Magazine Questions

Are Canik and Walther Magazines interchangeable?

"Since the Canik TP9SF magazine is identical to the Walther PPQ m2 9mm mags and can be fired without any issues and are 100% interchangeable then your extensions should work on either. Am I correct?" 

No. While Canik mags may function in a PPQ, the Canik mag is slightly narrower. As a result, the basepads are NOT interchangeable.

HOWEVER: The new Walther PPD full-size (emphasis on full-size) uses an 18-round mag tube that is nearly identical to the Canik (the mag catch notch is slightly deeper). You could use that magazine with a Canik extension on it in a PPQ -- but not a PPD!

Why? The PPD frame has a pronounced "tail" that comes down below the end of the mag tube. If you try to use a Canik basepad on the PPD, the bulge on the back of the mag (that houses the screw) will hit the "tail" of the PPD frame.

To fix that, we made PPQ-style +4 basepads for the PPD (with the flat plate on the back).

The PPD +4 basepad will fit on a PPD/Canik mag tube, and THAT combo can be used in a Walther PPQ, Walther PPD (either size), or a Canik (all three sizes). 

 If you add magwells to this discussion, things get even more complex.

Why does my Goliath magazine extension not add enough extra rounds?

What you're going through sounds exactly like what happens when people are running typical range ammo like the popular "Winchester White Box" in a Goliath.

Winchester (and some other brands) load to 1.160" -- which is the upper end of the SAAMI specification. That stuff NEVER works -- the bullets rub on the front wall of the extension and hang up exactly as you describe.

Federal tends to load shorter -- to about 1.145" -- and it typically works great. Josh Froelich wins PCC matches from sea to shining sea shooting Federal Syntech out of our Goliaths and a JP-5 and/or GMR-15 rifle.

I've had good luck with Fiocchi 124s, which tend to be around 1.125". We've been told by customers there is some batch-to-batch variation in Fiocchi (could be between 115 and 124 grain weight?), so double-check before you buy Fiocchi in any quantity.

For now, try some Federal Syntechs and see what happens!

Differences between Uzi and Colt-Type Magazines

Colts have a track up the back for a bolt-hold-open device. UZIs don't.  See picture