Tightening a Dovetail

[michaeldarnold]

I can't seem to find a good method to tighten up the front dovetail on an old Winchester 190 .22 barrel. The old blade sight was broken off and sat too low to be useful so I replaced it with a good sight off a donor barrel.

Any tips/tricks to tighten up the dovetail in that barrel would be fantastic. Shy of just whalloping the steel, which I don't really want to do, I'm stuck, and my blade isn't.

Thanks!

Mike

[dakota.potts]

Shim it maybe?

[g.willikers]

One tried and true way is to dimple the floor of the dovetail cut with a punch.
It raises material to help tighten the sight.

[Pahoo]

One tried and true way is to dimple the floor of the dovetail cut with a punch.

This works and also check the ears to make sure you are back to being flush with the barrel. Just make sure you use a small brass-head hammer/mallet. I once saw the floor of a dovetail that had chisel marks. Center punch is better. Remove sight, left to right and reinstall right to left. .....

Be Safe !!!

[mete]

Shim under the sight

Dimple bottom of dovetail

Tap top of dovetail

Use blue Loctite

Whichever works !

[Hunter Customs]

Here's a method that will work.
1. Place sight in dovetailed centered with the bore or as close to center as possible.
2. Scribe a mark as close to center of the blade as possible on top of barrel.
3. Remove sight and with a flat punch centered on the scribed line displace the edge of the dovetail downward.
4. Now install sight, it should be a snug fit if not do 3 again.
5. Last step is to use a center punch to stake the four junctions of the blade and dovetail.
Done correctly that sight will never move, I always did the four junction stake on all hard use 1911's with a transverse dovetail front sight, never had one shoot loose.

Best Regards
Bob Hunter

[michaeldarnold]

Thanks to all for the quick follow up.

I will be making measurements to find the centerline of the bore to line that blade sight up with.

Bob, your instructions are far more precise than me just smacking the flanges of the dovetail. I believe that with this info, my blade sight will not move until I say it's time to move.


Thanks!
Mike

[Bill DeShivs]

The only reason that a dovetail becomes loose, is that the flanges get deformed upwards.

The logical solution is to simply bend them down again. This is best done gingerly with a brass hammer or punch.

Punching the sight base and dovetail floor only bends the flanges further.

[michaeldarnold]

The issue I have with punching the floor of the dovetail is that by raising the floor, you push the blade sight away from the barrel itself. It does make more sense to move the flanges of the dovetail back down toward the floor, but I also like the idea of locking the sight at the corners.

Mike

[Hunter Customs]

It does make more sense to move the flanges of the dovetail back down toward the floor, but I also like the idea of locking the sight at the corners.

Mike,

Displacing the metal on the edge of the dovetail downward will move the flange toward the dovetail floor.

Do both flanges the way I described in 3, both the front and rear flange directly opposing each other under where the sight blade will sit.

Also if you use a punch as close to the width of the sight blade as possible the displaced metal will not show.

All you need the displaced metal to do is hold the sight in place until you can stake it with the four junction stake method.

Place the staking punch along side of the sight blade, centered on the edge of the sight base and the edge of the dovetail flange, the staking dimples further seats the sight down on the floor of the dovetail making for a nice tight fit.

My first two staking dimples will be left front/right rear or right front/
left rear, whichever way suits you best.

Good luck in your endeavors.

Best Regards
Bob Hunter

[michaeldarnold]

OK! I see what you are saying now by using a wide punch it will effectively V the floor of the dovetail and pull the flanges toward each other and down, making the slot tighter. DUH, I couldn't see that in my head at first and was picturing using a smaller pin punch to dimple the floor, thusly raising material toward the existing location of the flanges.

Thanks

[4V50 Gary]

Shim.

Dimple the bottom of the sight, not the dovetail.

[Unclenick]

I think Michael is arguing he does not want the sight any taller, but I have to ask just how big this gap is? It's hard to imagine it being loose enough to matter whether the sight was in contact with the floor or shimmed up off of it.

If you shim it up off the floor, that's where Loctite can do you some good. But if the dovetail is genuinely stretched loose, then the information you got to gently hammer it back into place is good.

