The Ding Dong Ya Say! ( I like the sound of Ding Dong, don’t you?)
In comes this nice new Ruger® American Rifle in .308 equipped with scope mounts. Well, actually it came in with a client. My client says he wants peep sights on it. “OK,” says I. “This will cost, seeing that there is no provision for iron sights. I will probably have to do some modifying to parts and possibly, but not likely, to the rifle. Why do you want peep sights instead of the scope it is ready for?” He allowed that since it is such a short rifle, it would make a good brush gun, and he wants peep sights.
OK! So when it comes time to schedule in the Ruger®, I start checking online through the Brownells catalog, and then the MidwayUSA catalog, then the Williams Gunsight catalog and the Marble Arms catalog. When that failed, I called both Williams and Marble. Guess what? The Ruger American is too new with too few requests for either of them to spend the time developing iron sights for it. Sort of like the reason AGI hasn’t made an Armorer Course for the new Chang Tzu 4mm Micro Assault Rifle. So now what?
After explaining the situation to my client and reaffirming that, yes, I can still equip his rifle with peep sights, he says “Do it.”
The first step is to do some measuring to find the height of the various parts of the rifle above the centerline. In this case, one half of the diameter of the muzzle, .594” is .297.” Always measure to the nearest thousandth of an inch to keep from getting confused. At the breech end of the gun, start by checking the tolerance between the bolt and receiver. On the American, it is very tight. Measure the bolt diameter, .855”, then the bolt channel in the receiver. On the Ruger®, the slope of the rear of the channel makes it difficult to get a precise measurement, but the fit of the bolt, while smooth, is very tight, so I just used its diameter.
One half of the bolt channel diameter (bolt in this case) is .428”, plus the thickness of the top of the receiver, .250”, gives the height above center, .678.” Making an assumption (I do not have the measurements of the rear sight yet.), that the lowest aperture setting would be .250” above the receiver, that means that the front sight bead needs to be mounted at least .928” above the centerline at the muzzle. This would allow an error factor that could be compensated by the rear sight adjustment. Does that make sense?
Having ascertained those parameters, what can I do to fit this gun with sights? With that in mind, I needed to do the math that would put the front and rear sights in proper relationship. Here is an opportunity for the real gun gurus like Bob, Ken, Jack and Darryl, plus both Genes, to make the necessary corrections.
I will admit that I am a neophyte in gun design. I am a tinkerer by heart, and I repair, customize, modify, etc. guns. The custom rifles I have built were all equipped with scopes. It is easy to replace iron sights, drill and tap a rifle for scopes, bore sight and zero a rifle and so on, but this was going backward from scope to iron sights.
Another factor is that I did not want to drill new holes, if possible, nor did I want to cut any slots. “Any metal removed cannot be replaced” is one of my mottos. My favorite one is from Albert Einstein: “Everything should be made as simple as possible, but not simpler.” I can complicate almost anything, at times. Any metal removed may also weaken the overall structure.
Personally, I would like to have tang mounted peeps that are relatively close to the eye, but they are not really suited for modern rifles with tang mounted safeties. What features are on this gun that can be exploited? The scope mount holes. Period.
What rear sight with peeps can make use of those holes? The Williams “WGRS” Receiver Sights had the wrong hole spacing. On the other hand, the Marble Arms® #30 Universal Rear Sights, with a front hole and a rear slot, and available with large and small apertures, partially filled the bill. Problem: these sights are designed to be mounted in front of the receiver on the barrel, where there is a healthy slope. The slope on the American is not gradual as with a full size rifle; but it is only a slight problem. Isn’t it? Sure. Incidentally, the bottom contour radius matched the top of the receiver perfectly, although the peep aperture was considerably higher than .250.”
Now, about the front sight, who has sights that might work? The Marble sight ramps were not tall enough. The Williams Gun Sight company had a taller ramp, the 3/8th (.375) inch Shorty Ramp that was also compact for smaller rifles. It being a narrow ramp, it also required a sight blade with a narrow base (?), and the lowest blade available was .312” high, making the total height .669.” The way I saw it, that ought to line up a convergence pretty well with the Marble sight set at its lowest position. I still did not have the sights or know the Marble measurements, yet.
The Williams Shorty Base has a hole in the dovetail and can be mounted by screw or silver soldered into position. Several years ago, I decided to quit using silver solder and resort to an adhesive that I used while managing several product lines in a manufacturing company. I have had much success with it in tactical shotgun conversions. Loctite’s Black Max, which I used up at about a quart a day, is a shock resistant cyanoacrylate, toughened with elastomers, high strength industrial adhesive available from Brownells in .10 oz. tubes (#297-380-040WB). When using Black Max, all surfaces must be stripped of any impurities. Bluing does not have to be removed. A little goes a long way.
First, locating the position of the front sight ramp is made a little easier by setting up a system of alignment. I used the scope base screws partially in place at the most extreme holes to reduce error in establishing the position of the ramp with the blade already inserted. Positioning is merely a matter of lining up the bead with the scope base screws. Trace the outline of the forward portion of the ramp with the front of the ramp about 1/4” to 3/8” from the muzzle, or whatever looks good to you, as it is not critical. You need the outline to facilitate positioning the ramp once you have applied the adhesive. A small bead of Black Max at each side edge will suffice.
