Want to install ghost ring on my 870- questions

[zimm17]

I have a factory 870 21" barrel with adjustable rifle sights on it.

I want to intall a ghost ring rear. It looks like I can use XS sights rear ghost ring and it sounds like their tritium front sight replaces the factory one on my barrel?

Can anyone confirm?

Where can I get a drill and tap set to do the sight base myself?

 

[dfariswheel]

The XS rear will fit fine.
The front is a standard US dovetail and will fit the front base.

You can buy the correct taps and drills from Brownell's as well as the sights:

http://www.brownells.com/default.aspx

The difficulty in installing the rear sight is getting the base and holes properly centered on the barrel. You'd think that couldn't be that hard and any gunsmith could do it easily.
However over the last few years I've seen several shotguns with botched up rear sight drill and tap jobs.
These ranged from bases off-center or under the base was one or more extra holes where the installer had botched up and had to drill more holes.

 

[zimm17]

My barrel has adjustable rifle sights on it. No bead. Will it line up, or will I have to change out the front sights?

Looks like this: http://www.midwestgunworks.com/page/mgwi/prod/remington-870-barrels/24545

 

[dfariswheel]

It may line up.
The rear should have enough adjustment to get on target.
One thing to watch is getting the rear positioned in the right spot.
If you move it down the slope of the rear of the receiver, you can get it so low the gun will shoot very low.

Mount the rear sight and set it in the middle of the elevation adjustment range, then shoot it for target.
If there's enough adjustment up or down to get on target, you're good.
If not, buy a higher or lower sight as needed.

The standard barrel mounted rear sight's base is brazed on the barrel. Due to the difficulty in getting the base off and having to refinish the barrel, I suggest just removing the adjustable parts of the rear sight and leave the base in place.
It shouldn't be any problem with the ghost rear.