I bought two 170’s off their website a few years back, before going to nationals. I didn’t have time to test them before but I thought new SV magazines would run in my SV. I loaded them up and found out that they only held 26-27 rounds. Ok, I’ll use them on the shorter stages or where I am going to reload early. They both had FTF issues the first time I used them. I set them aside and didn’t use them for the rest of the match. When I got home I figured out that the springs were too weak. Grams springs and followers fixed that. Also when I put them in a magazine gauge, I had a few MM to spare so I went with a larger base pad. They now hold 29, reloadable.
I would recommend that you build your own 170’s or buy MBX magazines. If you do buy from SV, make sure they know what you want: maximum capacity that is reliable that barely fits into the gauge.