Click HERE for a picture of the adapter that I am talking about.
The V. M. Hy Tech magwell adapter allows unaltered UZI mags to be used in an M-16 adapted to 9mm. It inserts into the bottom of the magwell and is held in place by the original mag release button. Releasing the back push pin and "breaking" the AR/M-16 open helps get the adapter fully seated up into the magwell/receiver.
It is a well engineered and quality made aluminum insert (the ejector and magazine release button are steel of course) with very tight tolerances and a nice even black andonized finish that matched the host firearm closely. I have seen another unit beside mine and the second was also a well made and very close tolerance unit.
The spring on the release button is strong and it holds the mag securely, requiring a firm and deliberate push on the mag to seat the mag past it and a firm and deliberate push on the release button to free the mag. Some mags that I used were very tight in the magwell and a break in period is going to be required before all of my various make UZI mags will slide in smoothly.
I knew up front that using unaltered UZI mags would preclude any bolt hold open feature. That took a little getting used to, mostly when trying to seat mags positively into the magwell.
The one drawback that I encountered was that the mag release button is flush with the insert block so it is hard to find by "feel" and it needs to be pressed deeply into the block to release the mag. I plan on adapting a large button head safety button or AR/M-16 mag release button to raise the surface and ensure proper depression and release of the UZI mag. If you are a competetive subgun shooter you will want to rework this area for sure to speed up your mag changes when using this magwell block.
Contact info for V.M. Hy Tech is below.
V M Hy Tech
1217 W Hatcher Rd
Phoenix, AZ 85021-0512
V. M. Hy Tech
(Edited to add that I didn't realize that there was a thread already started on this below.)