Transfer Port Diam' HW90

[manxteddy]

Have been reading some articles about opening transfer ports on HW Springers amongst other things to smooth-out shooting, can anyone please tell me the transfer port diameter on an FAC 'ed HW90 .I do know that a greater airflow is availble due to increased stroke length.Will this spoil a 12ftb rifle ? Or make it smoother ?
Graham

[DM80]

Have been reading some articles about opening transfer ports on HW Springers amongst other things to smooth-out shooting, can anyone please tell me the transfer port diameter on an FAC 'ed HW90 .I do know that a greater airflow is availble due to increased stroke length.Will this spoil a 12ftb rifle ? Or make it smoother ?
Graham

my own experience of opening the ports on HW's springers is if they are opened more than 3.5 mm they shoot cr@p with very sharp harsh recoil' 3.5 mm is spot on though but gas pressure or spring pressure will need to be reduced to keep it legal if port is opened to say 4mm i've found its the opposite' spring or gas pressure needs to be increased just to get it near the legal limmit' thus the higher recoil & harshness.

Dave.

[manxteddy]

Thanks Dave for your prompt reply.By the way the Original Model 10 I told you about some time ago is going well at the moment so I guess it does not need a service....just yet !
Famous last words
Graham