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Adjustable rear sight
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Paul1262 View Drop Down
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    Posted: Jul 20 2018 at 1:33pm
My rear sight is marked I.R Co. (International Register Co.) with no numbers on the side. The adjustable slide markings are 100 - 200 -250 and 300 yards. Today at the range, I had to have the sight positioned on the 300 yard mark to achieve reasonable groups at 100 yards. Does anyone know what the correct front post height should be in order to correspond to the slide markings? Thanks.
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Freedom View Drop Down
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Points: 31 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Freedom Quote  Post ReplyReply Direct Link To This Post Posted: Jul 30 2018 at 9:07am
My Inland sight likes to be set for 250yds to hit 100yd bullseye. Seams like that is not unusual with rebuild carbines.
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Paul1262 View Drop Down
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Freedom,

Thanks for sharing your experience. I believe that using the 250 yard adjustable sight marking for a 100 yard target is just about right to compensate for a front sight blade that is too tall. My front sight blade measures .313.
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Donnie View Drop Down
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Originally posted by Paul1262 Paul1262 wrote:


Freedom,

Thanks for sharing your experience. I believe that using the 250 yard adjustable sight marking for a 100 yard target is just about right to compensate for a front sight blade that is too tall. My front sight blade measures .313.

I have not searched, but what length is 'normal'? I just measured mine and, depending on how I take the measurement, mine measures .275".


Just getting into this carbine thing, I have only shot at the 50yd distance. I don't think my old eyes will serve me well at 100yds.
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The correct height for an unfiled front sight is .785" minimum from the top of the blade to the centerline of the bore per Ordnance specifications. The specification says "The dimension shown include sufficient stock to adjust height of blade in assembly and after targeting."
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Donnie View Drop Down
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Originally posted by jackp1028 jackp1028 wrote:

The correct height for an unfiled front sight is .785" minimum from the top of the blade to the centerline of the bore per Ordnance specifications. The specification says "The dimension shown include sufficient stock to adjust height of blade in assembly and after targeting."

After reading your post I tried to measure the front sight as advised. Mine is approximately .740"...and I do mean approximately. I am not sure how to get an accurate reading on that measurement.
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jackp1028 View Drop Down
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Points: 1276 		Post Options Post Options   Thanks (0) Thanks(0)   Quote jackp1028 Quote  Post ReplyReply Direct Link To This Post Posted: Jul 30 2018 at 5:56pm
Donnie, I know that dimension is hard to measure, but that's how it's noted on the Ordnance drawing. If you have a typical thin wall Type 1 sight it should be close to 1.115" (Correction Typo, was 1.155" s/b 1.115") measuring from the top of the blade to the bottom of the sight with a caliper. Type 2 will be a little more (~.015") because the wall is thicker. All bets are off for the Type 3 cast sight.
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blackfish View Drop Down
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Filed or unfiled, too high or too low, perhaps buying a USED sight, you need to know blade height relative to bore axis.



Measure both GREEN and RED dimenions with a caliper to 0.001", not a tape measure.

The blade height above the bore axis (where the lines cross) is simply GREEN-(RED/2)

Valid for any Type front sight (not just "Type 2")
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What if you measure the bore, then measure from the top of bore to top of sight and add the 1/2 of the bore measurement?
M1's are FUN!!!
TSMG's are more FUN!!!
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Points: 151 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Paul1262 Quote  Post ReplyReply Direct Link To This Post Posted: Jul 31 2018 at 12:04pm
Thanks for the photo, it really helps to see a picture of what is being discussed. My type 2 front sight measures .796" from the center of the bore to the top of the blade. You mentioned that Ordinance specification called for at least .785". I assume that .796" would be within their tolerance guidelines.
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Donnie View Drop Down
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Points: 336 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Donnie Quote  Post ReplyReply Direct Link To This Post Posted: Jul 31 2018 at 2:22pm
Blackfish, as with the saying a picture is worth a thousand words, your photo makes it explicitly clear. Thank you, sir.
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