I was looking hard at the internet photos of the Mossberg set for $70.  Now I know they are designed for a Mossberg, but it looks like the front sight (which I assume is epoxyed or soldered on, right?) is curved for the 12 ga barrel diameter.  How close would it be to other 12 ga pump shotgun barrels?  Like my Win 1300?  I'd imagine it is VERY close if not right on.

Also, if I have to drill and tap my Win 1300 receiver ANYWAY, why not mark the holes from the Mossberg rear sight on my Win 1300 receiver and drill and tap THOSE holes, then install the Mossberg rear sight?

Anyone have first hand experience handling the Mossberg ghost ring sight set like I described?  Does this sound possible?  I am VERY tempted to purchase the $70 set and try it out.  I guess I could re-sell them for atleast $50, and only risk $20 if it looks like it really will not match up at all...thoughts?

www.mossberg.com/acatalog/conversions.htm

Everything you said holds true, EXCEPT......
The front sight should be brazed on.

This takes heat above 1100 degrees, and that means a complete refinish for the barrel, and a bore polish.

If done improperly, you run the risk of damaging the inside of the barrel.

You can attach the front sight with soft solder by the "sweating" method, and the sight will stay put fairly well.  
However, any real rough use and the sight goes by-by, since soft solder isn't as strong as silver or brass brazing.

I have sweated front sights on Remington 870's and they stayed put for many years, AS LONG as they don't get bumped.

The key to a strong soft solder job is a tight fit between the base and the barrel, which I'd assume the Mossberg front would be, even on a Winchester.

You have to remove ALL finish down to bare metal on both the sight and barrel, but ONLY within the precise areas the sight will be attached.

Next, use a silver BEARING soft solder.  This IS NOT real silver solder or braze, it's a soft solder with about 3% silver content to add strength and prevent tarnishing.
It melts and flows at about 450 degrees, where real silver solder flows at temps over 1100 degrees.

Epoxy is a total non-starter.

Hmmm.  Well, that DOES give me an excuse to re-finish my Winchester in OD!  Which I've wanted to do for some time.

What I can recommend here is to buy your silver braze from Brownell's.
Depending on how close the ramp fits the barrel, you can use:
STL 1205, #322-100-650.  Which melts at 1145 and is for tight fitted parts.
STL 1260, #322-120-650.  Which melts at 1220 and is for ramps that don't fit tight.

This comes in a pre-mixed paste.

If the barrel support ring or ANY other parts of the barrel are close to where you'll attach the sight, use heat control paste and heat-sinks to protect them or they may come loose from heat spread.

Use enough torch.  
You want to heat the barrel and base both, as fast as you can, to prevent head-spread.

The tough part is getting the base located SQUARELY on top of the barrel.
I've looked at them for hours, and they still come out off-set to one side.

One trick I've used is to hang a heavy weight, like an old copper soldering iron or something else heavy but with a narrow "point" from the ceiling.
Allow the "pointy" end to rest on the base, but with not much slack.
This will work as a clamp to hold the base in position, and prevent everything from falling apart when the solder melts.  
When the braze does melt and flow, the weight presses it in place insuring a tight bond.

The narrow end resting on the sight base prevents the weight from wicking the heat up into it.

Once you've got it brazed, let air cool, NO quenching in water.

After it's cool, scrub down with HOT water, soap and a brush. Inside the bore too.
Then clean up excess flux and solder with wire brushes and needle files.

Use steel wool or some strips of synthetic "Scotch-Brite" pads wrapped around a worn shotgun brush and chucked in an electric drill to polish the bore back up. Run the drill at medium speed and keep it moving up and down the bore.

I recommend shooting it with full-power buck or slugs to "test" the bond before coating it with a new finish.

Good luck, and post a picture of it when it's done.

Back when I had my 1300 Defender, I considered these.  They would not needed soldered or brazed on and look quite rugged.

www.brownells.com/aspx/NS/store/ProductDetail.aspx?p=9203&title=TACTICAL+SHOTGUN+SIGHTS

That would certainly be a LOT easier, and less stressful to the barrel.

Gunsmithing has progressed, and we're getting more and more reluctant to heat up gun parts.

It may not harm them, but it sure doesn't do them any good.

You know, I can get a Mossberg 590 with synthetic stock, extended mag tube, durable matte blk finish AND ghost rings sights for mid $300.  OR I can spend $150 on ghost ring sights, another $50 on syntetic stock and then another $100+ on refinish of my shiny blued, wooden stocked  Winchster.

Sooooo $350 and I have everything I want AND a second shotgun....or approx $300-ish and my Winchester is modified like I want...

Seems like an obvious choice.  I'd love to pimp up the Winchester 'cause I don't see many done up, but the Mossberg seems like the better decision.....

Thanks for all the input.....still gotta decide.

Cheers!