First of all, look at the application to determine the scope you want. I use a 3X12 scope with Tactical Turrents, on my .223 Ultra. These turrents are calibrated to the bullet weight, speed, and caliber, I am shooting (55gr) and can be dialed from 100 yards to 500 yards. I don't shoot for measured groups, my only concern is that I break a 4" clay target every shot, no matter the yardage.
The advantage to a fluted barrel is that they cool faster, but you have to remember these guns are not designed for target shooting. They are hunting rifles, designed to place that first shot where it needs to go. Maybe a second or third if you don't do your part. But after that put it down for a while, accuracy has gone right out the window, as the barrel has heated up and will start stringing the shots.
As to modifications, all I have done has been to put an O-ring under the forearm, mounted a good scope, and painted it white. I use it for preditor calling in the winter in snow.
As for getting extra barrels, Yes you can, but I no longer think it is a good idea. When I first got my first Handi Rifle in 30-06 I sent it back and got a .223 and 20ga barrel. Then I found that every time I changed the barrel the point of impact changed, and I had to resight the scope. Now if I had been shooting at 100 yards or less that would have not been a problem, and resighting would not have been required. But I never know how far the shot will be when it presents itself. Therefore I no longer change barrels, except on my shotguns. As cheap as these guns are I just buy the whole gun for the caliber I want. That way once I get it set up nothing changes.
I got a .243 for my son when he was 10. His mother sent the reciever back and got a 45-70 barrel, and the .50 cal barrel for him. Today the 45-70 barrel has been on the gun for the last 6 years, that is the only barrel he wants to shoot with the gun. He thinks of that gun as a 45-70 and if he wants to shoot a differant caliber he gets a differant gun.
