.

 

The arm won't fit in place without some sanding, so I haven't played with it much yet. I have a Z-kit, but I'm going to try using this to make a very long flat hop instead. The platform is about half an inch long, which seems to be the main benefit to this thing.

Link to post
Share on other sites

Agreed with what kojak said.

 

I got my kit today and I was unable to shoot 1 bb because of the lips being to thick and hard! As for the nubs I had to trim it down to make it fit properly. The other issue I found was my hop unit was too tight so I had to dremel the inside to make it fit better and to stop the rubber stretching when out in. But I am still unable to shoot anything, I can't even push a BB through the unit its that bloody tight!

 

What should I do? Trim the wall of the feed lips with a small file? Or make my own flat rubber ?

 

 

http://imgur.com/3PJjm,01ncy,E9c1Q,ysfNT,d2e1c,DXaS5

Link to post
Share on other sites

Mine arrived today and put it in my Marui SCAR-L. Just trying to pass a BB through the chamber with hand seemed hard and that was at zero hop. I used a 600 grit sandpaper on the nub just a very little. The BB now pass much easier but now the hop seems slightly slanted. Will try to do some shooting tomorrow.

Link to post
Share on other sites

I've had this problem many times in the past with certain bucking/chamber/barrel combinations. Sometimes you can use a conical bit and Dremel out the inside of the feed lips, but the best solution is to find another bucking. It's not too difficult to remove the ridge and bump--I just turn it inside out and use a fresh razor blade.

 

It's a shame that the very first commercial "flat" bucking doesn't work very well, especially when the Prometheus purple is such a great product. I'm sure that there will be other offerings eventually since it's easier to manufacture than a normal bucking.

Link to post
Share on other sites

Well I managed to put it in my G&G F2000. I had to cut a little off from the end of the bucking because it was too long and the hop-up barrel lock wouldn't fit otherwise. This resulted in FPS loss but I quickly fixed it with tefloning around the bucking. Can't really tell you exact numbers on my shooting, but with 410 FPS I could hit a man sized target from 60m(longest range I could find near) easily with 0.3g and 0.4g BBs.

Link to post
Share on other sites

I'm having the same issues as every one else with the bucking. Feed lips are too thick and bbs don't feed. The bridge nub is longer than any of the windows on my barrels (Prometheus, madbull, G&P, VFC), but they're the perfect length for the hop up window on my m4 G&P hop unit, but slightly too large for the Prowin window. So instead of cutting the bridge nub, I lengthened my madbull window to fit the nub. I'm hoping to play this Saturday with both the Prometheus bridge nub setup (madbull barrel, generic flat bucking, prometheus bridge nub) and an Rhop setup (prometheus barrel, rhop, m-nub).

Link to post
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use and the use of session cookies.