Parker Hale 1200TX receiver sight thread question

[dan belisle]

Picked up a PH 1200TX a while back. Just got around to mounting a scope and noticed the rear scope mount threaded holes seem to be a slightly different size/pitch than the front screw holes. Anyone run into this before? Any idea on the hole size? - dan

 

[Hitzy]

6-48 and 8-40 are the 2 most common. Usually if 6-48 strips it's opened up to 8-40.

 

[Potashminer]

Parker Hale was British made - could easily be BA threads - if I remember, the #4 BA is .142" x 38 1/2 threads per inch - nearly exactly half way between a 6-48 or an 8-40 that we commonly use. However, the Parker Hale bases that I have all seem to come with 6-48 screws.

 

[dan belisle]

6-48 and 8-40 are the 2 most common. Usually if 6-48 strips it's opened up to 8-40.

It’s smaller than 8-40 but bigger than 6-32. I guess I’ll just open it up to 8-40 and drill the mount holes slightly larger. Thx. - dan

 

[Potashminer]

I did the same on a recently acquired home-done conversion of a M1917 - oddly enough, the screw that originally holds the rear sight spring is #4BA - I fully threaded that size screw all the way through with just my fingers. Previous owner had used it as one of a pair to install a rear scope base - had installed a #6-48 that was simply stripped. Got it exactly aligned and re-drilled and re-tapped to 8-40 - that cleaned out the #4BA threads nicely and an 8-40 torqued up to proper spec.

 

[Lee Enfield]

The rear holes are BA.

2BA or 4BA i can't remember off hand.

 

[dan belisle]

The deed is done. Had to open up the holes in the mount, but now it's secured with 8-40. Little Loctite and we're good to go. - dan