Place the ramp, with the blade, in position and hold it in place using that mightiest of clamps, the rubber band; making sure that the front bead still aligns with the scope base screws. No great pressure is needed, but work precisely and quickly at this point, as the adhesive will get ahead of you if you do not. If you do have a problem with a smear, fret not as good old acetone on a Q-Tip will clean it up easily, as will ethyl rubbing alcohol. Small bottles are available at most pharmacies.
Well, mounting the rear sight is relatively simple, no? Just putting it on, yes. What kind of sight picture do we have? The front of the Marble base, not being mounted on the slope of the barrel, obscures the lower 1/3rd of the peep picture. So out comes the grinder to form a notch in the front to open the view for the peep, as shown.
It is now time to see what happens on a target. At the 25 yard indoor range, the bore sight laser is nowhere to be found, unless you look at the ceiling. So I installed a .450” blade, the tallest narrow blade for the ramp, on the front sight. Now the laser was on the wall near the ceiling. If sight is as high as you can get, obviously the rear sight has to be lowered. I do not have a milling machine, but I thought that it would be a not too difficult a job to use the Mk I Calibrated Eyeball, a Dremel Grinder and crocus cloth taped to the receiver to carve out the bottom channel and maintain the needed contour to fit the receiver. I thought that removing about .250” should do it. Between the grinding mentioned and a sanding flapper wheel which had an identical radius, it only took about an hour.
Back at the range, the laser was, at least, shining lower on the wall about a foot above the target. Another .250” should do it, but I was not going to spend my time grinding and sanding. I took it to my trusted machine shop and had them remove the final amount. CAUTION: This is the max that can be removed. The hole and slot must have at least .005” metal remaining, more is better, for the screw heads to engage for mounting the Marble base to the receiver. Check your thickness.
Back to the range. AHA! The laser is on the paper, and it looks like it is near the bullseye. Truth be known, I am only a year into this septuagenarian gig. With shooting glasses, the rear sight is a blur, the front sight is a blur and the target is a blur. That is why I normally use a scope. With my reading glasses, I can see both sights and only the target is a blur. So, what the heck, I fired four rounds with the sights firmly (?) in the middle of what I thought was the target. That wasn’t too bad on the grouping for my blurred sight, four rounds in a three inch group – six inches high!? At least it’s on paper, right? Yeah, but it’s NOT on TARGET!! Now what? In retrospect, I should have chosen the wide blade, at .500” high and trimmed it to fit the ramp.
So, here is the rest of the story, as Paul Harvey would say. Rechecking my math from the beginning showed that when I was calculating front sight blade height, I forgot to add the distance from the bore centerline to the top of the barrel . . . major oops!
This is the Williams WGRS 500 Sight Blade designed to be inserted in a barrel slot. As you can see, it is twice the width of the ramp. Fortunately, the dovetail dimensions are compatible with the ramp, so the only work to be done is to bring the width down to match the ramp, as seen here. I used a Dremel cutoff disk to narrow it to a dimension just larger than needed, then, with the blade on the ramp, final trimming was done with a sanding disk.
My Daddy always told me that “you can always cut ‘em shorter, but you can’t cut ‘em longer.” Could I have used the belt sander to get it precise? Yes. Figure a good way to hold it, and go for it. For me, the best grip for the blade was the ramp, itself.
The sanding disk gives a nice polish to the base of the blade, and it gives a nice polish to the side of the ramp, also. If you tried to blue the nicely polished surfaces next to the original surfaces, the refraction index would not match up the new with the old. The answer is to use a Dremel fluffy Buffer wheel that conforms to contours, and give the complete side of the blade and the ramp a nice semi-gloss or matte finish. I did that to the rear sight base also for the sake of continuity.
That done, five or six complete applications of Brownells 44/40 Bluing Crème to both sights that have been heated several hundred degrees with a heat gun brings a beautiful deep blue-black finish. I use a pair of long hemostats to hold some parts during both the heating and the bluing. And yes, the Black Max held up to the heat and bluing techniques as well.
How does it shoot? You have to remember my eyesight. The laser seemed to be converging on where I thought the sights said it ought to be. Four rounds were in the black, so I am happy; I hope my client is. To my knowledge, he is the only person in the world with a brand new Ruger American center-fire rifle with iron sights. Williams and Marble may catch up with me; time will tell.
There is a bonus in this installation. In the pictures, you will notice that the rear scope mount base is in place with no interference to the peep sight. This allows mounting any of the many Red Dot Sights with single point attach-ments that are on the market. Having done all that, here is a tip! “Everything should be made as simple as possible, but not simpler.”
I, at last, made contact with our illustrious GCA Tech Editor-in-Chief Jack Landis, who is a master wordsmith himself, who, very tactfully, mentioned that, not in these exact words mind you, “Well, duh, Clint, you should have talked to me.” Honest, he did NOT say that.
He pointed out, first that the subject had been gone over in an early GCA GunTech, and also that Brownells has a Sight Height Calculator that, having found it, works really neat. (Go sit in the corner with this DUNCE cap, please, and I hadn’t yet owned up to the front height mistake.)
You find it by going to the Brownells Home Page, at the bottom of which, under Site Navigation is an item called Learn. Clicking on that takes you to another page, at the left of which is Sight Height Calculator. Clicking on that gives you this calculator.
Neat, Huh? No dunce corner for you, because it asks for measurements and calculates for you.