Re: DPMS 308
The trigger was horrible in my Lr-308. I replaced it with a RRA NM 2-stage, and I love it now. You can usually find one for under $100 if you search, it dropped right in, and took about an inch off my groups. If I was going to upgrade over the RRA trigger, I would get a SR Gold trigger from American Trigger Corp. Supposed to be the best there is.
If you decide the Lr platform would work better for you, all you have to do is replace the upper. Mine was a 300 RSAUM when I bought it. I decided I'd rather have a .308, so I ended up trading mine for one a guy had on Gunbroker.
If you like the Sportical, stick with it. But if you're going to make a change, it's better to do it before you start building. Just my opinion.