pistol rear sight dovetail widths? any one know them?

by cable, Tuesday, June 11, 2013, 23:07 (4187 days ago)

i have an odd pistol, a french 22 lr semiauto called the Unique brand.. these are superbly accurate, but some idiot [ not me ] lost most of the works of the rear sight. it is an odd width dovetail, bigger than 3/8", probably metric. i could probably shim a 3/8" adjustable rear to work, but cant find data on what pistols have which dovetail width, so cant figure out what to order

any help appreciated.

pistol rear sight dovetail widths? any one know them?

by Harry O-1, Wednesday, June 12, 2013, 09:45 (4186 days ago) @ cable

I have a couple of foreign guns with odd dovetail widths. The one that I had to replace was 9mm. That was just shorter than the standard 3/8" so you can either widen the dovetail or shorten the sight, whichever works best for yours.

Difficult to measure with absolute accuracy unless...

by Hoot @, Diversityville, Liberal-sota, Wednesday, June 12, 2013, 13:15 (4186 days ago) @ cable

it's "over pins" (Option 2 below).

Two thoughts...
An inside caliper 'might' get you close enough. This assumes there aren't that many choices and that the choices are further apart than a few thousandths. The edges of the caliper won't get into the corners far enough so the slot will be a skosh wider than the measurement.

If you had a couple of pieces of smooth wire, you could put them into the corners of the dovetail, measure between the wires as accurately as possible, measure the wire diameter, report it and then I'll dust off a couple of long unused brain cells to give you the calculated dovetail width. Gauge pins are best but any smooth, straight, consistant wire should do. We'll have to assume the dovetail angle on this one but I'd bet pretty heavily it's 60 deg.

Difficult to measure with absolute accuracy unless...

by lee jurras @, hagerman,NM, Wednesday, June 12, 2013, 15:03 (4186 days ago) @ Hoot

Most that I've seen on dovetail cutters are 60 degree. Don't recall seeing any different. Measure width of open cut, then measure dovetail cutter as it sits in cut. That's why they make 60 degree files with a safe side, so the last few thousandth can be hand fit and slide in with a brass punch. They also make tools for pressing it in, similar to those made for the Glock, or one can easily fabricate one for general use. :-P

wondering what the width of various replacement sights

by cable, Wednesday, June 12, 2013, 15:28 (4186 days ago) @ lee jurras

are, so i can order an adjustable rear sights [ say one, made for a sig oor smith and wesson ] and then modify that sight to work on this pistol

so really was wondering what is the width of dovetail on various standard auto pistols, so i can order one that is close to what i need.

wondering what the width of various replacement sights

by lee jurras @, hagerman,NM, Wednesday, June 12, 2013, 16:09 (4186 days ago) @ cable

Cable never saw a stardard measurement, most US sights are standard to take a 60 degree dovetail cut. Just use a 4 flute center cut end-mill 3/8" dia. then add your 60 degree dovetail cutter to widen as necessary...then you still might have to use your 60 degree safe side file for final fit. Cut short and finish with file to be safe.
If you don't have that file they are available from Brownell's :-P

The way I understand it, he's looking for measurements

by Paul ⌂, Wednesday, June 12, 2013, 16:15 (4186 days ago) @ lee jurras

on the sights to see which one would come close to fitting the pistol. from there he could then file down the sight or open up the dovetail as need be - or might have to build up the sight with a shim for that matter...

The way I understand it, he's looking for measurements

by lee jurras @, hagerman,NM, Wednesday, June 12, 2013, 18:23 (4186 days ago) @ Paul

PAUL, I understand that , But I don't ever remember any sight mfg giving demensions. Suggest you call Brownell's Tech Service Dept and ask if such a bird exists. FWIW dept. I suggest trial and error if nothing else exists. I'll bet any sight made in the US will or can be made to fit. :-|

It's amazing what can be done with a bit of JB Weld

by Paul ⌂, Wednesday, June 12, 2013, 18:29 (4186 days ago) @ lee jurras

a file and the courage to "go where no man has gone before". :) The old Stevens Favorite lost its front sight way down south of the big river. There was nothing in that country that fit. Everything we found was too small. It ended up cobbled together with a shim to take up the slack. The last I knew it still had that shim and it still works. Looks like a home made mud pie, but shoots well enough.

It's amazing what can be done with a bit of JB Weld

by lee jurras @, hagerman,NM, Wednesday, June 12, 2013, 21:46 (4186 days ago) @ Paul

Probably more home gunsmith jobs finished with JB than most are willing to admit. It covers a multitude of sins. Also does great for "glue ins" in BR stocks. :-D

That, and hand tools

by FOG, Wednesday, June 12, 2013, 22:16 (4186 days ago) @ lee jurras

I don't even have an electric drill, much less a rotary tool, or an actual machine tool.

