Nice pistols and well done on the photography.
I have never handled one of these, looking at it I presume the barrel is concentric with the piston which makes for a compact design. They look very nice and would love to have one some day. I believe these (or a similar design) were available new in the UK in the 80's, but I stand corrected on this.
Phoenix Arm's produced the Sporter and the target, Still marketed as Hy-Score Arm's Company but I believe manufactured in Sandwich Kent under the Phoenix banner, The UK Sporter however differed to the shorter US version although still with interchangeable barrels and still a very nice pistol, One of my favorite's.
Steyr LP10, Steyr LP5,
Vintage Collection - Walther LP53, HW77k Venom, BSF S20 Match, Original 35, ASI Target plus lots more