Front aperture for Brno #4 ?

I wonder if anyone here can tell me where I might find a front aperture set for an old Brno #4 target rifle....The set for my sons' Anschutz don't fit , neither do apertures from aWin. 52,..... Any help would be appreciated..

W44

Got a picture?
If not, what is the outside diameter and are there alignment "ears" on the inserts?

Jim, They are a little smaller than for the Anschutz and a little bigger than the Win...I'll measure for size (as best as I can) and yes, there are two alignment ears ...I have the post insert but I was hoping to find an aperture set....I'll measure soon..

Thanks,

W44..

ps.. I'll try pics as well..