Looks like your Galloway is pretty close to 1.58-1.59mm longer than the stock.

I re-measured my stock piece at 28.52mm using my great digital caliper given to me by an old friend some 6 years ago. [Same number I got 2 years ago, even after a recent battery replacement.]

I also re-measured the NDZ piece, in situ, and got 29.50 mm.

The final answer seems to be that the Galloway is ~1.58mm longer than stock and the NDZ is .98mm longer.

I did select the Stainless NDZ version because it gave a little bling, very little, to the frame. I like the NDZ because it is Laser cut and machined instead of stamped, and while long enough to do the job, is not long enough to bother a holster, if I ever get a holster.

(My measurements can be "jiggered" about .01mm depending on how I hold my tongue but they are pretty consistent within that range.)