[Leo Greer]

No they are not. I’ve had feeding issues with G&G green in the past, especially in stock hop setups.

You have two choices: sand the lips, or get a new rubber.

There seem to be two hop rubber fitments—long and short. It’s why ML rubbers work with G&G units without mods, but not with Prowins or any Prowin clones.

 

[mr. potatohead]

Thanks guys. Yep the stock dytac hopup is a prowin clone. I'll try shaving them lips down and will update once that's done. Man too bad I lost the original stock packing, would've been a good template.

 

[mr. potatohead]

Well I shaved the lips down to where they're about out of view of the feed tube (tiniest sliver viewable, sanding them cautiously). Tissue test failed (got blown towards the heavens), and FA still a mess. Possible I haven't got the sanding down right yet, but I'd think there'd at least be some noticeable improvement.

 

[rm105]

possible your nozzle length is now incorrect - need to adjust both unless the nozzle was originally a bit to long. Might be the right time to introduce an adjustable nozzle as who knows what the right spec will be after shaving the lips down.

 

[Leo Greer]

Maxx adjustable FTW

 

[mr. potatohead]

I'll get the adjustable as a last resort lol. I tried to compensate for the shaved packing lips (not visible from feedtube unless viewed from and angle) by shaving down the front of my tappet plate (fin already cut past sector gear post, allowing me to do this) so that the nozzle seats farther forward.

I tried tissue tests with weak/stronger lipos and found that the gun almost passes the tissue test both in semi and FA when using a weaker battery. Consistency looks better, but the chrono tells me every other shot is like 5-10 fps lower than the previous in semi. FA is still almost 100 fps drop. Oddly enough the tissue barely vibrated off the hopup during the test and the bb spread is fairly tight.

When I used the stronger lipo, fps immediately dropped by ~30 on semi from the previous weaker battery test. FA drop was about the same as the weaker battery test, but bb spread was bad.

I then did all the tests again but swapped the sp150 (using to check for PME) back to the original sp140. I literally got the exact same scenarios for both batteries, with FA once again looking a little rougher with stronger battery even though readings looked about the same.

Here's the symptoms I've got currently:

1. FA drop by about ~100 fps from semi to FA
2. Every other semi shot is ~10 fps higher than the previous shot
3. Tissues test almost passed with weaker battery, but totally failed both semi and full with the stronger battery
4. Piston parks at different places during semi
5. Semi immediately drops by by 20-30 fps when going from weaker --> stronger battery
6. FPS drops are about the same with both weaker and stronger lipos/weaker stronger springs
7. FPS dropped from around 320 to 260 after messing with the packing.



Before you guys diagnose, here's a few other things I've done to my gun (12:1 DSG) as of now:

1. Hopup unit is shimmed with 4 o-rings and has nearly no play
2. Packing lips on G&G green were shaved down, and so was tappet plate front
3. Tappet plate is an SHS and the fin was trimmed past the sector post to check for tappet PME (release point was like 3 teeth and no feeding issues as of yet)
4. Tappet return spring is cut by ~2 coils
5. Hopup unit is stock, prowin clone
6. Piston assembly is barely 18g and spring is a guarder sp140
7. RPS is 40-45 with mostly drained batteries
8. When testing, mags were half-full (no midcap syndrome)

 

[Leo Greer]

For all the world that sounds like tappet PME + tappet jump.

What nozzle/cylinder head do you have? I’m assuming you’ve already checked for friction between the nozzle and the CH, and between the tappet and tappet rails.

You mention that the piston ends up in different spots every time. You have an ETU with active braking in there, right? Does AB help any?

Without knowing any more, and assuming you’ve done all the usual checks, here’s my tentative diagnosis; the tappet is pulling the nozzle in a certain direction and causing additional friction on the o-rings I’m assuming you have on your nozzle. O-rings heat up, even more friction.

My secondary diagnosis would be that the tappet is again pulling the nozzle, but is simply sealing incorrectly due to mis-positioning (similar to mid cap syndrome but all the time, and not as pronounced). I recently did work on my own DSG project, and had an issue that only became apparent when I started using that Aztech Apache CH: the nozzle was actually scraping on the top of the hop unit and getting stuck unable to return. While the gun was still an SSG, the problem was hidden, because the sector manually pulled the tappet back every time, but the spring on the Apache wasn’t anywhere near strong enough. In my case it was actually caused by the angle of the hop unit, since the gearbox was actually a different maker. The hop unit seemed to seat perfectly, but was actually too high.

 

[mr. potatohead]

Yeah, no apache for me as of now lol. Nozzle is a plastic stock LT (not bad, actually) I found as the actual dytac stock nozzle got deformed some how. No o-rings and extremely low friction with the Lonex cylinder head I have. I would assume the angle would be ok with the hopup since the LT I had used a prowin clone pretty much exactly like the dytac model currently being used, but I'll check for rubbing. Tappet is greased on both sides, no resistance in the rails. See, this is so weird, the symptoms are almost contradictory at this point. I'll get around to messing with my gate settings - can't remember the last time I did. Hopefully that can clear a bit of this mess up.

