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Old 12-07-2009, 08:47 AM
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Charlotte
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The rear iris issue has not been addressed by anyone other than Larsen Biathlon and perhaps Altius who have adjustable irises for the Izhmash. The 9.5X1m thread size is a custom size and seems very unlikely to find a tap to open the existing threads from 9.0 to 9.5 unless you have it custom made and at that point you might as well buy another rear sight. The centra economy rear sight is under $200 and has 9.5X1m thread size for the iris.
Although this makes those with machinist backgrounds reel and gnash their teeth the 18mm plastic inserts are oversized by 1mm which means that you only have to remove half that much in a swipe around the circumference with a nail file. Once the insert is placed in the front globe the edge of the outer perimeter is not visible (by a margin of about a tenth of an inch) and the clamp does not allow the insert to move so, all anguishing aside, any minor variation from perfection won't show up on your target. I know. I've proved it. Anything else is unfounded speculation.
Certainly if you were to sit and sand flat spot after flat spot you'd have a nasty looking and grossly undersized insert but by rotating the insert on its edge across the nail file and checking for fit with each revolution it only takes a few rotations to get it to fit.
BTW, the plastic inserts are the bomb! Great sight picture, just make sure you block the top of the globe off with tape to keep light from reaching the edge of the plastic insert.

Last edited by Charlotte; 12-07-2009 at 08:49 AM.
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