Sights on topper 410 : rifle sights which fits barrel diameter

[matseguin]

First of all, sorry if the question is already answered, but I didn't find it.
Then, sorry for my poor english, I'm french.

I go to gunsmith this afternoon to take a Topper in 410 bore.
My idea is to put rifle sights on it to shoot slugs (without CNC machined bases), but will it fit ?
I can mesure the barrel diameter, but I can't find any informations about the diameter of barrels which rifle sights are designed to fit.
Example of sights I'd like to buy : Truglo TG958X

Thanks,

[gcrank1]

The radius that is on the underside of some sights can be made a better fit to the barrel by using a dowel with a wrap of fine sandpaper, or even the barrel itself if you wrap the paper farther up the taper than where you want the sight to fit (the paper wrap makes the dia. of round larger than you want for a perfect fit). Some have used new generation epoxies to mount sights. If they are steel you can soft solder (silver solder isnt neccesary).
Your gunsmith should know all this though.

[matseguin]

Thanks.
Finally, I have find someone who can make cnc machined parts for me (in aluminium).
I'll post pics when all the work will be done (in a few weeks/months) and tested.
Have a nice day,