All original barrels fitted ( Which i had/have )to evo's, where and are lothar walther this includes the 1 in 14, same as fitted to the FTP.
Mk1 did have change of stock to laminate, as the silver painted version ( was said by some to have been made from MDF? ) failed/broke.
Ive never had any problems with any of the AA regs or consistancy, the problems that keep getting talked about imo where down to poor assembly and quality control and only on a small number which keep getting mentioned over and over again.
The t-bar filler if found on a mk1 will most definitely be a retro fit, by the owner or by AA if it was serviced by them after the mk2 had been released and mk1 discontinued.
The mk1 barrel ( lothar ) had the brass transfer port because walther at that time could not produce the barrel with a transfer port built in and guarantee its quality/accuracy,
Airarms made the brass fitting themselves ( by hand ).
info directly face to face from source.
The worst fps i had ( all my regs or original and unfettled AA )
mk1= 9 to 14fps over 80+ shots, unweighed pellets
Mk2 = 6 to 9 fps over 90+ shots, unweighed, or 2 to 3 fps weighed
Mk4 = 7 to 11 fps over 90+ from new, first serviced by AA 2 months ago ( 6 years old ) it now does 3 to 6 fps over 90+ shots.
Crashing and burning