A LOT of folks around here hunt with 20" .308 and 7mm-08 rifles, some of which are factory carbines like the Model Seven, some of which are youth versions of popular bolt actions, and some of which are factory rifles threaded for cans or brakes. I currently find myself with five rifles with barrels from 16" to 20" in 6.5CM, 7mm-08, and .308Win. The shortest ones are threaded for suppressor use. I've only been hunting 34 years, but I've never seen a 150-180gr .308Win load produce inadequate results on countless animals shot by myself or my hunting buddies. Same actually goes for typical 140-150gr 7mm-08 loads.

If I didn't have any of them and wanted a general purpose hunting carbine that was made for handiness and effectiveness, I'd simply find a .308Win or 7mm-08 stainless 700 or T3 and cut it back to 20". I prefer the standard sporter guns over the pencil barrel factory carbines. Both examples would be light and have good odds of being MOA accurate with little fuss. H4895 is my preffered powder in both of those chamberings with light to moderate-weight bullets, and I've loaded them at full-tilt and at reduced speeds.

This pic is now several years old, but that's a cut-down 20" 700 SPS SS 7mm-08 in a youth ADL stock with one buttpad spacer installed. It's always been a super handy little killing machine. Would likely be the same in a .308Win.

[Linked Image from i.imgur.com]

Now with even more aplomb