Screw sizes for scope mounting blocks!

[Chief1966]

I have a Winchester 1885 single shot rifle that has four screw hole that I would like to fill with plug screws.
I have tried 6-48, 6-40 and 6-32 screw plugs and neither will go. What are some of the other sizes that were used?
Thanks!

 

[jackieschmidt]

Brownell sells the mount with 8/40 screws.

 

[Chief1966]

Brownell sells the mount with 8/40 screws.

#8 screws are larger in diameter. #5 would be a size smaller but never heard of anyone using them for anything.

 

[Walt Krafft]

Are #6 screws too big or small? What diameter are the holes? Are the edges of the holes rolled over?

 

[Ggmac]

are they in the side of receiver or on the barrel ?

 

[Chief1966]

The screw holes are on top of the bbl.
The # 6 screws are to big for the hole. I can just get them started enough to take hold but didn't want to force them in the hole. The holes and the threads were cleaned, so no debris are in them.
I did consider getting a 6-32 tap to make sure the edges were to par. Probably my next move!

 

[Walt Krafft]

I really doubt they are 6-32. 6-40 or 6-48 are much more likely.

 

[Chief1966]

I kind of thought that also. I know 6-48 is kind of the standard now but the gun was made in 1887 and I have no idea when the holes were drilled and tapped.