Your jinked mate, give the sport up and go find another one that is perhaps hex free lol
Or maybe your just a perfectionist and notice more because of it ?
I've noticed a Hw35 .177 with a tight spot in the barrel about 2/5th up and a early mk2 Hw77 .177 with a choke so tight at the muzzle, I'm sure the pellets were coming out less than 4mm.
Honing comp tubes is a option, just practise on a piece of spare tube first so you can gauge how much metal your taking off with it. ;-)