the screws i suggested above should sort the problem
once they strip the thread [go round and round]the screw will never countersink or do any good
That makes sense, I'll pick some up asap and hopefully that will resolve the problem. Appreciate your help, many thanks.
just been out and screwed 3 off the screws i suggested into 6mm ply and 21mm pine
crisp clean easily screws self countersunk no hint off striping
as an aside you need a pz2 bit not a ph2