I have a Springfield M1A Loaded model rifle and I replaced the rear sight aperture with a National Match "hooded" aperture. I was able to sight this rifle in at 25/200 yards but it required that the rear sight be "cranked all the way down" to the lowest level.
I have thought that maybe I need to grind off some of the teeth from the bottom of the rear sight aperture so that will might be able to move lower in the sight base but I am not sure that this will solve my problem.
Does anyone have any comments or suggestions as to what the problem might be before I take the rear sight apart and have to re-zero my sights again especially if this does not solve the problem?
Thank you for any assistance that you can provide.
Terry
First, not sure I see the problem...if it's got a good zero, great.
I wouldn't fool with the rear assy. If you must have some space under the rear sight, do it by putting a taller front sight on the rifle. This will have the effect of lowering the point of impact, and requiring more clicks up on the rear to hit the same zero.
BTW, the opposite modification is more common. If you are shooting iron sights out at 1000 yards, it comes to something like 40 clicks....makes the cheek weld durned difficult. The fix is to cut the front sight down...
HTH!
Actually, the rear sight base that is used for the hooded aperture IS cut lower to make room for the aperture.
It was designed to be used with the NM sight base, which is 1/2 MOA per click, and a fine thread (64 TPI) windage knob.
It CAN be used with the normal base, but will not go as low as needed, unless modified...
You CAN grind the base of the hooded aperture at an angle past the first tooth, and it will give you some ability to lower the elevation.
Also, if you grind the base of the aperture, you can also change it out without disassembly...
Just crank it out, and crank the regular one back in. Of couse, the regular aperture must be modified also...
When the aperature is all the way down does the hood contact the base? Or does it bottom out/stop with a gap between the hood and the base?
Some folks disassemble the rear sight, remove the aperatue and grind off a portion of the bottom of the aperature. Sometimes the tip of the bottom will contact the receiver and stop the aperature from moving downwards further. I know I've seen pictures of what the aperature looks like after folks do this but so far I haven't found one. Do a search on the web and you many find such a picture along with the description of how to do it.
My M1 NM rear aperature is completely bottomed out to allow me to hit point of aim at 25 meters. I didn't see any need to be able to adjust it lower if it hits where I want it to hit.
If you are on at 25/200 you'll be about 1 3/4" to 2" high at 100. No real need to lower the rear sight any further if you know that.
I assume you are using 6 0'clock hold.
If you have M1a loaded, it already has a NM rear sight base. Which means windage adjustments are 1/2 MOA and elevation is 1 MOA. When you install the hooded aperture you gain your 1/2 MOA adjustments by turning the hood 180 degrees. If the notch on the hood is pointing down, this will give another 1/2moa drop in POI if needed.
If the hood is already bottomed out you probably wont gain much by grinding any teeth off the aperture. You can grind that bottom tooth to a taper, and make sure you remove any burrs the teeth may have, but I would read about it first.
Other than that a taller front sight is the best fix.
A couple of books I would recommend are; The M14 Owner's Guide by Scott A. Duff and John M. Miller, and The M14 Assembly Guide by Walt Kuleck and Clint McKee.
Also www.m14tfl.com This a great resource and has alot of valuable info.
D-fly
http://appleseedinfo.org/smf/index.php?topic=6004.msg55660#msg55660
http://fulton-armory.com/%5Cfaqs%5CM14-FAQs%5CNMRearSight.htm
wcmartin1, Thank you. This is EXACTLY what I was looking for
Thank you to all my fellow Appleseeders that responded.
Terry