Said above, but I'll repeat it.
You don't want a sporter-weight barrel for a target rifle, any more than one would want a ten pound bull barrel on a hunting rifle that's going to be toted on your back into the mountains.
There's a reason heavier contour barrels are used for target shooting. It's not that they're any more accurate, per se, than heavier contour barrels.
It's that heavier contour barrels allow you to send significantly more rounds downrange when the line is hot without sacrificing accuracy.

With a lightweight barrel, you will need to wait much longer between shots so as not to overheat your barrel- meaning less rounds downrange. The antithesis to the whole idea of "practice".

Continuing to shoot a barrel that's become too hot will not only result in inaccuracy/shot stringing, but do permanent damage in the form of premature throat erosion.

Get a rifle that's commensurate with the intended use and you'll be much happier...