Ok then i have to shoot it empty and check the valve. Maybe they made a mistake and build in this valve stem:http://www.airgunspares.com/store/product/16162/BSA-BSA-Buccaneer-K-Off-Valve-16J-Part-No.-16-9145/
Ok the hole of the backplate is about 5mm, one more than the transfer port. If the hole would be bigger, then the valve spring would go through.. Also i should have the valve stem vor the FAC version. I think i`ll write bsa an email...
But How I measured the stock MK valve throat was to use a sharpie pen cap... being raised seat instead of recessed like The BSA it left marking on the plastic when I triwled it a bit with slight pressure...
Could you tell me how much hammerspring preload do you have on your rifle?
Valve tunnel should be 5.2mm to match the TP and valve block outlet should be 4mm.
I don't know if there's enough material on TP to drill out that block outlet though,
those o-rings seem to be rather close. In old style PCPs you could drill the TP to 4.5mm easy and even make the bottom conical to match 5mm outlet in the valve block.
Sorry for late reply! Quote Valve tunnel should be 5.2mm to match the TP and valve block outlet should be 4mm. Which area of the valve is called Valve tunnel? I think the outlet of the valve is the area which is labeled with red in the above picture. If i am correct then the inner dia of outlet valve and the inner dia of transfer port is same i.e 3.85mm. QuoteI don't know if there's enough material on TP to drill out that block outlet though, The wall of the TP is 1.1 mm thick. Plz see the picture belowQuotethose o-rings seem to be rather close. In old style PCPs you could drill the TP to 4.5mm easy and even make the bottom conical to match 5mm outlet in the valve block.It is BS009 O-ring and it has 5.28mm inner dia . So i think it can be drilled easly.
Valve block exit is that one marked red that feeds the TP. The exit and TP should be matched to barrel port (hole that feeds air in the barrel) and that's 4mm in normal BSA .22 barrels. Make sure that the probe holes are also 4mm. That leaves the valve tunnel which is the horizontal tunnel in the valve block right after the valve seal. Air goes through that to enter the TP via valve block exit.