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Old 11-21-2019, 11:16 AM
Mike in Wis. Mike in Wis. is offline
 
Join Date: Oct 2009
Location: Wisconsin
Posts: 339
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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. :-)
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