Screw pitch

[Ishodu]

I have a set of weaver mounts here to install a scope on my Mossberg 835. I can't seem to figure out what thread the screws are that holds the mounts to the the gun. I think its 8/38 but its quite odd ball. If it is anyone know where to pick up the correct tap?

 

[sunray]

No such thing as 8/38. 8/48. Measure the diameter of the shank and post it here, One of us can give you the proper drill and tap number. Try any decent hardware store or Princess Auto for the tap.

 

[gunasauras]

Very likely 6-48 which would need a # 31 drill.

 

[Ishodu]

Its not a #6 for sure, its too big, I will measure today. I have tried screw pitch gauge 36 and 40. 40 seems to be too fine and 36 is to coarse. Also .7mm is close but no fit.

 

[tiriaq]

6-48 and 8-40 are the most common scope base screws. I am unaware of Weaver using anything odd, but anything is possible. I am not familiar with the 835. Does it have an aluminum receiver? If so, be very careful. The threads have to be good. The holes have to be properly aligned as well, of course.

 

[guntech]

I have never seen an American made gun that did not use either 6x48 or 8x40 threads for scope mounting bases.

Why not try http://www.mossberg.com/faqs.htm

 

[Ishodu]

Well Turns out its metric!!!! I measured the screw to only find that it measured exactly 4mm to the hundredth. And since .7mm pitch was about the closest I just took a piece of scrap metal and tried a hole. The screw goes in nice and snug.