Having never paid much attention to custom rifles, I am trying to pick up a little general knowledge. What is a "Parkerized" barrel?

Hello,
It is a method/system for preventing unwanted rust, corrosion, etc. of a metal surface. Military has used the method for decades and often you will see the dull/matte dark grey, sometimes greenish finish on military weapons.
There are several firms offering such finishes for sporting rifles or refurbishing military rifles. Been told the green, grey, etc. finishes you often see with parkerized rifles is due to the storage in cosomoline/grease which over time changed the color??? Short answer, metal finish method. Trust me, there are books written on the subject by military collectors/fans.

Thank you. I was sure it was going to be some accuracy trick!

Accuracy trick? Don't think so. Parkerizing is a coating, has nothing to do with accuracy.

C'mon now, We all know that DJ had the bore of that rifle Parkerized last Sunday.

HA! I'm glad I missed it and wasn't one of the "also-rans"! He's a trip!