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AR-7 Front and Rear Sight Modifications

Discussion about the AR-7 and all of it's versions before and since Henry
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BMCTED
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AR-7 Front and Rear Sight Modifications

Post by BMCTED » Fri Dec 09, 2022 8:21 pm

As I wrote in the "AR-7 Complaints" post, I would like to write some articles that will deal with some of the problems that the AR-7 rifle family has. I had posted the below material on another web forum some time ago, but it is long gone. I have revised it, but don't be surprised if you recognize some of it. Some of this material is my own invention. Much of it comes from 50 years of shooting, reading gun magazines and books or carefully listening to guys who know far more than I ever will about firearms. I humbly recognize their input. I hope some may find this useful.

This should address number 13 Sights hard to use, and at least partially address number 14 Rifle is inaccurate on the Complaints about AR7 rifles post. https://henryrifleforums.com/viewtopic.php?f=68&t=14215


AR-7 Front and Rear Sight Modifications

Before getting started on modifications, perhaps it would be a good idea to learn a little about how aperture sights work, how to sight in or zero a rifle’s sights and maybe get a couple of terms straight. Years ago it was very easy to get information about working with a rifle’s iron sights because that’s what was on all rifles when you bought them. Now it seems like everything has scopes and red dots and nobody knows how to work with aperture sights.

Frankly, I don’t like either scopes or red dots, mostly because every time I pick up a flashlight … the damned batteries are dead. Iron sights don’t fog up, the reticles don’t loosen over time and get all turned around, they don’t lose zero every time you move the rifle … what’s more, iron sights just don’t have batteries. Also, iron sights are just as accurate as scopes; I can show a LOT of videos of young guys making shots 700, 800 even 1,000 yards using iron sights. When I went to basic training back in 1970, we shot targets out to 500 yards to qualify … using iron sights, something I think I could still do today … if the government was willing to pay for the ammo. It should be noted that the US military used rear mounted aperture sights and front post/blade sights on all of their rifles from the M1903 Springfield to the M-16. The accuracy of those rifles, as well as the marksmanship skills of those behind them is/was very highly regarded.

All of this aside, aperture sights are what is found on all AR-7 rifles, so we’re kind of stuck.

If you already know all this stuff below and couldn’t possibly learn any more, just scroll down to the GOAL section.

For the rest of us, instead of me typing a bunch of stuff you won’t want to read anyway, I found the best videos I could find to explain some things. They are all well put together and easy to understand.

HOW TO SIGHT IN OR ZERO A RIFLE’S SIGHTS

As a guy who restores military rifles as a hobby, there are a number of things I do to a firearm before I consider it OK to go shooting with. All of these things have become a habit and ones that I even apply to brand new firearms. I NEVER accept that a manufacturer has sighted in my firearm correctly, or assume that what they did is going to fit me. I ALWAYS zero in my firearms before they go “on-line”.

“Sighting-in” or “Zeroing” is a process of adjusting the rifle’s front and rear sights to make a fired bullet hit a target, a target being the place/thing you aimed at. As I learned in the Army, everybody should zero in their own firearm simply because everybody’s head and eyes are shaped differently, everybody’s cheek weld is different and everybody holds a rifle differently. What fits me just may not fit you.

I don’t bother with a formal (i.e., store bought) “target” when sighting in. I take a clean sheet of 8X11 paper or a white paper plate, and put a 1 ½” X 1 ½” piece of duct tape in the center of it for a target. I fire 5 shot groups. I always start zeroing at 25 yards.

Moving on to the how-to Vids: The first vid is pretty good. “How to Sight a 0.22 Rifle at 25 Yards”. Ignore anything having to do with “clicks” and concentrate when the narrator talks about moving “groups” and not single shots or flyers. https://www.youtube.com/watch?v=edXjFRxhr3k&t=93s

The next vid teaches something I learned a long time ago, F.O.R.S. or Front, opposite, Rear, same. Memorize it. If you end up owning more rifles, knowing it will help a lot. Good information, simply given. “How To Adjust Iron Sights”: https://www.youtube.com/watch?v=HnoQeNhXRGE


HOW APERTURE SIGHTS WORK

It’s all about proper sight picture and alignment … and available light. A far better discussion about sights than I could ever give can be found at a YouTube vid called: “Discover timeless peep and Patridge post sights~Accurate, fast, and deadly at any range!” which can be found here: https://www.youtube.com/watch?v=MC59CH_f9Xo&t=1537s

At 46 minutes it’s a bit long, but it’s everything you should know if you are going to use aperture sights. Make up a bowl of popcorn.

