For my second Ruger 10/22 project, I decided to take a challenge I had given up on when working on my first one. The challenge: find a notched, adjustable rear sight that fits in the Ruger rear dovetail, and a hooded front sight to go with it.
I learned a lot from putting my first rifle together, and put that to use in messing around with this one. Even so, there were a few hitches.
A major problem with firearm parts/accessories is that sellers don’t give you the numbers you need.
For adjustable rear sights, information on height through the range of adjustment isn’t available online. I had to pester customer service. In one case, patient souls that they are, they came up with the numbers and got the sale — but the dovetail turned out to be the wrong size. So I sent it back. I found another adjustable rear sight that looked like it would fit the Ruger dovetail, possibly a nicer one though also made by Italian firm LPA, and they didn’t give the adjustment range, either. I emailed their customer service and never heard back. Guess what, they probably lost a sale due to poor information on their website and non-existent service.
For the front sights, the ‘height’ of the sights was available online. The problem was, they didn’t say how they measured the height. There’s at least two ways you can measure the height of a front sight, and finding out how they measure their sights kept me from ordering the wrong one. This time, thank you customer service.
A similar problem is probably happening a dozen places in the US, this very moment. A lot of people who sell muzzle brakes/recoil compensators don’t give the height or diameter of their product. Without that, how are you supposed to know if you’ll be able to sight over the top of it? You can do one of two things: buy the unit and hope it’s not too big, or pester customer service. If you’re buying through Amazon, they can’t help you, because it’s not their product.
I also have two quibbles. My newest two Rugers are ‘modern’ versions and the news isn’t entirely good.
The plastic barrel bands bend easily under torque. They’re held on by a nut and a screw, and the nut and screw fit so loosely together that they actually rattle — like they’re two different sizes. Also, the bottoms of the factory front sights are not flush with the dovetail cut. They tilt forward, and you can see daylight in between. This happened because Ruger added a little ‘bump’ of metal underneath and towards the back, where the sight meets the face of the dovetail lug. This helps tighten the fit between the sight and the gun, but they could have gotten the same result by simply machining the parts to closer tolerances. Oh, and some of the dovetails, though theoretically all the same, are cut tighter or deeper than others. Things like this raise concerns about what else Ruger might have done that’s less than precise.
On the plus side, the extended bolt release is an excellent addition to the overall design, so I’m getting one to retrofit my first Ruger.
Enough of that. Below you’ll see the measurements and calculations I used for choosing the parts I needed. If you find that’s boring and you just want to buy what I got and install the parts, you can skip it over. If you’d like to do something similar to what I did, you can use my measurements and methods, and work from there.
Calculations for front/rear sight combo
Note: Both Ruger dovetail cuts measure 0.375″ x 60 degrees. Measurements are in inches. Everything here is measured and calculated from the center of the bore, because that’s what the sights have to line up with.
Rear sight mounting point measurement/calculation
Diameter of barrel behind rear sight: 1.00 (where the bottom of the new sight touches)
Center of bore to outside of barrel behind sight: 0.500 (one-half the barrel diameter)
Rear adjustable sight height calculation
Note: This is the distance from the bore to the top of the new sight at different elevations, which sets a range for the height of the sight you want to get for the front.
Bottom of barrel to top of rear leaf, lowest setting: 1.28 (basically, barrel diameter plus 0.28)
Bottom of barrel to top of rear leaf, highest setting: 1.40 (basically, barrel diameter plus 0.40)
Bore to top of rear leaf, lowest setting: 0.78 (half of the barrel diameter plus 0.28)
Bore to top of rear leaf, highest setting: 0.90 (half of the barrel diameter plus 0.40)
Thus, the front sight needs to be between 0.78 and 0.90 tall.
Front sight mounting point measurement
Note: The ‘height’ measurement of the globe sight starts at the widest part of the dovetail where the flat bottom would meet the bottom of the dovetail that’s cut into the dovetail lug, and you measure upwards from there to the center of the globe.
Diameter of barrel band (the band that holds the front sight): 0.622
Bottom of barrel band to bottom of front dovetail cut (measured with front sight removed): 0.600
Depth of dovetail cut below diameter of barrel band: 0.022 (0.622 minus 0.600)
Bore to outside of barrel band (1/2 diameter of barrel band): 0.311
Bore to bottom of dovetail cut: 0.289 (0.311 minus 0.022)
Lyman globe front sight calculation
Note: Take the distance from the bore to the bottom of the dovetail cut. Add the heights of the different available sights, which are measured from bottom of the dovetail cut to the center of the globe. Pick the front sight where the total measurement is between 0.78 and 0.90 from the bore, which is the range of the adjustable rear sight when it’s installed.
0.289 + 0.404 = 0.693
0.289 + 0.494 = 0.783
0.289 + 0.584 = 0.873 <====this one 
0.289 + 0.854 = 1.143
Calculation of max possible diameter of muzzle brake/recoil compensator
Note: Here, just find the distance from the bore to the bottom of the globe portion of the sight, then multiply that by 2.
Bore to center of Lyman .494 sight 0.783
Diameter of globe portion of sight 0.600
1/2 diameter of globe portion 0.300
Bore to bottom of globe portion 0.483 (0.783 – 0.300)
Max possible brake/comp diameter 0.966 (2 x 0.483)
That’s it for the numbers. Looks amazing, but I had to cheat. I totally gave up trying to get information on adjustable rear sights before ordering the right one. It proved to be impossible. So I ordered the Millett, hoping for the best, and I got lucky. The dovetail is a good, snug fit. On top of that, there are two ‘grub’ screws that lock the sight into place. After installing the sight, I was able to measure the adjustment range and take things from there. And that part only worked because Lyman gives real measurements.
