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I am installing a Lyman reveiver sight on a Marlin model 30 AS. Two questions: 1) am I correct that to remove the factory rear sight I should drift it FROM left to the right relative to looking down the barrel from butt to barrel? 2) The factory front sight is 3/8-inch high bead mounted directly in a barrel dovetail slot (no barrel ramp). If I measure from the rear of the current fron sight to the front of the new receiver bar the distrnace is 21 1/2 inches. Is there some formula that will tell me if the existing front sight will zero at 100 yards or is it necessary to do a trial and error shooting session?

Thank you
 

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Left to right is the way to go. Yes, there is a formula, but I will admit to being math-challenged and have never had much luck with it. I will say, though, that odds are good you will need a higher front sight. With all my leverguns, I have just obtained front sight blanks, installed them, and filed them to the height and shape I want. I like a silver blade front sight, and blanks are available cheap from Dixie Gunworks.

http://www.dixiegunworks.com/product_info.php?products_id=7456
 

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FWIW, Brad the distance between the front/rear has nothing to do with zeroing the rifle - It has to do with calculating sight heights with a formula, IIRC.

Correct sight height(s) do, however.

In my somewhat limited experience of working on rifles (45years), most leverguns with front sights mounted directly in the barrel (no ramp) will rewadily zero @ 100 yds, unless a higher-than-normal, top-mount receiver peep is used, and/or hanloaded ammunition ballistics exceed the sight parameters.

IOW, you should be good to go with the existing front sight height - don't forget to fill the rear barrel dovetail with a slot filler blank, either purchased or made from the forward part of an old longleaf rear sight.

There is what's called a Sight Height Calculator available online, which allows a shooter to determine how much different a height front sight is needed then the current sight by measuring the vertical distance of groups from zero @ 100yds and the peep sight in the mid-height position.
The amount "off", in inches, is plugged into the formula to result in how much more/less front sight height is needed to achieve zero.

Or, you can simply measure your rifle, as illustrated here: http://www.brownells.com/UserDocs/Miscellaneous/004-07inst.pdf

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The Hog Whisperer (Administrator)
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Put the receiver sight on before you remove the rear sight. If the gun was already sighted in, then adjust receiver sight till you see the usual sight picture in it. Then remove rear sight. Easy!

If it won't line up (as the top-mount receiver sights are prone to), then you'll need a taller front sight. I'm not exactly sure how to accurately measure that beforehand, except to try and figure out how much taller the bottom position of the top-mount receiver sight is over the existing line of sight. Maybe carefully hold a yardstick along the sight plane and see where it meets the new sight?

All I've ever used are side-mount Williams, Lyman, and one old Redfield and they go low enough that it hasn't been a problem, that I recall.
 
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