All main battle rifles used by the American military, throughout the last century, from the M1917 Enfield to the M-16, were fitted with rear mounted peep sights and a front blade or post sight. The US Military insisted on aperture rear sights/post or blade front sites because they are fast to the target, extremely accurate, durable, hold zero well and easy to teach. They are not necessarily cheap. I currently own one of each of the US battle rifles issued in the last century, except for the M1903 Springfield and the M1941 Johnson and love the sights found on all of them.

After you watched this vid, you must be asking yourself, “So why the heck did Gene Stoner and the Armalite boys put target apertures (i.e., holes) on what is essentially a field gun and not a target rifle and why the heck has everybody who has built them since done the same thing?”

BONUS VIDEO

Since this has turned into a multi-media presentation, here’s a Bonus Vid. Despite the accent, Robski is a sniper in the US Army and a pretty fair shooter. BTW, the ladder at the rear of the ’03 Springfield is holding 2 sights, a peep sight and a notch sight. They both can be seen clearly @3.58 in the vid. Watch Robski as he goes to work: “Clapping Targets with American Classic M1903 Irons at 700yds”. Yep, iron sights work just fine. https://www.youtube.com/watch?v=SD_wpIN7-_k&t=2s

TERMS

The word “aperture” means “hole”. A “peep-hole” is a small hole through which to … peep. In the context of rifle sights, an “aperture sight” and a “peep sight” are exactly the same thing: a hole through which one looks to aim a rifle. These sights should be as close to the shooter’s eye as possible.

Although I can find nothing official, “Target Aperture sights” have a hole the inner diameter of which can range from about .003” to .035” and can be used on distant targets. Target Apertures require a lot of time to aim and a LOT of light. Gunblue490 explained why and how they are used.

A “ghost ring sight” is an aperture or peep sight constructed as a thin ring with a hole in the center. It is designed such that when a shooter looks through the hole at the front post and target … the ring disappears. This helps the shooter ignore the ghost ring and fully concentrate on the front sight post and target. Ghost ring sights have a hole the inner diameter of which can range from about 0.093” (3/32”) to 0.203” (13/64”). They are generally used on closer targets, are much faster to aim and work in dim light very well.

A “front sight post” and a “front side blade” are exactly the same when viewed from the rear of a rifle. They are different when viewed from the side, but that has no impact on aiming a rifle.

SOME GOOD INFORMATION:

The Charter Arms AR-7 front sight is aluminum and it’s blade is .0825” wide.
The Henry AR-7 front sight is plastic and it’s blade is .073” wide.

The Charter Arms front sight fits tighter in both CA and HRA front sight bases on their barrels than does the HRA sight.

Both the Charter Arms and the Henry have rear aperture sights made of stamped steel. They are interchangeable. Please note that this steel is VERY hard.

The Charter Arms rear sight has one hole of .125” in diameter.
The Henry rear sight has two holes, one of .075” diameter, the other is .0465” diameter.

GOAL: To modify the front and rear sights on the AR-7 rifle to make them more user friendly, and maybe a little more accurate.

REASONS FOR: These modifications are relatively simple to do, are low cost, and provide a good benefit to the shooter, especially one with diminishing eyesight.

REASONS AGAINST:
Cost of the rear sight of an AR-7 from Henry Rifle is $2.50. Cost of the front sight of AR-7 from Henry rifle is $2.75. Plus shipping and handling. Please adjust for inflation.

TOOLS REQUIRED: Although a younger person with better eyes and steadier hands might be able to do these modifications with a hand drill, a drill press might be necessary for some of these modifications. Also needed are some drill bits and a threading tap. A Dremel tool and a couple cut off discs would be helpful. Other tools and materials required will be mentioned in the text.

FRONT SIGHT

Sights and sight adjustments are measured in minutes of angle (MOA). 1 MOA is equal to 1'' at 100 yards, or 1/2" at 50 yards, or 1/4" at 25 yards. Therefore, that 1 ½” square of duct tape I mentioned earlier, when viewed at 25 yards away is 6 MOA. If your front sight appears as wide as that square when viewed from 25 yards away … it is a 6 MOA sight.

