Hi, does anyone know if a fixed stock version of the mech tech carbine upper is legal in nj?

Link to the upper in question?

 

Why do you think it wouldn't be?

http://www.mechtechsys.com/glock.php

 

I'm not sure if it's legal to convert a pistol to a rifle in nj.

It's fine. For example, the Beretta Neos carbine kit is perfectly fine. Just be sure you find something that follows all the rifle laws (barrel must be 16" or greater, etc).

I'm not really up on rifle laws besides, no adjustable stocks, longer than 16" barrel and no threaded muzzle. Is there anything else I need to be aware of?

I'm not really up on rifle laws besides, no adjustable stocks, longer than 16" barrel and no threaded muzzle. Is there anything else I need to be aware of?

16" barrel is a federal restriction, FYI.

 

From Wikipedia, here's the list of "evil features" recognized by NJ:

Semi-automatic rifles able to accept detachable magazines and two or more of the following:

Folding or telescoping stock

Pistol grip

Bayonet mount

Flash suppressor, or threaded barrel designed to accommodate one

Grenade launcher mount

Since these devices retain the pistol grip and clearly use a detachable magazine, you'd be restricted from the other 5 items on the list.

I'm not really up on rifle laws besides, no adjustable stocks, longer than 16" barrel and no threaded muzzle. Is there anything else I need to be aware of?

And stay away from Scary Black. Get it in Pink Camo, and the Weinbergs of the world might not freak out quite so much, it makes it into a "girlie gun".