M66 Sight Held On With Epoxy

[BubbaBlades]

I bought this modified 66-5 from a forum member knowing the history of its M686 silver soldered sight falling off and being reattached with epoxy. The reattached sight has held up to more than 1000 rounds of .357 magnum and various .38 special loads shot through the gun. There was even a rapid fire test with several hundred rounds being fired as fast as possible to intentionally heat up the barrel/sight. The gunsmith that orignally attached the sight has offered to repair it, however, I am content to use it as is for my own long term performance test. I have posted this item to inform people of this unique use of two part epoxy. According to the epoxy's data sheet, it has a 4000psi sheer strength and is able to handle up to 400F degrees.
Mark

 

[Spotteddog]

FWIW B/B,
Many 2 stage epoxies actually can develop a more positive connection between parts, once exposed to repeated heating cycles.
I don't know it to be an iron clad fact(?) but I believe it may be the way a certain semi-custom defense shotgun operation recommends to fasten their front ramps for the ghost ring set ups. I've had Meprolite Tritium replacement inserts for red ramp front sights that have been held for 10+ years with only Loctite bearing and sleeve retaining formula.

 

[Wayne M]

Great post Bubba and Spotte, thanks for the info and pictures. Very useful stuff.

 

[1911-BILL]

I have a charter arms .38 that I was going to try this on....now I will. Do you know the brand of epoxy used?

 

[dfariswheel]

Use a high quality epoxy like Brownell's.

The "tricks":

Get as close a fit as possible between the parts. Like solder, the tighter the gap, the better the bond.
You can also make "locks" by drilling and undercutting shallow holes in the parts.

Lightly roughen both surfaces by using sand cloth or bead blast with a "sharp" blasting media. This gives the epoxy a "tooth" to bond to.

The parts have to be CLEAN, and then clean some more.

Apply a release agent like a good wax to any where you DON'T want epoxy to stick. This makes clean up of excess epoxy easier.

Get as perfect a mix as possible. You can use a reloading scale to weigh the two components. The better the mix, the stronger.

MIX the two components as thoroughly as possible. I recommend mixing slightly longer then the instructions call for.

When mixing, don't "whip" it, try to keep air bubbles out.

Apply the epoxy to both parts to insure full coverage then assemble the parts.

Put the assembly near a heat source like a window in the summer or on a heat register. AS LONG as you don't get it over 120 degrees or so, you can even put it in the oven or under a heat lamp.
The heat will speed the cure and make a stronger bond.

Allow the epoxy to cure to a rubber-like hardness, then use a brass or plastic "knife" to cut off the excess. If you've properly used a release agent, the excess will peel right off.

Keep the assembly warm for 24 hours for full cure and maximum toughness.

 

[jsmith357]

The post curing of the epoxy is true - it is called b-staging. As to over the counter - it is hard to beat JB Weld.

Jeff

 

[BubbaBlades]

1911-Bill:

The craftsman that did this M66's sight was S&W Forum's own Allen_Frame. He used an epoxy called Wagner's "Epox-A-Leak." It is sold by numerous plumbing/AC supply stores.
I have personally used J-B Weld and J-B Kwik to build up the top of front sights on more than 10 other guns. None of the built-up sights has failed to date. The J-B Kwik is easier to use, however, it does not cure to the same hardness as regular J-B Weld.
Dfariswheel's details of how to mix and use epoxy is the best description of the process that I have ever read. It's like he was looking over Allen's shoulder and taking notes while the m66 was being done.

Mark

 

[Marksman]

I have used JB Weld to attach several front ramps, no failures to date. I have also used JB Weld to repair a cracked base casting on a reloading press, it is incredibly strong stuff.