 

[Leo Greer]

It is genuinely weird.

I like those stock LT nozzles as well. One note; that nozzle could be pushing the BB too far past the packing. Mine was causing inconsistent FPS and feeding issues, so I had to crown the inside so it seated the BB correctly. I used a Maxx adjustable to find perfect seating, and then filed to match, and now it works perfectly. Of course, yours could be different, but at this point you’re into the range of looking at things like this.

 

[mr. potatohead]

More clues have been discovered. I lightly crowned my nozzle and sanded the front of the tappet plate further to press the nozzle into the packing (and also eliminate the possibility of a gap). I then realized that because my tappet fin was actually past the sector post (I had trimmed it to above the sector because the plate could go further but the sector post impeded the fin; sanding front of tappet pulled the tappet even further forward), my tappet return spring (trimmed a couple coils) was now the equivalent of a stock one (tension was lost to some degree). I trimmed the spring 1 more coil (might cut another off). Here's where it gets interesting:

When I did the tissue test in semi, the tissue was blown off the hop slightly. However in FA, the tissue was sucked in (never had that happen before). Suction I guess? Before I did the most recent above mods, I never encountered this, and always had the tissue blown off in FA. Piston head is a lonex pom. I found a thread where [mention]Jimps [/mention] had this same issue with the prommy head. Ultimately the prob was tappet PME due to the SHS tappet + SC 9-tooth combo, but fps did improve a bit when the ports on piston head were widened more. I seriously doubt I have tappet PME at this point, and according to jimps's testing the lonex pom didn't vacuum as much as the prommy, but opening the ports might help? Oh and I gotta get around to messing with my GATE settings, possible something's a bit off.

 

[Leo Greer]

It doesn't matter as much since most of my builds are at 25-35 RPS, but I've seen the tissue sucked downwards a little bit on several builds. I'll try to go back and test and some point to see which ones "sucked" and which didn't on what piston heads.

 

[rm105]

Your build sucks?

Full cylinder or ported? Polished cylinder? Oil or grease on the PH oring? Does ROF control or a weaker battery effect it?

Never particularly noticed this, at a glance it sounds like a timing issue but could also be something that becomes more prominent with speed, IE there's always some suction through the feed on the reverse stroke but as rps goes up so does the vacuum?

 

[Leo Greer]

random little pun there.

Honestly, i just remember the tissue dimpling downwards a tad when i did the test--Can't even remember which build I was working on. It definitely did not suck. At least not completely.

I'll try out ROF control and weaker battery when I can and update with more info.

 

[mr. potatohead]

Your build sucks?

Full cylinder or ported? Polished cylinder? Oil or grease on the PH oring? Does ROF control or a weaker battery effect it?

Never particularly noticed this, at a glance it sounds like a timing issue but could also be something that becomes more prominent with speed, IE there's always some suction through the feed on the reverse stroke but as rps goes up so does the vacuum?

Not sure if this is for me or Leo, but I'll answer for myself. Cylinder is ported, but far enough back that the piston head never reaches it. It's polished and cleaned, but there's oil now. Silicone oil on the PH oring, yes. Have yet to test a weaker battery/rof control as of yet. I would think more people would run into this (you would have probably seen this in your builds that double my rof lol), but since I haven't come across too many cases, I'm assuming I did something wonky, or my parts don't like each other. All I know is that tissue (and it wasn't that small lol) got freakin sucked all the way down that tube, almost disappeared on me lol.

 

[mr. potatohead]

I've discovered more, but I'm still scratching my head. I did the tissue test/test fire with a weaker battery and this is what I found:

1. Semi blows the tissue off arguably higher than when a stronger battery is used
2. FA totally blows the tissue off
3. Semi shots look really consistent (didn't bother chronoing)
4. FA spread is tighter, but not a laser

I redid the tissue test with my regular stronger battery to make sure last time wasn't an outlier:

1. Semi still blows the tissue off, but varies in power. Sometimes it's blown pretty far up, other times not so much, and occasionally it won't move.
2. FA definitely sucks the tissue straight in still

So TLDR gun performs better accuracy/consistency wise with a weaker battery, tissue is blown off (in semi) with both a weaker and stronger battery but varies more in results with the stronger battery. In FA tissue is blown off with weak battery, but sucked in with strong battery, very interesting.

 

[mr. potatohead]

[mention]Leo Greer [/mention] you might be on to something, as I found a smallish ridge on the top of the inside of my hopup. Possible the nozzle is catching, but I suspect there are several additional issues at play here as well.

 

[Leo Greer]

Airsoft can be plain weird sometimes. Usually at this point I just start changing out parts for whatever I have laying around until it works.