That's a great deal on that conversion. I picked one up several months ago and it was 200 plus shipping from MidwayUSA. Mine works great, no fitting required, just popped it on and had no problems with it firing. It ate up all the 22 I tried in it, Winchester m22, Federal champion 525 round bulk box, and CCI AR tactical. Granted these were all quality HV 22 rounds, but I had no issues.
Now, the large frame, on the other hand, I did have some issues. I ordered the large frame conversion from buds for the same price you paid for the small frame conversion. It fit right on either of my match model lowers, but could not get the darn thing on a standard large frame 9mm. It was go on, but it was hanging up if you tried to cycle it. It had more jams than the small frame converion did.
Anyway, I probably need to smooth some of the edges or rails or something on the large frame conversion, but the small frame converison functions very good.
Darin.