Originally Posted by BrowningBanger
20 Q is fine.
Distance to lands was done using the Frankfurt arsenal COAL gauge.
The fact that my bolt would not close all the way without major pressure in which I was not comfortable doing made me extract the round.
If I feed the round as a single, It would only do it on some of the rounds, even those that were supposed to be .100 off of the lands
Wow. Something is screwed up - that diagnosis is free
On the single fed rounds that exhibit this issue, are they still only marked up on one side of the bullet? At 100 thou off, do you see/not see the issue 50/50, less, more?
From your first post I am assuming this is a brand new rifle? Is it a custom or factory? Can you index a case to see if the bullet wear always occurs on the same part of the throat (i.e. Always at 3:00)?
New brass? If previously fired, how was it prepped?
Multiple types of bullets tried with same issue, or just one type and lot?
I agree with Broz that it is unlikely concentricity - I am just trying to figure out what to ask to narrow down the potential issues.