No need to change the slide just a conversion barrel and g-17 mags. Lone wolf and others have the barels for 130 or so.
Except, they are Backordered, for about 6 months at the moment.... I called last week, and got on their Dealer List.... they are swamped...
I finally received my Lone Wolf G29 10mm to 40 conversion barrel a couple days ago. Only took 4 months, ha, and I ordered it in October before the frenzy. The G20 conversion barrel I ordered at the same time only took a month, must have got lucky. I'll update my range report soon to include the G29 barrel.