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-   -   M82 scope reticle question (http://forums.thecmp.org/showthread.php?t=255132)

sonnyboy 11-19-2019 01:49 PM

M82 scope reticle question
 
In my weaver 330 scope, when I adjust the POI several clicks, the recticle sits higher in the field of view. I never knew that!!!!. I thought the crosshairs stayed centered when adjusting for POI....In my M82 lyman scope, the post seems very high in the field of view when I had to adjust for POI with new mounts. Is the lyman scope recticle also rising up higher when adjusting for elevation in the field of view?? If so, then shims an adjustment windage screws on redfield base is in need of fine tune alignment adjustment for maximum recticle centered placement...............How do lymans work ????

Mike in Wis. 11-21-2019 11:16 AM

Most scopes didn't have optically constantly centered reticles until around 1956 or so... in the civilian world, I think Weaver was the first to offer them in the K-series 60B scopes. On the previous scopes in military usage they used shims to attempt to bring the cross hairs "close" to center of the adjustment range and fine tuned using the scope adjustments. On the M1D they filed material off the mounts contact surfaces to attempt to center at times. All they wanted to do was get close as practical so as not to use all the internal adjustments or shoot with a very limited and distracting reticle position. If you are using a M1903A4 they installed one of several thickness shims under the front ring mount. IIRC there were 4 different thickness shims They are needed on most if not all A4's to level the base so the scope would zero at say 100 yards and still have enough adjustment for 600+ yrds. The available front shims were generally .020 or .015,....010 and .005 were also available. On occasion 2 shims were used. The rear adjustment on the Redfield mount was employed for rough windage correction. Most of the repop M82/M84, M73B1 scopes have optically cenered reticles... sort of an advantage in a way. :-)

sonnyboy 11-21-2019 01:25 PM

scope mystery solved
 
Mike, thanks for your thoughts on my scope misalignment crosshairs. My M82 scope has its post 3/4 from the top of the sight picture. My weaver 330 after removing the m82 was installed an the crosshairs after clicking the heck out of it, rested high in the FOV. Like the cross, higher up. So, I went on line an bought a M84 which was supposed to be more advanced, installed two shims (a .20 an a .15)slide them under the front base an replaced the screw an at 100 yrds can keep the shots on a quarter size. I guess I have all kind of possibilities now that I have one of each type of scope. One more question, on the m84 I zeroed it in for 100 yrds an loosened an placed the 100 elevation dial marker on the metal indicator tab an tightened up the larger outside nut to keep the position. If I want to shoot to 200 or 300 yards, do I turn the dial to 200 or 300 to have correct allowance? or is the graduated dial indicator only to give you a reminder of the starting yardage setting. I think I read that each click represents 50 yards, so adjusting from 100 yards to 300 yards I would need to give my elevation clicks 4 up........right??? not set the dial to 300..........that would be too much..................sonnyboy

Herschel 11-24-2019 04:29 PM

The click value on scopes is in minutes of angle, not yards.

A minute of angle is roughly 1 inch at 100 yards. Earlier scopes had half minute clicks.
Later one are commonly one fourth minute clicks. If you were hitting two inches right
at 100 yards then it would take two minutes left to get you centered on the target
if your scope, or micrometer rear sight, had 1/2 minute clicks. I am sure someone
will chime in and explain how much a minute of angle is at 100 yards but the old rule of
thumb that it was 1 inch at 100 yards was good enough for target shooting. At least
it was acceptable back in the days when I fired in hipower competition with the M1 and M14 rifles.

Mike in Wis. 11-26-2019 12:33 PM

Quote:

Originally Posted by sonnyboy (Post 1887645)
...on the m84 I zeroed it in for 100 yrds an loosened an placed the 100 elevation dial marker on the metal indicator tab an tightened up the larger outside nut to keep the position. If I want to shoot to 200 or 300 yards, do I turn the dial to 200 or 300 to have correct allowance?....

I sent you a PM with a link. Download the information, I'll leave the link active a couple days.

Mike


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