In fact, the only 'power tool' I have (besides guns − lol) is a 12V Viair-brand air pump for filling my tires, and I only got that because there's hardly any other option these days.

There are no real gas stations anymore, which leaves the Pay-As-You-Go type of pump now found everywhere else.

Unfortunately, the air hoses of most of those are on a pulley connected to a 10-ton winch that only spins in one direction.

I'm sure you can guess which one. :-D

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Given a little more info, I could probably find the answer

by FOG, Wednesday, June 12, 2013, 18:37 (4186 days ago) @ cable
edited by FOG, Wednesday, June 12, 2013, 19:08

'Bigger than 3/8' and 'it might work if shimmed' suggests something less than 1/2" (12.7 mm), but it's not clear by how much.

Meantime, here are a few notes that might be of some help.


1. Measuring The Dovetail

This should not be too difficult, given the right tool.

Assuming the sight is completely gone and the dovetail is 'empty', it should actually be easy using a Pocket Optical Comparator, which is basically a small magnifying glass (think 'loupe') with a reticle having one or more scales embossed upon it.

These can be found at places like Amazon or Edmund Optics for under $100.

I'm pretty sure if you placed the comparator against the side of the empty dovetail, then looked through the backlit dovetail using the loupe, you could measure the dovetail width to at least ±0.1 mm, possibly even more accurately.

If you don't want to spend the money, I have a comparator you could borrow, but it only goes up to 10 mm, and the minimum increments are 0.2 mm. Still, it might work. If you're interested in trying it, let me know. You would pay shipping both ways, of course, preferably Priority Mail ($5.80 x 2 = $11.60; you would not have to insure it).

My comparator also has an inch scale: Range 0.0 - 0.5 inches; Major Divisions = 0.1 inches; Minor Divisions = 'Teeny Tiny'. Of course, you would have to convert to metric, for which I recommend the free program Convert.


2. Dovetail Angle

Some are 65°, even in this country.

OTOH, I'm not sure how much it matters (I have no idea of the tolerances).


3. Misc

3/8" = 9.5 mm

10 mm = 0.394"


4. UNIQUE Parts Source

Bob's Gun Shop "We Bought ALL Remaining Factory Parts!"


5. 'Fitting' The Dovetail

Always file the sight, never the dovetail (except, I suppose, as a 'last resort').

In addition, it should only be necessary to remove material from the BOTTOM of the sight (not the sides).

A normal Mill file can be used (I have used both 6" and 10" files).

It's also usually easiest to keep the file still and move the work across it, alternating directions with each pass.

When properly fitted, you should be able to press the sight into the dovetail approximately half way with your fingers/thumbs. If it still doesn't tap-in the rest of the way easily enough to suit your preferences, you can remove a little more material from the bottom of the sight.

In all cases, GO SLOWLY.


HTH :-)

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Part Deux (lol)

by FOG, Wednesday, June 12, 2013, 19:26 (4186 days ago) @ FOG

6. 'Fixing' The Sight In The Dovetail

Once 'fitted', you may notice small gaps about/around the sight, especially at/near the base.

I'm not sure, but I think this is usually because the angles don't exactly match.

In any case, you can 'fix' this using loctite.

Most suggest 'red' (permanent) to fill the gaps, but I'm not sure it matters; blue might work just as well, particularly on a .22.

Just a few drops around the base, perhaps one at each gap, usually does the trick. Most of the loctite will be wicked into the crevasses. What remains can be wiped off with a rag or cleaning patch (but quickly, or it will also remove the portion you want to stay in place).


HTH² :-D

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Part Trois: Inside The Pocket Optical Comparator

by FOG, Wednesday, June 12, 2013, 19:56 (4186 days ago) @ FOG
edited by FOG, Wednesday, June 12, 2013, 19:59

And outside... :-D

(NOTE: Picture taken at 1X on the camera)
[image]

As you can see, *it's used*.

That means *it can be borrowed and used some more*. :-D


[image]

As you can also see, I keep it in a film canister, so it's more or less ready to ship.

Again, let me know if you want to borrow it (@ cable, just in case).


