Ruger MKII rear sight dovetail

Tony S45 · Post by **Tony S45** » Tue Jan 11, 2011 10:58 am

I bought a MKII fixed sight pencil rec/barrel that (thankfully) shoots accurately but a few inches low of POA/POI at 25yds. I prefer a 6 o'clock hold at 25yds.

The fixed dovetail looks quite similar to the adjustable sight dovetail on my adjustable MKIIs and 22/45s but I don't have a micrometer to measure it.

Therefore, I want to install an adjustable Ruger rear sight on the pencil barrel which should easily get me to the POA/POI that I want. Before I get out the hammer and brass punch and start wacking away on this pristine fixed rec/barrel to free the fixed sight, can some one please confirm that the dovetails are the same, or not.

stork · Post by **stork** » Tue Jan 11, 2011 11:51 am

tony,
For a temporary fix, take a flat file to the front sight. That will raise your point of impact. If this is going to be a rough service/knock around piece you may want to try that.

Just remember, it doesn't take much to make a BIG BIG difference in the point of impact. One or two strokes at a time.

Depending on your final choice of rear sights you will probably have to replace the front sight with a taller one. None of my MKII's have fixed sights, but if I remember they sit very low on the receiver compared to the adjustable versions.

Georgezilla · Post by **Georgezilla** » Tue Jan 11, 2011 2:45 pm

Tony, the dovetails on the MKII fixed sight and the MKII adjustable sights are indeed the same cut.

As Stork noted, you will probably need to replace the front sight for a taller one. The fixed MK rear sight is very low when compared to the adjustable and the front sights have the same height respectively.

Tony S45 · Post by **Tony S45** » Tue Jan 11, 2011 4:14 pm

Thanks for the replies.

Forgot to mention that I must give it a wack to adjust windage over approx an inch at 25yds as well.

Yes, I could sloooooowly file down the front sight while checking to POI every few swipes but I'm the stubborn type and would prefer the adjustable rear, if possible.

You are both correct: both the front and rear fixed sights are quite low. Will drift out the fixed rear sight; drift in an adj rear; lower the rear sight all the way down and cross my fingers on the way to the range.

Again, POA/POI = a few inches too low at 25yds. (my prefered 6 o'clock = approx 3" above POA at 25yds.) which should allow the rear some room to go upwards because that's a total of 5"+ of elevation change. Will post the results when I can get 'er done and get back to the range.

Post by **Bullseye** » Tue Jan 11, 2011 7:29 pm

To have a good range of adjustment on your standard sights you'll need an LPA (low profile adjustable) rear sight. This sight will use your existing front sight. Otherwise you will need a much taller front sight blade to use the regular Ruger target adjustable rear sight. Midway or Brownells carries this sight for the Ruger.

R,
Bullseye

Tony S45 · Post by **Tony S45** » Tue Jan 11, 2011 8:17 pm

Roger, Bullseye.

Had an LPA on a CZ75B that I foolishly sold a few years ago. Excellent quality sights. The LPAs for the Rugers are on back order and cost $60+.

The bottom of the fixed sight blade is approx 1/8 lower than the lowest bottom of the adj sight with the dovetails equal. As stated above POI needs to come up approx 5"+. Is 1/8" way too much for a 6" barrel to lift POI up 5"? I don't have a copy of the sighting equation.

(I also have a couple of extra adj sight blades. One could be filed lower by approx 1/16th" and still fit correctly into the sight body.)

Post by **Bullseye** » Tue Jan 11, 2011 9:18 pm

Here's a version of the sight height calculator on the Brownell's website http://www.brownells.com/.aspx/lid=1309 ... Calculator About mid-way down the page is the formula if you want to compute it manually. Remember to use the same measurements (Inches, Feet, Yards, etc.) across the formula to keep your calculations correct. Inches are the standard unit for this formula to get the corrective measurements in thousandths of an inch.

Remember the sight base on the rear adjustable target version is significantly higher than the fixed rear sight on the receiver, this is why the low profile sight is required with the factory front sight blade. Otherwise when you place the adjustable base on your pistol the problem will no longer be slightly low, it will be impacts too high and there will be no way to bring them down without using a significantly taller front sight blade - like an Orca's dorsal fin.

R,
Bullseye

Tony S45 · Post by **Tony S45** » Tue Jan 11, 2011 9:43 pm

Thanks, Bullseye.

The equation indicates a net change for 5" of elevation to be 0.047" adjustment while installing the rear adj sight will increase it approx 0.125" and then it will require the front Orca fin.

Looks like Stork's idea is the best option. Use a flat file: take a couple of swipes; shoot a few rounds until I get the POI up to the center of the bullseye.

Many thanks for all the replies.

Post by **Bullseye** » Tue Jan 11, 2011 9:51 pm

Also keep in mind Tony that different brands of ammo will result in changes in POI. If you're truly only one or two inches low at 25 yards then try some other ammo or hold a little closer to the black with your front sight.

R,
Bullseye

Tony S45 · Post by **Tony S45** » Wed Jan 12, 2011 2:03 pm

Roger, Bullseye.

Using CCI SV the pencil barrel from a bench groups tighter and about an inch lower and just slightly to the right of Fed bulk groups. That's quite typical for SV I believe.

I'm much to obsessive compulsive to try to use "Kentucky windage" which nevers works well for me. Drives me crazy. Prefer to work out the details of a problem until I'm satified that I have done all that I am capable of doing -- which sometimes isn't much!

ruger22 · Post by **ruger22** » Fri Jan 28, 2011 2:18 pm

In the reverse idea, would it work to put a standard model fixed rear sight on a Mark III bull barrel? I understand the dovetail is the same, and the front sight would probably need considerable shortening?

Post by **Bullseye** » Fri Jan 28, 2011 5:26 pm

I've never considered doing that, but mechanically, the fixed rear sight will fit in the dovetail slot.

R,
Bullseye

Tony S45 · Post by **Tony S45** » Tue Feb 01, 2011 8:11 pm

Took your advise , stork, and used a flat file and very carefully and slowly filed down the front sight while shooting a group between each filing. Now have the gun at 6 o'clock hold at 25yds. using CCI SV. Will smooth the front sight top and paint it with flat black.

Thanks for everyone's comments.

ruger22 · Post by **ruger22** » Wed Feb 02, 2011 1:43 pm

Instead of flat black paint I recommend Birchwood-Casey Super Blue. Works perfect for holster wear on my Ruger front sights. About eight bucks a bottle, goes a long way. Just dab it on with a cotton swab, wait a minute, and wipe off. Not real durable, but looks like new.

Tony S45 · Post by **Tony S45** » Thu Feb 03, 2011 6:21 am

Thanks, ruger22. I'll check it out.