Weihrauch HW45 Beeman P1 in .20 with .177 barrel, folding stock

This mid-1990s Beeman P1 branded Weihrauch HW45 comes with the factory .20 barrel installed, aftermarket Colt 1911 grips, a spare .177 barrel than can be installed in minutes using an Allen key, a new folding wire stock and installation hardware from Germany, and a small tub of .20 H&N Field Target Trophy pellets. It sports the old style, solid iron sights, not the newer fiber optic sights.
I have tested this pistol and it cocks, loads, seals and shoots with both barrels. The sear is in good shape and the trigger and rear sight maintain their full range of adjustment. It is selective about pellets but handles .20 H&N FTTS just fine. It was modded by a previous owner, who installed a Tinbum tuning kit to smooth out the shot cycle and lower velocity to keep the .177 barrel legal. I don't have a chrony but I have another HW45 in .22 and have shot HW45s in factory .20 and factory detuned-for-Canada .177, and the power on this pistol seems low to me. It should be a 25 or 45 yard target gun, but in its present configuration, it isn't, and I've priced it accordingly. The only modification I have made is to restore the two OEM barrel keeper screws.
If I were going to keep this airgun, I would strip it, clean it, change the seals and test it again; and might even replace the Tinbum kit with an OEM mainspring and hat to bring it back to full power. I have not installed the folding wire stock, but putting it on is a simple matter of knocking out two pins, and the instructions are easily found on youtube. If you turn it into a pistol carbine, you'll want a scope or red dot because the point of aim changes significantly once all the recoil is taken out of the equation. It was scoped once because there is a mark from the scope stop screw in the top of the receiver. It was not a safe queen, and there is typical finish wear in the usual places. 
If you've used one of these before, you know they are great pistols. With a tuneup to bring it back to full power, it will still be shooting 30 years from now. $575 shipping included or $550 local sale. No RPAL needed but must be over 18.