The NEF 223's are hit or miss for twist. The old NEF made versions were all 1:12", then when Marlin bought it out, they went over to a 1:9" for most models, but some of the old stock barrels were still floating around for a few years. Then at one point the Ultralights were 12" twist and the standards/heavy barrels were 1:9"...

I'll admit, I'm a little demotivated to post since you've said that you're "too lazy" to simply run a cleaning rod down the rifle. Not like it's even hard to gain access to the barrel.