How do you mesure a dovetail ?????

[abunaitoo]

I have a Brno .22 rifle I want to install a Anschultz peep sight on it.
The dovetail is larger than the one on the sight.
I'm not sure what the dovetail on the sight is.
How do you measure the size of a dovetail??????

[M-Tecs]

http://webmachinist.net/dovetailcalculating.html

http://www.machinist-calculator.com/Dovetails-Eng.html

http://neme-s.org/Model_Engineer_Files/Gauging%20Dovetail%20Slides.pdf

http://www.texas-mac.com/Browning_and_Winchester_BPCR_Dovetails.html

http://www.brownells.com/gunsmith-tools-supplies/measuring-tools/dovetail-slot-measuring-gauges/dovetail-measuring-tool-prod14.aspx

[abunaitoo]

UGGGGG!!!!!
OK. Dodn't think it was so involved.
Close as I can measure, sight dovetail is 11mm, rifle dovetail is 13mm.

[BrentD]

Get some soft lead and tap it into the dovetail then knock it out (left to right) and measure.

[abunaitoo]

Sorry. Forgot to say it's the rear sight.
Filler will not work.

[BrentD]

Why not? I have done this many time for a rear sight. I don't know what a Brno is however.

[dale2242]

I have had the darndest time trying to catch flighty things to measure their tails.
Sorry, I couldn`t help it....dale

[Bad Water Bill]

I have had the darndest time trying to catch flighty things to measure their tails.
Sorry, I couldn`t help it....dale

Try using a LARGE musky net.:bigsmyl2:

[MBTcustom]

It's trigonometry. You measure the dove tails the same way you measure threads, with wires.
However, just like with threads, in practice if you want a perfect line for line fit you have to use the thing you intend to put in there to measure it. IE: when you can tap it in place with a drift punch and it stays put, that's perfect.

[KCSO]

To get a rough idea you can make a tool to do this... you file a dovetailed section into a lengthwise taper. Then you just slide it in till it's tight and measure where it stops in the dovetailed section of the barrel. I usually just reach in the drawer and grab out a handful of dovetail cutters and fit and try.

[Minerat]

I have Brno Mod 1 22lr too, but my rear sight is a leaf design like dangerous game rifles have. My Grandfather bought it in 1950 while in Peru building a dam, for what was then a whopping $10.00 US.

I have a Win Mod 94 30-30 that the front and rear sight dove tails are so loose that you can not sight the gun in because the sights move with every shot. So I have been thing about installing new sights on it so your questions was timely. I found this on Brownells but a little pricey but might work.

http://www.brownells.com/gunsmith-tools-supplies/measuring-tools/dovetail-slot-measuring-gauges/dovetail-measuring-tool-prod14.aspx

[Catshooter]

Minerat,

I have solved the loose dovetails by installing a small set screw in the sight.


Cat

[KCSO]

On curing loose dovetails... First of all most dovetails are nominal, the cutters are used way too long and the signts are squeezed in with a press sometimes so tight they bckle a thin barrel. (taurus 45 colt rifles are a prime offender). In light of this most of your 3/8 dovetail sights are some oversize and need to be fitted by filing off the base. (Please work on the cheap part first) NOw if your dovetail is just a little loose and the barrel is thick enough under the dovetail, take a sharp center punch and set up a few divots in the bottom of the dovetial in the barrel. This raises the bottom and lets the sight fit tight again. This is the same idea as the set screw but doesnt require a tap that most folks don't have. A more rounded center punch is used on the top of the barrel to lock the sight in place after the gun is sighted. Foreign guns may have a larger than standard dovetil and you will need to get special sights from Brownells. This will be your only solution if you get a dovetail that was hogged out too much unless you have a tig welder and are willig to recut and refinsh.

[Minerat]

Catshooter,

I'll have to look into that. May have more questions once I have time to look at the gun again. Can I bug you at that time for more details?

[Hardcast416taylor]

Minerat,

I have solved the loose dovetails by installing a small set screw in the sight.


Cat

Another way to fix a loose sight in a dovetail slot is to turn the sight upside down and using a pointed center punch make 4 or 5 indents on the sight bottom then re-install.Robert

[BrentD]

Punching divots into a sight base is one thing, but punching divots into the barrel - NO. NOT ON MY RIFLE.

You can do a whole bunch of things to fix a dovetail issue. If it is not a lot and you don't have a safed 3-corner file or don't want to use it, you can put a shim under the sight and tap it into place. Beer cans make good shims. The aluminum will smush to fit. Blue Loctite is your friend.

You can also sweat on a shim on the front or back of the male dovetail if the difference is large. Adapting a 3/8" dovetail to an original Sharps Rifle dovetail works well this way.

You could also find another sight if need be.

But NEVER use a punch on the rifle barrel directed at the bore of the rifle. NOT ON MY RIFLE!

Just food for thought.

Brent

[BrentD]

Punching divots into a sight base is one thing, but punching divots into the barrel - NO. NOT ON MY RIFLE.

You can do a whole bunch of things to fix a dovetail issue. If it is not a lot and you don't have a safed 3-corner file or don't want to use it, you can put a shim under the sight and tap it into place. Beer cans make good shims. The aluminum will smush to fit. Blue Loctite is your friend.

You can also sweat on a shim on the front or back of the male dovetail if the difference is large. Adapting a 3/8" dovetail to an original Sharps Rifle dovetail works well this way.

You could also find another sight if need be.

But NEVER use a punch on the rifle barrel directed at the bore of the rifle. NOT ON MY RIFLE!

Just food for thought.

Brent

[Catshooter]

Minerat,

Sure. When I fit a new sight to a rifle I tend to file them a bit loose and use a set screw for securing it. I dislike beating on a rifle much.


Cat

[cajun shooter]

You should never use a punch on the dovetail cut on the rifle. You always use the punch on the bottom of the sight about three or four times. The rear sight can be purchased for about $30 but not so for the rifle barrel. Later David

[.45Cole]

Can you call Anschultz and ask them what the dovetail is cut to?