Lath optical 9 in. Rangefinder sight mki
 

I acquired this lath optical 9 in rangefinder sight Canadian Mk 1 with an Adapter bore optical lath. It's NOS complete with case and carrying strap. The bore adapter is 76 mm.
First, what artillery piece would it be for?
Second, how do you use it?

The only mention I can find of a 76mm is the M10 anti-tank gun. They mention field sighting gear in this article so maybe that"s what I've got. Mine is serial number 14.

It had to be used with a field piece because there's no way to see through the turret alongside the gun.
The 17 pdr comes to mind

David,

It will take me a couple of days until I can get my hands on the reference material but I am fairly certain this piece of kit belongs with a CDN 3.2" Rocket Launcher.

Colin

3.2" ???
 

A Heller Rocket Launcher?? Where did they all go??

Remember all the sights Don Smith found in a scrap yard??

Peter S

I still can't figure out why you'd need to attach a rangefinder in the bore of anything.

Hi David,

I managed to get my hands on the 3.2" Rocket Launcher Manual and there is lots of detail on the Range Finder Sight (a complicated device to test and adjust), and your Optical Lath that is used in conjunction with the Range Finder Sight.

Your Optical Lath was designed for 2 functions. When it is attached to the front of the Range Finder Sight it is used to test and then adjust the mechanism of the sight to ensure that it provides the correct range readings to targets. In this mode the sight does not need to be attached to the launcher. The second function is as a bore sight. When used as a bore sight the Optical Lath is attached to the bore adaptor and inserted in the muzzle of the launcher. This assembly then sits at an angle to the Range Finder sight so that the right window of the optical lath is in front of the right lens of the sight to provide a means for zeroing the sight.

I will post pictures tonight (as the function will be much easier to understand with some pictures). I don't know the service history of the 3.2" Rocket launcher but I get the impression that it may have been short lived in the 1950s.

Peter,

I don't recall the sights that Don found as it was likely before my time.

Regards,
Colin

Here are the images:

Here is the text:

Here is one last image from the manual as there are some former QOR forum members who might be interested:

Not quite what I thought it was. Pretty interesting stuff though. So does anyone have a roket launcher that needs a lath optical?