Hey folks, I'm looking at getting a Williams peep for my Austin and Hallek 420 that will mount in the scope mount holes like most of them do. However, They don't list one for that rifle and I know that the Knights have a round receiver like the A&H does. If one of you bighorn owners could measure the dia. of your receiver I could compare it to my A&H and see if the same Williams sight would at least fit on the receiver. And I did call Williams customer service, but haven't got an answer yet from them. Thanks in advance.