Mike D on German tunnel front sights

Mike D on German tunnel front sights 

With thanks to Mike. He says:

This photo shows two familiar vintage German front sights. They consist of three basic parts: a tunnel that clamps to grooves at the muzzle; the sighting element as a flat metal insert; and a threaded sleeve that clamps the insert into the tunnel.

Over the years, German sights evolved three different standard thread sizes for the sleeves, which interchange between makes, and enabled aftermarket accessories to be developed. The earliest size was M17 (17.0 x 0.5mm), still used by Diana and Weihrauch on sporting rifles. Anschutz later developed the slightly larger M18 (18.0 x 0.5mm), still common. Today most new top-line 10-meter guns use a yet larger M22 (22.0 x 0.5mm).

Now here is where some confusion comes: THE SLEEVE THREAD AND METAL INSERT DIAMETER ARE NOT RELATED. In this shot, you see the tunnels have an internal "shoulder" - slightly smaller in diameter than the sleeve thread - into which the insert nests:

Thus sights can share accessories, but the metal inserts are proprietary to each manufacturer, with different diameters and side tab patterns. To illustrate, here are some I have on hand:

Walther developed the M17 thread in the 1950's, and Diana and FWB copied their insert pattern verbatim (though the latter is an M18 tunnel). Aftermarket accessories are no longer made for M17, but each of these makers does have some unique element shapes.

As far as I know, no other manufacturer has used the Weihrauch insert pattern. Shooters are limited to the same half-dozen elements they have supplied for many years.

The Anschutz inserts - easy to identify by the asymmetrical tab pattern - are used by many other manufacturers. They made a wide variety of insert elements, and a great many aftermarket inserts and other accessories are available. Anschutz tunnels fit perfectly centered on Weihrauch barrels, by the way...

For quite a few years, Diana, Weihrauch, and Anschutz used front dovetail grooves spaced at about 9mm. The Anschutz sights, which clamp via a small steel sliding "foot," are tolerant of minor variations, and fit all three brands easily. But Diana and HW sights, which clamp by actually flexing the body of the tunnel, are hinky and often refuse to cooperate. (Top to bottom in pic - Walther, Anschutz, HW)

Thomas adds:

It should be noted the width of the dovetail groove varies on these guns as well such that the tunnels themselves don't interchange from brand to brand.  The Chinese XS 28 sights from Flying Dragon will interchange with the old Diana dovetails.