Broke my trunnion welds today in my FA Vector.

[thompson4433]

Noticed that the barrel nut wasn't engaging the retainer button.

Turns out the trunnion was slid forward about 1/8".

Broke those trunnion welds under the handgrip somehow.

I bought the Vector NIB and picked it up in February, fired probably around 3000 to 4000 rounds of 9mm so far and maybe 2000 22LR.

Now I have to send it out for repair.

I guess this will be a chance for me to start shooting some of my other guns again, I've been shooting the vector almost exclusively since I got it.

 

[thompson4433]

Well I guess this will be a chance for me to have anything out of kilter to be bought back up to proper spec.

And get a machined feed ramp installed.

I wonder if this was caused by some sort of alignment problem.

 

[Kuglespritz]

Sorry to hear about the weld break!!!! Would you mind posting some pictures? I would like to see exactly where the break occurs.

 

[kaen3e]

Been there twice. One was at UT5. Back when we had shoots. Send to Richard at bwe. Vector put mine in crooked the first time

 

[thompson4433]

not really much to see

the trunnion is held in place by 4 plug welds through the frame under the handgrips

so now the trunnion is loose, can be pushed forward and backwards

probably the plug welds did not have adequate penetration and sheared off inside the receiver

the welds don't look any different from the outside

 

[UZI SBR AWC]

You in Ohio ? Local fella that does weld work for a C2, he does TIG, Micro TIG, and Laser weld...

 

[Vegas SMG]

Welcome to the club. The trunnion welds broke on my NIB Vector at about five hundred rounds. Vector rewelded the trunnion but the gun was never the same. Blew out the rear backing plate twice.

 

[thompson4433]

Blew out the rear plate twice?

Hmmm....

Well I suppose you really cannot attribute that to anything other than bad welding


I guess I'll send it off to an UZI guru and get it done right

I'm a little irritated but you run into these u-turns from time to time.

I was lucky enough to buy this gun NIB for $8000 and it's worth probably $10 or $12K

soon to be $20K?

who knows

anyway it's worth a little welding and TLC

plus my subgun ord 22 kit is running 100% now

 

[couch commando]

I'll bet that they MIG welded the trunnion. When I built my first AK, I mig welded the trunnion in the receiver. It broke after only 40-50 rds. I took it to a friend who had a tig machine and he welded it. about 7-10,000 rds later it's still shooting.

 

[Vegas SMG]

Blew out the rear plate twice?

Hmmm....

Well I suppose you really cannot attribute that to anything other than bad welding.

A number of Vector Uzis were welded incorrectly in the early days and broken trunnion welds weren't uncommon. The rear backing plate was only the 2nd one Rex had seen at that time and he grilled me about the ammo and calibers I'd been shooting. Nothing besides thousands of rounds of commercial 9mm and many bricks of .22LR with the Vector conversion. The backplate repair lasted a few hundred rounds before it broke once again. These and other problems resulted in me losing confidence in the gun and I sold it with complete disclosure of all problems and repairs.

Most Vector Uzi owners will never put the number of rounds down range that I did, and most will never have a single problem with their guns. Having been there and done that, I'd never buy another Vector Uzi. I want a real Uzi with a receiver that's in spec, and unfortunately the Vector gave me heartburn I'll never forget.

I've always missed owning an Uzi, and I recently picked up a Group Industries conversion of a model B IMI Uzi with the blocking bar removed. I'm happy to have another Uzi and I should have it in about a year... If BATF transfer wait times don't get any longer.

 

[thompson4433]

I cannot see any reason why the backing plate welds would fail unless the weld was done poorly. A properly done weld should at least match the base metal ultimate strength and there are not going to be enough load cycles to make fatigue an issue until you get to around 100,000 round count.

if you said the base metal failed due to embrittlement, then sure I would say blame the Vector receiver, but otherwise from a logical standpoint the fault would lie with a bad weld, full of air bubbles and slag

According to the American Society of Mechanical Engineers (ASME), welding defect causes are broken down as follows: 45 percent poor process conditions, 32 percent operator error, 12 percent wrong technique, 10 percent incorrect consumables, and 5 percent bad weld grooves

Note that it doesn't say, "the name stamped on the side of the gun"

 

[Vegas SMG]

The poor trunnion welds were blamed on a welder who worked for Vector in their early days.

I posted photos of the back plate but unfortunately they were deleted with many others to fix a problem with the site. There was poor penetration with little weld showing after the area was was ground clean.

 

[Vegas SMG]

http://www.uzitalk.com/forums/showthread.php?8818

 

[delta-10]

Damn, I haven't heard of this happening to uzis that much. I have a converted IMI model B with the blocking bar removed and the barrel restricter ring removed as well. It runs like a champ. I have put approx 3000 rounds through it so far plus another 1500 or so with the subgun ordinance 22 kit.

 

[thompson4433]

You in Ohio ? Local fella that does weld work for a C2, he does TIG, Micro TIG, and Laser weld...

I'm in PA. Ohio is a good 8 hour drive.

Thanks anyway.

I'm going to send the gun off to an UZI expert and have him give it the once over.

 

[thompson4433]

The poor trunnion welds were blamed on a welder who worked for Vector in their early days.

I posted photos of the back plate but unfortunately they were deleted with many others to fix a problem with the site. There was poor penetration with little weld showing after the area was was ground clean.

It's too bad the photos are gone, I would have liked to have seen them.

I'm not an expert on welding sheetmetal but I am a structural engineer and I know plenty about welding plate steel.

I noticed that one of the posters in your old thread recommended giant welds. Just as an FYI to anybody reading this, giant welds are more trouble than they are worth. When weld metal cools, it cools unevenly and the contraction during cooling sets up huge residual stresses and can even crack the weld.

 

[Kuglespritz]

It's too bad the photos are gone, I would have liked to have seen them.

.

Yes, photo's are helpful

 

[Garrett]

I thought I had a picture from when my trunnion welds broke, but I can't find it now. As noted, there was nothing externally to see on the welds. There is a flange at the front of the trunnion that butts up against the front of the sheet metal receiver. Mine moved to where there was maybe a 1/8" gap between flange & receiver. The trunnion was still in there solid, so while I had noticed the gap I wasn't sure if it had moved or if it had originally been welded there.

It turns out it was still slowly moving forward as the bolt would smack the rear of the trunnion. It finally got to the point where it moved far enough forward the bolt was hitting the tapered section at the front of the receiver. It then stopped working (firing pin not contacting the primer) and I realized something was wrong.

I ended up sending it to BWE for repair. I used this excuse to get a feedramp installed as well. The work was first-rate, and the gun runs great now. Turn-around time was longer than quoted, but the end result was worth it.

 

[eyegun]

A friend of mine blew his back plate out about two years ago while shooting it.

Vector fixed it.

I have lots of pictures but these show the deal.

 

[thompson4433]

Are there any tip-top UZI gunsmiths that don't have a 6 or 9 month backlog?

hate to see the last of this gun until next July