At one time I shot a Remington 40X equipped with Freeland tube sights. They were popular in the 50s & 60s. If the sight is in good shape, they worked very well, equivalent to some of the Redfield sights. From my notes, I found the following:
Remington 40 XB (1962 vintage) had a heavy barrel, is stamped “US/.22 long rifle” above the s/n. The Al Freeland tube rear sight is 1" dia. and came with 1 aperture; it has standard Redfield/Lyman threads so it is easily interchangeable. The sight comes with Unertl standard bases. The sight & bases are in VG condition.
The matching Al Freeland tube front sight is also 1" dia. & comes with 1 aperture. It is in VG condition.
I attached some pictures s you can see what it looks like.
Bear in mind that the tubes on my rifle were 1" dia. Are you sure the one you are looking at is .75"? A Merit aperture should fit. I never tried one but the threads should be the same.
We ain't come this far just to dump this thing in the drink. What's the nearest target of opportunity?
- Maj. Kong