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DSG FPS Inconsistency/Build Thread

8718 Views 176 Replies 9 Participants Last post by  Leo Greer
Hey guys, I recently have been working on a DSG build, but I've run into either one or multiple problems depending on if they're related. My fps is inconsistent on semi, fluctuating between 380-360 fps. On full auto, fps is even worse. One day it was around 360, so not bad. But the next day it was in the 250-300 fps range, so I don't know what happened there. Full auto shot pattern literally looks like a shotgun spread, though at least it is feeding.
Here's my parts list:

-18:1 stock gear set with shs DSG gear and stock tappet plate (<11mm)
⁃ shs high strength polycarbonate piston (SS + SC)
⁃ Matrix silent piston head (aluminum)
⁃ ASG 30k boost
⁃ Gate titan mosfet (dsg setting)
⁃ Maxx Model CNC aluminum hopup (pro model)
⁃ G&G hopup bucking (cold-resistant)
⁃ Matrix CNC aluminum air seal nozzle (ground off <.25 mm)
⁃ Matrix silent cylinder head (aluminum)
⁃ m150 spring
⁃ 265 mm inner barrel
⁃ ported cylinder

DIY mods done:
⁃ Shimming
⁃ Tappet return spring -4 coils
⁃ Everything greased/lubed accordingly

***tested with 11.1 v 2200mah 25-30c lipo and .20 gram bbs***

Most of these parts, including the hopup, bucking, nozzle, and tappet plate were used in my 12:1 SSG build, which worked just fine. I had this same problem with the SSG build but solved it by grinding <.25 mm off of the nozzle which made my fps more consistent; when it did change it was +-10 fps. Still using these parts, but encountered the same problem again albeit worse. I had already cut 2 coils off my tappet return spring, and then did the tissue test. Paper was blown off, so I thought that my nozzle wasn't returning fast enough. I then cut off 2 more coils. Paper moved slightly after that (but still quite noticeable on auto). So in total there are at least 4 coils cut off my tappet return spring and I'm still having the tissue kinda pushed off. At this point I'm even considering that the nozzle might be a hair too short (thanks to me grinding a bit off), causing hopup compression issues.

Note: This is my first DSG build, so by far I don't know everything. Any help is appreciated.
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Your chipped spur gear may have actually been a blessing. If your entire gearset was “upgraded” you may have torn apart more parts… ;)

I had an air block issue that caused PME one time (forcing the piston to remain back longer than normal due to a jammed BB), and thankfully I had a single Lancer bevel gear among the SHS spur and sector.

Stupid me kept FAing the gun, and the motor ground every tooth off the bevel. Nothing else had any issues.
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What’s your tappet spring like? The only thing I can possible think of is that your spring isn’t strong enough or you have tappet/nozzle drag, causing the tappet to bounce along instead of fully returning.

Either that or you’re getting a small jam with your packing lips.
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.
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.
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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.

Wood Lipstick Writing implement Material property Cosmetics
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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.
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. :p

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