Mock up using one receiver hole and the stock hole in the rail blank end(and a washer or two for spacers/clamps since the hole was bigger than the screw head)
Hand cut to length to be rid of the stock/big hole, then used a Weaver rail as a drilling template;
Drilled, and getting ready to counter sink the holes bigger for the screw heads;
Done and test mounted on the gun;
Just so happened I have a drum for the oscilating sander that is the exact diameter to radius the bottom of the rail end to fit the receiver;
Front mount hole was located, squared and drilled with the same Weaver rail guide as the rear holes, the counter sunk Big to clear any screw I might need to use.
Test mounted, showing the rise/gap to the dovetail filler;
Creative clamping and leveling to drill through the rail into the dovetail mount for alignment, trying Not to drill into the barrel!
Only slightly kissed the barrel, which I actually wanted, to give a slight divot for the end of the mount screw to push into and lock the dovetail piece in place.
Made sure the blank was drilled through all the way
carefully so as to not sand my fingers, or have the sander throw the piece, loosened the fillers fit in the barrel dovetail by sanding the bottom of the filler. Wanted a snug drive in fit, but didn’t want to need a 10# sledge to do it 
Tapped the filler. Also tapped the rail too.
Cut to finish length, spacers gathered and installed, all installed;
Voila! One scout mounted rail and scope;
A few mistakes, but nothing epic, and not much effect on function, although astheticaly it could be better(like for instance the radius on the bottom is off center, and so is the front mount hole in the rail so the whole thing sits off center to the left of the gun… Would fix with just centering the radius I think… Might try that later. But none of it is off very far, nothing the scope adjustment can’t deal with to sight it in.
Also need to go back and touch up the finish, and bevel the front end of the rail a bit for streamlined looks.
Might put a small rubber spacer under the tip over the barrel band. Will see how solid it stays shooting first.
Its good and solid though, you can pick the gun up by that rail…. its rigid too, no flex between mounts, and just a tad if you press down on the rail above the front stock band(talking like 0.002” movement max!)
It points great! Scope sits perfect in height and eye relief, its super natural to shoulder it and instantly have perfect view. The scope adds a little weight to the gun, but this thing being so short anyway, it still has a fantastic balance.
So, 4 hours of slow careful(tedious) work and about $15 in materials… Not bad! Hell of a lot of work to try to save ~$40 on buying the XS rail though… If I want a second one of these, I’ll just buy it! It was relatively easy to do, and loads of fun, a great project… But I doubt I’d go through it again…
All that’s left to do is wait for my new taps to come in, and Super carefully measure/mark/drill/tap the 30–30s receiver at the front to match the Trapper, so the rail fits it. And then fit the dovetail piece to the 30–30, and assemble. Plus find a warm day to go sight the scope in and try it out!
Alaskan, Adventurer, Engineer. 
Is cutting into the barrel safe? Wont it warp up over time?
Yup, its safe. Especially in this case where I only cut about 0.005″ deep at about 0.200″ dia. 😉
But in general yes, its fine, as long as you follow the same rules to shaping any steel that you don’t want to alter the internal stress of; cut slowly, and keep it cool.
Figure they had to cut all the dovetails and cross pin holes and slots in the barrel after it was made, and probably after it was fit to the action in some cases. Also, barrels tend to be a high alloy strong steel, but still a mild steel for the most part… Ie, not a high carbon steel that is super succeptable to heat/tempering/stresses… It has to stay strong/rigid over its life, but it also goes through an extreme amount of stress when the gun is fired, and also a lot of heating and cooling cycle too, without reacting and warping. (and actually they do warp with heat and firing, thus POI changing with a hot barrel)
The one that gets me is how guys can weld, or solder stuff to a barrel without risking warping it… Or weld to an action attached to a barrel… Thats a lot of heat to bleed through a barrel no matter how good the alloy is at dealing with heat and stress….
G.