transfer port

Hi guys could anybody tell me the size of the hole on the brass inlet that is on the barrel of a mk1 wildcat , Iam from England and the gun is F.A.C rated just had it away to be sorted it has come back with the action rough as hell , very jumpy on firing ,told by the company that they could only get 40 shots @30 ft ,it has already blown 3 barrel o rings and in the service they gave me they didn't touch the reg or valve just set the reg at 145.

I am very disappointed with this and have found them to be very inEFFECTIVE.

They claim to have put a new inlet on the barrel Just want to make sure it is the right size hole.

Thankyou

Mark 

p.s. this is .22 cal
 
Was promised the gun would comeback has it had left the factory but the more I spoke to these boys the more I found they were full of waffle , the last conversation they asked me to send it back if I wasn't happy but I have had enough of doing that it had already been back to the importers twice and if I told you what they said you wouldn't believe me.

Anyway I think the only chance I have got is to do it myself if that doesn't work bin it !

Never had all this trouble with a gun before and sometimes it has really put me off shooting the way I have been treat , so this is its last chance.

I have had this gun from new the first 2 weeks it was great then problems started went back week later got it back month or so probs again lots of phone calls and being fobbed off eventually went back , got it back with chrono test written by Hans Christian Anderson when it was tested in the shop 80 shots ranging from 28 - 22 fibs , so I then sent it to FXs service and repair specialists and here I am , so if anybody could help me with the measurement I am after it would be most appreciated .