kekozski, Nailed it, simply remove upper and using either sandbags at the range or forearm rest w/ rabbit-ear rear bag, bench the upper solidly, remove bc/b/ch, hold down tight.
Eyeball through barrel and adjust cross-hairs of scope, works well enough to get ya on the paper. Make sure your looking square down barrel and scope, have used this method on many occasions w/ bolt rifles and ARs.
Mike