Model A: Point of impact beyond max. sight windage adjustment.

[zwo_a_vier]

I've run into a strange zeroing issue with my Action Arms Model A.

Brief background: The gun is an IMI made Action Arms Model A with 10,2" barrel and a 2" pinned flash hider to comply with our legislation (11,82" to qualify as a rifle) with a new I bought the gun four months ago and took it to the range.

The sights were not spot on, but I was able to get them dialed in and the gun performed adorably from 50 meters, 75 meters and 100 meters. Few weeks after that I attended a 3-Gun reservist action match with the gun, and again performed comparably good against AR's and AK's. Lovely gun indeed :uzi.

But now for some reason that I've yet to figure out, the gun has started to shoot left. Even so much, that I struggle to hit classic IPSC targets from 50m.

Took it home and dismantled the gun to check whether the trunnion spot welds have gone lose or there was something else going on with the gun. I found nothing. Did thorough cleanup and oiled moving parts.

Two days ago I took it to bench and started adjusting the front sight at 50 meters (54 yds). The results were not satisfactory. Front sight is now fully deflected to the left, but point of impact is still some 5-6 inches to the left.
The groping, instead, is amazing, the gun easily shoots 1,5MOA with 115gr 9mm bulk ammo.

I'd really appreciate your experienced input into this issue. I do not understand what could have happened. I frequently remove and reinstall the barrel to get the gun fit into my smallest SBR bag, but this has not caused me any issues before. The only change I've done to the gun, is that I've replaced the top cover with a German army surplus one - as I am planning to use that very same cover for optics installation in future. I've yet to try again with the original cover, but could this really cause the issue? Personally I find it hard to believe.

Br, Joonas

 

[MPA guy]

A lot of people get into this with suppressors changing the point of impact too.

It can be caused by too tight of a bore. Though those issues more often cause erratic shotgun patterns due to slight destabilization.

Threading of the barrel or threading of the muzzle device not being perfectly straight may be causing the gas to deflect the bullet over to one side.

Or, if it's welded, perhaps too much heat warping the end of the barrel.

I don't personally have any experience changing top covers so I'll let someone else answer and address that.

 

[zwo_a_vier]

A lot of people get into this with suppressors changing the point of impact too.

It can be caused by too tight of a bore. Though those issues more often cause erratic shotgun patterns due to slight destabilization.

Threading of the barrel or threading of the muzzle device not being perfectly straight may be causing the gas to deflect the bullet over to one side.

Or, if it's welded, perhaps too much heat warping the end of the barrel.

I don't personally have any experience changing top covers so I'll let someone else answer and address that.

That'd all makes sense, but the gun shot flawlessly with the very same muzzle device earlier. I just cannot root out that what has changed.

 

[Starvingboy]

... that time you knocked the gun off the table onto the concrete, and forgot about it until I mentioned it? (No idea if that actually happened, but thought it worth a try)

 

[zwo_a_vier]

I really hope that I could recall such incident happening, as it would give me some reason and explanation for the issue on hand. Everything feels super rigid, the barrel nut has all the teeths intact and so on. Any ideas would the B-model rear sight parts fit in without permanent modifications to the gun? That'd be worth a try.
Too bad these guns are super rare up here. Would love to try out wit another barrel.

 

[fortyfive1911a1]

Was the barrel removed from the time it was shooting accurately versus when it started impacting to the left? Did you change ammo?

 

[zwo_a_vier]

Was the barrel removed from the time it was shooting accurately versus when it started impacting to the left? Did you change ammo?

Yes, I have frequently removed the barrel from the gun - I've always been under impression that the UZI quick detachment method keeps the zero well. I did this even when gun was dialed in, and run into no issues at all. I have tried the gun with three different sorts of ammo- 115gr, and two different 124gr (including the the ones that did shoot straight initially), and the differencies seem to affect elevation mosty - not windage. My idea was to check whether there's crud, sand or some other FOD on the mating surfaces of the barrel and the trunnion, but found nothing and the issue remains after a full cleanup. Detaching and attaching the barrel between strings of shots do not change the POI.

 

[zwo_a_vier]

Here's the mentioned deflection from 50m. Point of aim in the center.

 

[sniperdoc]

Put the original top cover back on and try it.

 

[bigu2fan]

I've run into a strange zeroing issue with my Action Arms Model A.

Brief background: The gun is an IMI made Action Arms Model A with 10,2" barrel and a 2" pinned flash hider to comply with our legislation (11,82" to qualify as a rifle) with a new I bought the gun four months ago and took it to the range.

The sights were not spot on, but I was able to get them dialed in and the gun performed adorably from 50 meters, 75 meters and 100 meters. Few weeks after that I attended a 3-Gun reservist action match with the gun, and again performed comparably good against AR's and AK's. Lovely gun indeed :uzi.

But now for some reason that I've yet to figure out, the gun has started to shoot left. Even so much, that I struggle to hit classic IPSC targets from 50m.

Took it home and dismantled the gun to check whether the trunnion spot welds have gone lose or there was something else going on with the gun. I found nothing. Did thorough cleanup and oiled moving parts.

Two days ago I took it to bench and started adjusting the front sight at 50 meters (54 yds). The results were not satisfactory. Front sight is now fully deflected to the left, but point of impact is still some 5-6 inches to the left.
The groping, instead, is amazing, the gun easily shoots 1,5MOA with 115gr 9mm bulk ammo.

I'd really appreciate your experienced input into this issue. I do not understand what could have happened. I frequently remove and reinstall the barrel to get the gun fit into my smallest SBR bag, but this has not caused me any issues before. The only change I've done to the gun, is that I've replaced the top cover with a German army surplus one - as I am planning to use that very same cover for optics installation in future. I've yet to try again with the original cover, but could this really cause the issue? Personally I find it hard to believe.

Br, Joonas

Do you have a spare barrel to try in your gun? Or, can you try your barrel in another Uzi to see if the same windage issues occur in the other Uzi?

 

[Seven Clicks Up]

Put the original top cover back on and try it.

That's what I was thinking. Go back to when it was good, and figure out what you have changed.
Maybe the new top cover is having a detrimental effect.

 

[zwo_a_vier]

Put the original top cover back on and try it.

Tried today, unfortunately no effect - the POI remains the same.

Do you have a spare barrel to try in your gun? Or, can you try your barrel in another Uzi to see if the same windage issues occur in the other Uzi?

I know a guy who owns semi-auto conversion, open bolt gun. I have no idea whether his barrel would fit, but we'll give it a try.

 

[sniperdoc]

Scrub the Barrel (inside and outside), the Trunnion, and the Barrel Nut with a good Solvent; there may be something you didn't or couldn't see.