VFC 416D Cannot Pivot Open

[THE CRAB]

Hi guys,

Recently my VFC 416D has acquired an issue where the upper won't pivot on the pivot pin. You take the rear takedown pin out and it locks up on the bolt and won't open until you take out the pivot pin itself. It's like the bolt is too far back and is hitting the lower where the buffer tube threads in.

Removing the buffer and spring makes no difference.

Gun has been fully disassembled, cleaned and regreased/lubed. Everything nice and tightened up. Gun cycles fine.

There seems to be a small gap (1 or 2 mil) where the bolt isn't fully forward. You can push on the bolt but it bounces back.

Anything obvious I should check before I send it off to the tech? The onset of this issue could be nothing but I've been burned in the past ignoring warnings with GBBRs.

Anyways, thanks for reading.

 

[SBoardley]

Pics of gap?

have you checked the ‘bolt’ face? Does it go into battery? Any debris in the hop  or around the hop chamber? Have you tried screwing the buffer tube/ receiver extension in one or two more turns?

 

[Nick G]

Sounds like the bolt isn't going fully home. As above, debris preventing the nozzle locating correctly ? I've even seen debris behind the loading nozzle inside the bolt .

 

[SBoardley]

Also. When you put it back together, did you put the buffer spacer in before the spring? Spacers and screwing in the buffer tube/ receiver extension, will increase tension on your buffer spring, which in turn insures the bolt returns fully to battery. 

 

[THE CRAB]

Hi guys, great suggestions.

Bolt face, mock lugs, barrel extension and hop were all cleared but weren't dirty anyway. I disassembled the entire front end for cleaning in the process of chasing this down.

The nozzle is in the correct position but the metal bcg thingy keeps pushing itself away from flush just slightly. Looking at youtube vids this gap should be maybe 1mm but mine is 2.

The position of the buffer tube is dictated by the detent I think so I can't turn it further without it sitting ontop of the pointy bit.

I disassembled the bcg completely so there's no dirt anywhere in there.

As far as I can tell The VFC 416 doesn't include a buffer spacer based on the exploded diagram on their site. I have been considering a stiffer buffer spring though. Would that keep the bcg further forward when you're trying to break it apart to pivot?

 

[Nick G]

If the nozzle is sitting correctly but the bolt is to far back then that suggests the issue is inside the bolt. With the bolt out of the gun does the nozzle protrude further than it did ? can you push it into the bolt slightly and if so does it pop back out ?

If so strip the bolt again and check that nothing behind the nozzle is out of place . Assuming the bolt is similar to the WE one the nozzle should be all the way back into the bolt and will not push in further.

 

[Nick G]

Another alternative is that the bolt is snagging on something that wont let it go fully forward. Checking the position of the nozzle in the bolt with it out of the gun will help identify if that is the case too. If the nozzle sits correctly fully home in the bolt then the issue is inside the gun (make sure the hammer resets properly) if the nozzle does not sit completely back in the bolt then the issue is in the bolt.

 

[THE CRAB]

Righty, further testing has resulted in catastrophic failure. The nozzle guide has snapped off.

A worn mag catch was allowing the mag to pitch causing the nozzle guide to occassionally bite into the charging handle. Up close what I thought was just normal wearing in on the charging handle definitely wasn't. So that's a new catch, bcg (stripped threads) and handle. Why does it have to be this way VFC?

The bolt being angled could explain why it was struggling to do those last 2mm. Confusingly, this still happened without the mag in, perhaps the bcg or charging handle have deformed due to the excursion. Luckily the upper doesn't seem to be worn. I will take another look at the hammer, thanks for the tip.

In testing I took the front off the upper. Nozzle out of the bcg mates with the hop and receiver extension fine, back in the bcg everything is flush as well.

The mag catch was always very fussy, hopefully this is fixable!