guntercb,
Welcome to Graybeards!
If you go to the FAQ's and scroll about 2/3 of the way down the page you will come to "Scope Bases". You might have to wait for a minute or two for the pictures to load. The scope rails are a universal fit on any factory drilled & tapped H&R/NEF rifle, whether that be a Ultra/Handi/Huntsman/Sidekick. All have three holes, and are spaced the same distance apart. You will want the H&R/NEF Standard rail, the discontinued Ultra rail was made for the very long scopes used on varmint rifles. Not needed on a Huntsman/Sidekick.
FAQ's.
http://www.gboreloaded.com/forums/index.php/topic,26264.0.htmlGet the standard rail w/extension from Customer Service or elsewhere (see FAQ's for othe locations) like Brownell's etc., then any Weaver style rings will fit it. These can be Warnes/Leupolds/Burris/Millet, or whatever brand you prefer. Depending on the ocular bell diameter on your scope, or where the hammer is positioned after setting your eye relief, it will determine what height rings you will need. Highs are usually a safe bet, but different manufacturers have different heights, they are not universal. You may be able to get away with mediums from some manufacturers. Like I said the height of the rings and the dimensions of the scope will be the determining factor.
The Hammer Spur and Hammer Extension are not the same thing, although they are frequently referred (myself included) to as being the same thing. Hammer Spur Extension would be the correct terminology. The spur is the part of the hammer that you use to cock it, also what you attatch the hammer spur extension to.
If you want a rail other than H&R/NEF or the Leupold, check the links in this thread, there are several. Remember, you will still want/need a Hammer Extension. Personally, I would get the Standard rail w/hammer extension together.
http://www.gboreloaded.com/forums/index.php/topic,160114.0.htmlNo experience with the Carlson's Hammer Expander.