(For the record, 1 Moa is REALLY 1.047" @100 yards. 1 Moa is .26175" @25 yards. But Heck, it’s an AR-7, right?)

Some experts say that a “target” front sight should be about 5 MOA wide, and a general purpose or field sight should be about 6-7 MOA. A battle sight is 8 MOA. Other experts say a front sight having a width of .072” is all you need. There is a bunch of math out there to help you figure this all out.

So what? As a practical matter … What the heck does all that even mean? How does the “expert” know if you can even SEE a 6 MOA wide front sight?

Save the trouble, skip the math and tell the experts to go to lunch. The AR-7 isn’t a target rifle and the front sight has to be comfortable for you to use.

In case this come up on Jeopardy or some other trivia contest, the front sight post on the M16A2 measures .070”. The AK47 and the SKS are about .072”.

If you think a thinner sight might help you cut a finer shot, go ahead and file yours down maybe .005 off each side until you get it where you want it. If you mess it up, new front sights are $2.75 each from Henry.

Hold Down Screw Mod, Witness Marks and Fluorescent Orange Paint.

Since the AR-7 is a “survival rifle”, it seems to me that the front sight should be protected in some way from getting moved around. You would have thought that Gene and the Armalite Boys would have come up with something. Anyway, some of the front sights on the AR-7 are so loose, they move on their own or with just a gentle touch of a finger. To protect the front sight, I thought of installing a removable sight hood, as can be found on the Mauser K98, but it’s too large and will not fit in the stock. I thought of adding a couple of “wings” but couldn’t come up with a way to easily attach them. So I settled for a simple allen head set screw to hold the sight in place.

PROCEDURE:

I am working with the aluminum front sight from the Charter Arms AR-7, but this will work just as well with the plastic front sights on the HRA version. Remove the front sight blade from the rifle. Making sure not to cut through the tallest part of the sight blade, with the Dremel tool and cut off discs, or other appropriate saw and files, cut a 5/32” gap from the top to the bottom of the sight blade. At the center of this gap, drill a 9/64” hole completely through the base of the sight. Using an 8-32 Tap, thread the hole completely through. Insert an 8-32 X 1/4" allen head set-screw. To lock the sight into place when the sight is installed on the rifle, simply tighten the allen set-screw.

I ground down the remaining rear portion of the rear sight blade leaving about 1/8”+/-. I painted the back of what remains of the front portion of the blade with some fluorescent orange paint.

Now when I look through the rear sight of my AR-7 I see a bright orange sight post having a nice flat top.

To create witness marks to be used as a reference after you have zeroed your rifle, I used a silver Sharpie marker and covered the rear part of the base of the sight with silver. I also put a bit of silver in a corresponding location on the top of the of the sight base on the barrel. Once I adjusted the windage of my AR-7, I scratch a straight line (the “witness mark”) on the two patches of silver, so I can return the sight to its zeroed position should it ever get knocked out of place. If you need to re-zero your AR-7 for any reason, almost any solvent will remove the silver so you can re-apply it and make new witness marks.

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FWIW: I see that front sights for the AR-7 can be bought in a molded in a very bright day-glow orange. I think these sights fairly scream “HERE I AM!” and are somewhat inappropriate on a “survival rifle”, but to each their own.


REAR SIGHT MODIFICATIONS

After viewing GunBlue490’s video, I hope that AR-7 shooters reading this have become convinced that, if not a Ghost Ring, at least a larger aperture in the rear sight of their rifle would be useful in terms of speed in acquiring their target, truly a benefit in low light situations and extremely helpful for those whose eyesight might be diminished. But what size aperture should it be?

A large number of hunters agree that .096” is about the best inside diameter for a ghost ring sight. They indicate accuracy and light transmission the reason for this choice. For the record, the larger aperture sight on the M16A2 rifle from back in 1970 measures about 3/16” or 5mm, which is a REALLY BIG HOLE! Without getting in the weeds, from what I remember, this sight is good out to about 300 yards. The other aperture on the M16A2 measures about 1/16” or 2mm and is good from 300 yards on out. I have the same Williams sights on my Ruger 10/22 that Gunblue490 has on his. The ghost ring on that rear sight measures 13/64”, another fairly large hole.

