I have some about 400+ of the 220gr SMK sitting in the garage not being used. PM me if you want them. Price will be Powder Valley new price adjusted for what is left + shipping.
I bought some new tubes last year and my shooting buddy got some from Nationals this year of the new tubes. They did not require any modifications to fit in an STI gun and all of his dropped free. Mine needed a little adjustment on 2 of the 6 to drop free. On my older set of "NEW" SVI tubes that I sold, they had to be modded quite a bit to work. YMMV.
With regards to the SIRT - I had a Range Safety Officer come up to me once and asked me to unload and show clear when I was practicing with the SIRT pistol. So declaring it to a TSA agent makes sense since they look so real.
I had this on a SJC17 Open Glock, I kept hitting it when I gripped the gun every now and then. Needless to say, the mag fell out. Eventually, I took the thing off. YMMV
The Vortex (25oz) is also much heavier than the Z6i (16oz) and it is amazing what a 1/2 lb difference can make to handling. For glass and clarity, you should check both out.
I made this choice as well and shot this way for Area 2 last year. The net result was 3 Deltas and no Mikes or No Shoots with 96%+ of the points. I think I enjoyed it more than when I was trying to go fast.