Are you sure are dealing with two sights intended for the exact same dovetail size originally?

[michaeldarnold]

Unclenick,

The sight blade in question is from the original barrel that shipped with the gun. However the magazine retention tube for the old barrel was damaged beyond use and can not be floated out. The barrel had been beaten up and poorman smithed so badly that I was forced to replace the barrel with another. So, in a sense, yes, same sight, same dovetail, same tolerances.

I believe that bringing the flanges of the dovetail down towards the floor will sufficiently tighten and correct my issue. The gap is not visible to the bare eye, but big enough that the blade will slip around in the dovetail. We're talking thousandths of an inch, it really is minor smithing. Locktite may be an answer, but in the long run, it's just a glue...

[Unclenick]

It is an adhesive, but the red permanent type takes a blowtorch to remove. But I think the one you want in Loctite 660 Quick Metal. It's for anchoring bearing races in recesses that have become loose. It fills bigger gaps than the others. You do want to clean the metal of grease before using it, though. I used it to sleeve an oversize lower band for a Garand of mine, and despite being repeatedly subjected to pretty good barrel heat, it never let go.

Glues have come a long way since horsehide and wheat paste. A friend of mine worked helicopter maintenance in Vietnam and told me the skins on the rotary wings were glued on with a special Boeing adhesive. Ever since then, I've considered that the right glue for a job is not to be dismissed out of hand.

[michaeldarnold]

I agree that adhesives have evolved considerably. I may combine that with a mechanical method and never look back.

I need some of that Boeing glue, maybe I'll call in a favor from one of my friends that works there. I am in the St. Louis Suburbs...

[Hunter Customs]

It is an adhesive, but the red permanent type takes a blowtorch to remove.

Or a good soaking for several days in ATF and a heat gun on high heat.

I always used the red when installing compensators on the barrels of the raceguns I built.

I had to change a shot out barrel on a racegun I built for a client, I like to never got that compensator loose. Soaked it submerged in ATF for a week, then applied high heat from the heat gun, it finally broke loose.

Best Regards
Bob Hunter

[mete]

The Huey rotors were completely assembled with adhesive , No welding ,nuts or bolts !!
While most epoxies break loose at 400 F some need to be cured at those temps !! The rotors started out at 6" wide but by the end of the war were 14" wide !!
Special tapes have been used too . Look like duct tape but are far stronger !!

[FrankenMauser]

Glues have come a long way since horsehide and wheat paste. A friend of mine worked helicopter maintenance in Vietnam and told me the skins on the rotary wings were glued on with a special Boeing adhesive. Ever since then, I've considered that the right glue for a job is not to be dismissed out of hand.

Yep. The right glue, and the correct preparation for that glue.

I have no problem using all kinds of adhesives for jobs on firearms. But it needs to be the correct adhesive, and the parts must be prepared well. Failure to prep is a waste of time.

I worked MH-53s. Our rotor blades (2nd/3rd Gen) had a pressurized titanium spar running the length of the blade, with laminated honeycomb and a few aluminum and/or titanium strips to reinforce special areas or to allow for slight bending to trim the blade to fly with the rest.
Everything in the airfoil was attached with adhesives - some ultra-high-tech, some conspicuously low-tech. Some had to be heated within pressure vessels to achieve the correct specific gravity, before being being applied at exactly 63 degrees F, within 8 seconds of the primer being sprayed on; and then cured under pressure at a specific temperature for umpteen hours before a dozen more exacting steps were followed. Others (rubber cement, anyone? ) just needed to be applied to surfaces that had been degreased and well-dried.

It's amazing how long we were able to run those blades between time-changes (over 1,000 hours), given how dynamic a rotor blade is in flight.
But it was also amazing just how quickly a blade would fail if not prepared correctly for a repair (also always using some form of adhesive, of course). A bad repair generally failed within 5-10 minutes during the first check-flight, or during the ground-run before the bird even got off the ground.

My experience has been the same with firearms. If it's going to fail, you'll know sooner than later.