VFC VR16 Feeding Issue Diagnostics

[ao_tenshi]

Wussup guys!

I've been having serious feeding issues after doing some upgrades to my VFC M4. Hoping to learn from the experienced folks here on how to systematically diagnose and locate what is the cause of the feeding problem.

Symptom:
- BBs does not appear to feed into the chamber
- I get 1 or 2 actual BB’s shot out with 5 or more trigger pulls on semi
- On auto, it shoots like 1 to 2 real shots with about 10-20 cycles

Current Setup:
VFC VR16 M4 base gun
- Lonex hop up chamber
- Lonex cylinder
- Lonex nozzle
- Modify flat hop bucking
- Modify 16:1 modular gear set
- SHS v2 tappet plate
- M100 spring

I’ve tried different hi/mid caps and got same issue, so can rule out any magazine issue. My suspicions are below but I have not been able to verify them:
1) The nozzle and hop up are not to spec to allow the BB to enter the chamber?
2) The modular gear set is not allowing the tappet plate to move back far enough? （i.e. use sector gear delayer chip? but is that only for feeding issue with auto?)

I could be totally wrong but these are all I can think of for now, and will need the experience from the community from here.

[RainyEyes]

Originally Posted by ao_tenshi

Wussup guys!

I've been having serious feeding issues after doing some upgrades to my VFC M4. Hoping to learn from the experienced folks here on how to systematically diagnose and locate what is the cause of the feeding problem.

Symptom:
- BBs does not appear to feed into the chamber
- I get 1 or 2 actual BB’s shot out with 5 or more trigger pulls on semi
- On auto, it shoots like 1 to 2 real shots with about 10-20 cycles

Current Setup:
VFC VR16 M4 base gun
- Lonex hop up chamber
- Lonex cylinder
- Lonex nozzle
- Modify flat hop bucking
- Modify 16:1 modular gear set
- SHS v2 tappet plate
- M100 spring

I’ve tried different hi/mid caps and got same issue, so can rule out any magazine issue. My suspicions are below but I have not been able to verify them:
1) The nozzle and hop up are not to spec to allow the BB to enter the chamber?
2) The modular gear set is not allowing the tappet plate to move back far enough?

I could be totally wrong but these are all I can think of for now, and will need the experience from the community from here.

Eliminate feeding issues of the mag completely by simply turning the gun upside down.

You might need to adjust nozzle alignment. There's a guide around here somewhere.

Adjust hop up so that there's some hop but not all hop.

Check for compression.

More if I can think of any.

[-Shade]

I just had the same problem with a recent M4 lonex nozzle I ordered - in a gun with all lonex parts no less. Maybe it's a bad batch, but it could be the other internals (tappet plate, sector gear clip, etc).

The nozzle wasn't pulling back far enough to let a BB through, but did fire a bit like yours. My solution was to take a fine file and very carefully sand off a tiny bit off the end of the nozzle. I had zero FPS loss afterwards doing this and the gun fires a consistent 405fps +/-1 and has no feeding issues anymore.

This is obviously a last resort kind of thing once you've eliminated other causes. You may also want to file down the front of the tappet plate a bit so it pushes the nozzle a bit further into the hopup when it fires the BB (doesn't affect how far the nozzle if pulled back). I usually do this to all my guns anyway

[ao_tenshi]

thanks the for suggestions guys. will try out the couple of suggestions and report back if the issue has been resolved or not.

[pestobanana]

May be SHS quality control. SHS tappet plates from more recent batches are off spec. Fin is too far forward, roughly half a mm needs to be removed. It causes the tappet plate to be pulled back past the its limit and the front buckles forward against the cylinder head so it doesn't snap. This pushes the nozzle forward slightly while it is supposed to be feeding a BB.

[AnthonyG]

Just going to throw this out there, try getting rid of that bucking, go back to the stock one. I had a modify one and it caused nothing but trouble in the gun I installed it in.

Sent from my Nexus 5 using Tapatalk

[shelcoof]

With me it was the Nozzle. For some god damn reason VFC is so picky with what nozzles work. I tried many different nozzles that was longer shorter and even almost the same length as the stock nozzle... nope did not work

I put back the stock VFC nozzle and the gun was shooting fine again

[jordan.santos1515]

its the nozzle and you need a VFC tappet plate I had the same problem rebuilding mine I was using a SHS tappet plate they are the same length but where the spring attaches the location is off by very little but makes a big impact when it comes to feeding. Even if you get it to feed with your current set up you won't get the proper compression either. Trust me!!! Call Canada wide airsoft he's the only guy that I know stocks them. Good luck.

[ao_tenshi]

awesome, thanks for the suggestions! I have started trying a couple already. If there are any more ideas, keep them coming.

[ao_tenshi]

hey guys, based on the comments received, I've tested the issue over and over and can now verify that its the nozzle causing the feeding issue:

with a bright light looking down the hopup chamber entry, i noticed the head of the nozzle is about 1mm protruding into the path of the entering BBs.

Im suspecting that the issue is with the SHS Tappet Plate, since the both the original VFC nozzle and Lonex nozzle are not feeding well.

[jordan.santos1515]

Told ya its just the slightest bit off its kind of weird but try the stock nozzle and tappet plate should solve your problem! Sometimes things are better left alone, Good luck with the build!!

[ao_tenshi]

Going to try to order a VFC original tappet plate (as mine broke, hence the SHS). Looks like its going to take some time.

Just wondering, would installing a Sector Gear Delayer chip help with this issue?

[RainyEyes]

Originally Posted by ao_tenshi

Going to try to order a VFC original tappet plate (as mine broke, hence the SHS). Looks like its going to take some time.

Just wondering, would installing a Sector Gear Delayer chip help with this issue?

I don't believe so? The way the sector delay chip pulls the tappet plate shouldn't pull it back further but I could be wrong. Try it out anyway, just means opening it up again and it won't hurt.

[ThunderCactus]

Sector delayers will hold the tappet plate open longer, but not pull it back any further.

If the hop rubber was causing issues, it's usually because the rubber is installed incorrectly or incompatible with the chamber. Symptom would be a BB JAM due to the BB not able to be pushed through the hop rubbers seal lip.
So if the symptom is that a BB isn't feeding into the chamber at all, it's likely an air nozzle/tappet issue if you're ruled out the mags.

[pestobanana]

Location of spring hook on tappet plate has absolutely nothing to do with it. Adding a sector delayer pulls the tappet back longer, will not pull it back further.

You know, you could just modify the SHS tappet plate like I've suggested. I've only installed about 50 of them in VFCs, so you know, maybe what I suggested has some merit.