HTH³ [image]

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Part Deux (lol)

by lee jurras @, hagerman,NM, Wednesday, June 12, 2013, 21:40 (4186 days ago) @ FOG

No disrespect to anyone on this site, but from answers seen I doubt more than a couple members could set their mill to cut the dovetail closer than 5 degrees,
Or even cut 60 degree dovetails with a 60 degree cutter. :-/... Would take some pretty good eyes with slide and sight held up to bright light to discern any objectionable misfit with 65 vs 60 degree cutter.A slight tapping on the edge of the dovetail cut after the sight is fitted would or could remove this gap. Not exactly a tool maker fit, but close enough for gov't work. ;-)

It doesn't appear to matter much to gun & sight makers

by FOG, Wednesday, June 12, 2013, 22:04 (4186 days ago) @ lee jurras

I only know I've seen a lot of mismatch between parts and guns from different makers, most of which I thought was due differences in the angles, because it looked that way every time.

Otherwise, no offense taken here.

The first, last, and only time I ever ran a mill, I took too deep a cut and almost tipped the damn thing over...In a *small* room...SCARY!

Mind you, I had *NO* training, just orders to 'design a part and build it from scratch in the machine shop'.

You can bet they never asked me to do *that* again. :-D

The good news is, my design was a complete success − in the right hands.

Well, that and no one got killed. ;-)

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It doesn't appear to matter much to gun & sight makers

by lee jurras @, hagerman,NM, Wednesday, June 12, 2013, 22:34 (4186 days ago) @ FOG

I've seen Rembrandts with a lathe and mill, makes me feel sometimes like a kid with crayons. My Bridgeport was quite capable of working in tenths, took me a while to be able to, even with it. That's when a surface grinder is handy, but you better have a light touch. A blown grinding wheel can be very discerting. :-P

I learned a few things about machining by designing parts

by FOG, Wednesday, June 12, 2013, 22:49 (4186 days ago) @ lee jurras

And, to some extent, systems of parts, mostly scientific apparatus.

Then later, I learned a little bit more by working directly with some very talented machinists.

Suffice to say, Lesson Learned: 'Stay out of the shop!!!' :-D

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A few 'misfits' I've seen

by FOG, Wednesday, June 12, 2013, 23:33 (4186 days ago) @ FOG

1) 3/8-inch Blanks

Marbles and another brand I don't recall in:
• Winchester 94 Wrangler (ca. 1980)
• Marlin 1894 .44 Magnum (pre-safety)

From this small experience, I learned to order (at least) two of them: One blank 'always' fits better than the other(s).

I also tried fitting some front sight or other to the Winchester, but that one didn't work out due to interference with the barrel band. I relieved it to fit, but didn't like the resulting cosmetic appearance and so re-installed the original.

2) Glock Sights

I changed the sights on five of them:
• G26 (x 3)
• G34 (x 2)

Suffice to say they appeared to vary a lot. Certainly enough to see the 'cracks', especially with a little magnification and good light (like a task lamp).

Those are just the most recent.

In the past, I've seen the 'problem' on factory guns, plus I've seen it on custom jobs (which is one reason I've done it myself a few times).

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A few 'misfits' I've seen

by lee jurras @, hagerman,NM, Thursday, June 13, 2013, 00:01 (4186 days ago) @ FOG

Quality this day in age is custom only, then some of those leave things to be desired. I feel most mfg's feel that if the owner wants a better fit he'll do it himself. Hell the average Bear would not know quality or precision workmanship if it jumped up and bit him, guns other otherwise. :-D

Thanks to all. i do have a dovetail file from brownells...

by cable, Thursday, June 13, 2013, 14:51 (4185 days ago) @ lee jurras

and couldnt find it. but yesterday i did. i think with this and my friend JB Weld, i can rig something up.

i must say, i am again impressed with the knowledge all of you have. i never even knew what an optical comparator really was. i wouldnt attempt to do any work on a lathe, i know my limits.

when it comes to things like spinal injections, tissue biopsies, joint work, etc. i am exceeding skillful, for some reason. but mechanically otherwise, i dont dare try to do most stuff.

thanks again to all!

I find the optical comparator *VERY* useful

by FOG, Thursday, June 13, 2013, 18:17 (4185 days ago) @ cable

And at today's prices, downright cheap.

An example in the Utility Dept: Identifying 1.2-mm and 1.3-mm screws for eyeglasses. Plus others literally too numerous to mention.

On prices, I've had mine about 25 years or so, and I'm pretty sure I paid somewhat more for mine (something like $150). Which is an example of high-tech 'winning' yet again, I suppose.

Certain tools are very important to me, and a Pocket Optical Comparator is one I definitely recommend having.

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well, looks like Bobs has the sight blade, screw, and spring

by cable, Thursday, June 13, 2013, 14:55 (4185 days ago) @ FOG

and i do have the rest of it. maybe i wont have to use JBWeld after all.

thanks so much!

Excellent!

by FOG, Thursday, June 13, 2013, 16:50 (4185 days ago) @ cable

:-)

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