Read Perklo's thread in the FAQ on his Superlight experience, although his has a wood stock. Also, look for posts by HowardNZ, he has a Superlight that shoots good, also.
I would clean it well with a good copper solvent to get all of the copper fouling out of it, until your patches come out with absolutely no blue or green. If you don't get a lot out, the bore is probably already as polished as it's gonna get. If there is a lot of fouling, after it's gone, polish according to the Sticky info. If you polish with the fouling in there, you'll be polishing the copper and the parts of the bore that didn't collect the copper.....not a good scenario!
The Superlight has a checkered reputation, some good, most bad. The thin barrel doesn't deal with heat real well and the .243 caliber doesn't keep its cool well, even in a bull barrel.
If you're willing to take a $15 gamble, try a Sims Deresonator on the barrel. I've try one on my .243, it made no difference, but it already shoots good. Mac11700 tried one on his b..bo....bol....weatherby, it reduced his groups from about 2" to less than 1" with no other changes, so it may be worth a try with the SL barrel.
http://limbsaver.com/limbsaver/firearms/barrelderes.aspxI've done a lot of trigger jobs on Handis/Ultras/Sportsters, I have 16 frames and 24 barrels, so my experience isn't the norm.....but, my first one took about 2 hours or a little less including making the slave pin. They take well less than an hour now, start to finish. I usually get a trigger that weighs on a lyman trigger scale of anywhere from 2lbs2oz to 3lbs 6oz with a minimal amount of honing and polishing of the pins and bores.
Making a plexiglas template with 3/16" and 3/32" holes drilled in it to clamp on the frame with a hole over a pin to keep the punch from scratching the frame is almost mandatory, though. The Trigger sticky will show you the way. And for more info on R&R of the trigger group, go to
www.perkloafm.com and download his .pdf files for extreme detail of a trigger job.
There have been a couple Iraq vets posting here and on the Marlinowners board, but not for a while.