This is a discussion on M14 Iron Sight Guide within the Reference forums, part of the M14 M1A Forum category; Greetings,
My Father is a retired Marine and is writing his Viet Nam Era Memoirs and has a technical question regarding the M-14 sights adjustments.
I count sixty-four clicks from full bottom to 1100 meters using a USGI standard M14 rear sight on a 1980s SA, Inc. M1A receiver. The elevation setting for 100 meters is eight clicks from bottom on this rifle and typically is that as well on a USGI M14.
I found this old thread whilst searching for info re targeting my M-14S/305 (18.5"). I've just finished replacing the factory rear sight with one from a USGI M-1 Garand. I've not been out to the range to sight in the new rear sight yet. I was at 19 clicks with my 100 yd zero because my front sight is very tall, or so it appears on my 18.5" barrel).
See how the top of the sight is above the level of its 'protective' ears. I'd like to get the blade and the aperture down out of the stratosphere, so I'm following the directions given by Fulton Armory on shortening the front sight.
But I must be measuring the height of my blade differently because it's not in the ballpark with the heights shown in your comprehensive post. Using the Fulton method of measuring from the top of the blade to the flat between its base and the protecting 'ears', I'm getting just ~0.440", yet you're showing the 'std' (22") M-14 height as .562" and the 'std tall' as ~.720".
According to my calculations, in order to end up with my 100 yd zero at ~7 clicks, I ought to be trimming ~0.10" from my existing front blade.
That would give me a height of ~0.340" and put the top of the sight just below its ears. Are my ears that much shorter than standard? Why does my sight look different that those posted on here? IDK-- Maybe the whole 'disproportionate' thing is an optical illusion. The numbers seem to make sense.
IDK if I'm measuring incorrectly or what, but I'd like to be certain I'm on the same page as you before I go filing and shooting, and making myself all crazy.
BTW-- My sight is ~0.080 wide (same as the std for 22") so I'll likely be needing something like a tall NM 0.062 on my 18.5" barrel ...(?)
Thanks for your very illuminating series of posts. If you or any other members can help me out here I'd be most appreciative.
Very thorough report. I would like to add/amend to the rear aperture discussion.
Aperture diameter is not just personal preference. The smaller your aperture, the greater the depth of field will be, and the more sharply you will see the front sight, especially if you have limited vision. The only watchout is that as the aperture gets smaller, it lets in less light, and so on very dim days, exceptionally small apertures might provide too dim a sight picture.
ShootingSight LLC makes modified non-adjustable apertures, with steel inserts in USGI apertures to create 0.042", 0.0465", 0.052", and 0.0595" non-adjustable apertures. They also make NM hoods and hooded assemblies with the 1/2MOA adjustment in 0.0465" diameter.
ShootingSight also makes kits for rebuilding hoods that contain detent balls, belleville washers, c-clips, and an installation tool for the c-clip.
The correct lens insert for an M1 or M14 to offset your focus from infinity (which is where the uncorrected human eye will relax, or where eye doctors adjust the corrected eye to), is +0.50 diopters. This power will move your relaxed focal point to the hyperfocal distance of the front sight, so you can see the front sight and the target, with both in focus simultaneously.
Art: Thx for that tip. Can you provide me with this +0.50 diopter insert for my (USGI) M-1 Garand aperture, or is it necessary to have a 'match' sight to begin with? If so, do you happen to know if it's possible to order just the hooded 'aperture' (ie c/w rack) or do I have to get the entire assembly? I just got done installing the complete M-1 sight.
ps-- Went to eyedoc for complete exam (A-OK) and described my shooting/acuity requirements. Ordered shooting glasses: Right eye mild correction for 20/20 (hyperfocus?) Left eye-- transition from distance to reading. Should be in tomorrow. Stay tuned to this frequency...
(I don't want a scope/red dot on my M-14)
Usually if you want to use a lens insert, it is a small 3/8 diameter lens that is inserted inside the hood, so that solution won't work for a regular aperture.
I do sell just hoods, but there is no way to attach a hood to an existing aperture because there is some precision machining to be done to the rack. You would need to replace the entire rack/hood assembly, and even then you'd be limited, as the standard NM hood is too big in diameter, so it bumps into the sight base when you drop your elevation, so you lose several clicks on the bottom end of the travel - I think this issue was covered in the OP's thread.
That said, I make hoods that screw into an AR flip sight that are smaller in diameter. These have screw-in interchangeable apertures. So a project I am thinking about undertaking is to drill/tap a USGI rack to accept one of my hoods. The thought is that with a smaller hood, it might fit in a GI sight base without bumping. You would lose the 1/2MOA adjustability, but you could get reduced apertures.
This would not be Garand match legal, but it would be SR legal.
As to your doc's correction for your eyes, based on the front sight distance and the lens equations, the difference between your distance vision and your shooting prescription should be +0.5 in the sphere value of your prescription. Once you are shooting, you can tell if the lens is right, as a higher (more positive) sphere value will improve the front sight at the expense of the target, and a lower (or more negative) value will improve the target at the expense of the front sight. Your goal is to be able to see both with similar clarity at the same time.
The "M-79" shown in your pics-- That's from a grenade launcher, eh?
Yes it is.
The dovetail is the same size as for the M14/M1A platform.
It is primarily an option for the Socom rifles with the factory gas lock/muzzle brake.
Where it really shines is with a Aimpoint Micro on an Ultimak M-8.
The higher thinner blade works great for cowitnessing.
and centers the dot better.
M79 front sight, Socom large rear aperture with rifle in this configuration.
Last edited by geepee3; December 12th, 2013 at 06:05 PM.