You may be able to find one on Gunbroker.com. I bought a couple of frames there over the past few years, and they weren't very expensive. I was kind of hoping I'd find P80 making a 43X frame, but no luck so far. Here's one on Gunbroker: https://www.gunbroker.com/item/934653979
https://www.galleryofguns.com/genie/PowerSearchTabView/SearchResultsMags.aspx?&mfg=Tikka&material=All&capacity=All&series=All&cal=All&zipcode=30607
The link above may help. I have seen some in stock through a few distributors, but I'm in Athens, so it probably wouldn't be very helpful to you...