The gap is so tight on the 15-22 I can see where solid contact would occur with the barrel using a bipod or rest. Especially leaning into the rifle. Does is really matter? No idea. Those experiencing improved groups and accuracy, I take their word for it.

I chose not to use my drill press. Being a bit ocd, I put a stepped bit in my little vise and with firm / even (but not stupid firm) pressure, rotated the endcap. What ever step I started with, I went one bigger which appears to have given me a 1/32" gap. Calipers would say different but it's extremely close to 1/32". Had the wife hold a mirror out front while I rested the handguard on the back of the couch with what felt like my normal (pretty much none / just the weight of the rifle) firing dynamics are. I saw no movement of the handguard in that static position. I then did the same resting the barrel with same results.

Firing the weapon could produce different results but I don't believe there's any contact between barrel and handguard. The thing's darn accurate out to 50 meters. Haven't fired enough beyond that to comment.