.096” falls in the middle of the 3/32 – 7/64 drill bits most of us have. Considering low light situations, I chose to drill a 1/8” aperture. You can go larger or smaller as you like.

Remember I mentioned earlier:

“Both the Charter Arms and the Henry have rear aperture sights made of stamped steel. They are interchangeable."

The difference is:

The Charter Arms rear sight has one hole of .125” in diameter.
The Henry rear sight has two holes, one of .075” diameter, the other is .0465” diameter.”

I own both a CA AND a Henry rear sight. This means, if I drill a 1/8” hole in my Charter Arms rear sight, giving it 2 holes, I will have two sights having 1 large aperture for general purposes, and 3 smaller Target Apertures, should I want them.

You would think this is the simplest modification you’ll ever do, but the devil is in the details. Because I was drilling a new hole in the CA rear sight, I had to very carefully locate my center punch not only left and right, but also locate it the same distance from the center of the sight blade as the hole on the opposite side. This was necessary so that the elevation and windage adjustment of the front sight would remain constant and not require re-zeroing every time I changed rear sights.

If you are modifying a Henry rear sight, just go ahead and drill through one of the existing holes. That hole will center the drill bit as you go. If you would like a set of sights with 4 apertures like I have, buy a rear sight from Henry Arms, drill the largest hole on one of them to 1/8” (or whatever) and drill the smaller hole to 1/16”.

As above, I used a silver Sharpie marker to create a silver spot on the sight blades to scratch in a witness mark. You should zero and put a witness mark on ALL of the apertures, that way you would be able to change apertures in the field should lighting conditions permit. I find it useful to zero my sights out to 100 yards and put on a smaller witness mark, so I can adjust my sight to deal with different distances, 25 yards and 100 yards. On the receiver, about ¾” from the top of the rear sight hood, using a modeler’s saw, I cut a datum line on the right side of the rear of the receiver for a more permanent mark.

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Just to show how intricate aperture sights can be I've included this last bit of trivia. On the left is the modified Charter Arms rear sight. The one in the middle is an unmodified Henry rear sight. The one on the right is a Parker Hale target sight mounted with a Parker Hale eyepiece having 6 apertures on a rotating disc. The apertures range in size from .03 to .08.

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Last edited by BMCTED on Sat Dec 24, 2022 12:16 pm, edited 4 times in total.
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BMCTED
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Posts: 94
Joined: Tue Sep 07, 2021 12:35 am
Location: central NoGa.
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Re: AR-7 Front and Rear Sight Modifications Now with Photos

Post by BMCTED » Thu Dec 15, 2022 5:44 pm

I was looking at older posts on this website and found a post from North Country Gal on Wed., 12 June 2019 with some very good suggestions for using aperture or peep sights. The information is very good, so I copied and pasted it here. Her explanation on aperture size demonstrates exactly why having a selection of 4 aperture holes for an AR7 survival rifle is a good idea.


Some basic points on using a peep sight may help.

- Do not attempt to center the front sight in the hole in the peep sight. Just look though the peep, forget it, and concentrate 100% on the front sight. Your eye automatically seeks the brightest point of light coming though the hole in the peep and that is the center. The idea of a peep sight is to take the rear sight out of the sight picture. Consciously trying to center the front sight in the peep aperture (hole) defeats the purpose.

-Aperture size (hole size) needed changes with lighting conditions. A peep can sharpen up your sight picture IF the hole size is small enough for given lighting conditions, but going too small, as in reducing visibility of the front sight, will result in poor accuracy. Most competition shooters use an adjustable aperture to fine tune aperture size for given lighting conditions and target visibility. Going with an aperture opening that is larger than needed for light conditions will not give you the maximum potential accuracy the peep is capable of producing, but it is better than going too small and it is certainly good enough for field work, plus being more comfy to use. For woods hunting, especially, most hunters go with an overly large aperture size for the sake of proper sight visibility and quick sight acquisition. In other words, better too large than too small when it comes to aperture size.

I find that the .096" Skinner aperture size is a good all around aperture to use for shooting under a wide variety of conditions. Usually takes a bright sunny day for me to get away with using the .40". Back in our deep dark woods, there are days when going with the .125" size or even going ghost is a must to be able to use a peep sight.
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