I know NECG makes an aperature sight that attaches to the existing ruger mount. Have heard good things about this mount. But does the XS sight systems sight attach to the existing mount without mocification. Is this a good sight for the ruger #1. Would appreciate any information.

The NECG aperature attaches to the quarter rib the same way the Ruger scope rings attach, so there would be no modification to the firearm necessary. Having said that, Beartooth member Charlie Z posted here quite some time back that he had put one on his No.1A in 30-06 and was not having any luck with adjusting the sight to his 165 grain loads. The front sight was a bit too short. I think NECG sells a taller replacement front sight for the No.1 to correct this problem. A slower load may work.

NECG makes extremely high quality products that are beautiful, rugged, and reliable. I have a few of their add-ons on a custom 1895 Winchester and am well pleased with their products.

Here's a thread where Charlie Z talks about the sight a little.
http://shootersforum.com/showthread.htm?p=25952#post25952

The only Ruger No. 1 XS sight that I saw on their web page is the Backup sight. And yes, it does require the rib to be drilled and tapped.
I have the NECG sight on my No.1 S .45-70 and for sake of ease of seeing the front sight, went with the NEGC big white dot sight. I can not stand the Ruger front sight (bead way too small for my eyes) and have replaced every single one of them with NEGC sights on the rifles that have sights. What I did was leave the Ruger front sight on, and after I had the load that I was going to primarily shoot, I set the rear sight (NEGC) to its mid position. I then shot for group at my wanted sight in range, 100 yards. Then I calculated how much taller or shorter front sight I needed to affect zero and ordered the white-dot NEGC sight closest to that calculated height. Finally I fine tuned the zero with the rear. Slicker than deer guts on a door knob.

I guess I misspoke. Big Bore seems to have the exact sight you are looking for and had to drill his. My apologies, sorry for the confusion. :(

The answer is dependent on what caliber your 1A is in. The NECG seems to work fine with 45-70. All that I've read with success have been 45-70. I assure you that it does not work with the 30-06 (not at all with avg +2700' 165gr loads and poorly, if at all with heavier, either.)

If you have a 30-06, or other caliber that has Ruger's .435" front bead, I would suggest that you use the XS front sight (which can be had very tall) and the NECG rear peep.

I've got both the XS and NECG peep sight sets (front and rear sets). The problem with the NECG is that the front sight is too low -- their highest offering is the same heighth as the standard 1A sight (.435", I believe), while the line of sight from the rear peep is a good deal higher than the stock rear sight. Obvious problem here. They still only list a .435 as their tallest.

The XS is a nice sight too and does require drilling 2 holes (and tapping one) -- really, a job for a pro. It's sleeker and lower than the NECG and I prefer it, but it's not worth the hassle of mounting unless you have a gunsmith nearby.