So now you know what parts to get if you want a hooded front blade/rear notched leaf set of sights using the existing dovetails, but without all the pain. How’s that for a time-saver?
Now comes the fun part. To install the new sights, you have to take out the old ones. When you go searching around the ‘net for advice on how to remove them, you’ll read plenty about people bashing their rifles with huge steel objects to get the sights to move.
It’s really not that hard. First off, the Ruger dovetail cut is tapered. If you whack the sight on the wrong side, you’ll just wedge it in tighter.
With the muzzle pointing away from you, the sights come out the right side. The hammering is done on the left side. There’s also a rule of thumb, which works in all sorts of pounding situations: use the lightest hammer that will do the job. What I use is a small punch, and a tack hammer, on my wooden work bench. Some serious taps and a few lighter ones, and the sights come right out.
If you want to attach a muzzle adapter , the Lyman sight can’t go in just as it is. You have to cut off the left and right sides so that the dovetail is as narrow as the dovetail mounting lug, and you can find out how to do that in a brief article I have filed under Miscellanea. I’m pretty happy with the muzzle brake I added, which has design features found on brakes costing twice as much or more.  It measures o.982 in diameter, which is a bit more than the maximum allowance, but that doesn’t interfere with shooting. There is a ‘top’ and ‘bottom’ to the muzzle brake, so it will have to be ‘clocked’, or rotated into the correct vertical/horizontal position. Once there, you want to hold it in position, and this can be done with an inexpensive jam nut. 
Because the barrel band on the new Ruger is plastic and basically worthless, I replaced it with a solid aluminum band which incidentally has two Picatinny rails. 
With a bit of extra money to spend, I gave into temptation and bought a set of Lee Shaver reticles (‘inserts’) for the Lyman front sight.  The cross-hairs are fun, but eventually I settled on the extra-fine front post. My wife (who has her own 10/22) went for the cross-hairs with the center circle. A good part of the fun of a globe sight is the possibilities with reticles, so it was a good buy.
1. Magnum Research, Millett adjustable rear sight for Desert Eagle, white outlined, #DEP302/W, http://www.magnumresearch.com/Sights/Magnum-Research-Millet-Adjustable-Rear-Sight-White-Outlined.asp
2. Track of the Wolf, Globe Front Sight, medium .584″ height, 3/8″ dovetail, with eight inserts, http://www.trackofthewolf.com/Categories/PartDetail.aspx/875/1/FS-17-AUG
3. Tacticool22, Ruger 10/22 Threaded Barrel End – 1/2-28 TPI – Stainless, http://www.tacticool22.com/shop/ruger-1022-threaded-barrel-end-1228-tpi-stainless-p-51.html
4. Amazon.com, AR-15 .223 1/2×28 Competition Short Muzzle Device Brake, http://www.amazon.com/AR-15-Competition-Short-Muzzle-Device/dp/B009O0KIV8/ref=sr_1_13?s=sporting-goods&ie=UTF8&qid=1362626178&sr=1-13
5. CNC Warrior, 22289 1/2-28 Jam Nut, http://www.cncwarrior.com/ProductDetails.asp?ProductCode=22289
6. Amazon.com, ProMag Ruger 10/22 Carbine Tactical Barrel Band, Black, http://www.amazon.com/ProMag-Ruger-Carbine-Tactical-Barrel/dp/B003BAAJVG
7. Brownells, Lee Shaver – Globe Sight Inserts, Post & Aperture Card, 17A Sight, http://www.brownells.com/rifle-parts/sights/sight-parts/sight-inserts/globe-sight-inserts-prod12372.aspx
Here is a view of the Millet adjustable rear sight, from the side. You’ll notice that there is a gap between the leaf (portion that has the sighting notch) and the barrel. The leaf has been elevated to the position where the sights are zeroed. In combination with the Lyman front sight, this has the rear sight near (but not at) the top of its adjustment range.
Here is a 3/4 view of the Millet adjustable rear sight. All in all, it looks fairly stock to someone who wouldn’t know better. I’ve found I dislike the white outline, and will shortly paint it flat black.
Here’s the muzzle brake, jam nut, globe sight and muzzle adapter when everything is put together. The muzzle brake has two ports on the top, to help reduce muzzle rise. To make sure it stays on the top, you need a jam nut to keep it from unscrewing during use. The jam nut is essentially circular, with two flat spots which you can grab with a 3/4 inch wrench. The globe sight is the same as the one on my first Ruger project, except it’s not as tall. That’s because of the height of the Millet adjustable sight. The muzzle adapter is held on with a set screw that goes up from the bottom. It has an Allen head, and is tastefully recessed.
This is what things look like with the ProMag barrel band. It doesn’t look entirely stock, but it doesn’t really stand out that much, either. It’s made of a single piece of aluminum and clamped on with an Allen-head screw. The only reason it’s there is because the barrel bands on the new Rugers are plain crap. They’re plastic and aren’t tight enough to stay on unless torqued down so hard that the plastic bends. At the time of this writing, all other styles of aftermarket barrel bands were sold out, because apparently this was a very popular problem.