After-Action Report: Criterion Barrels, Inc.

[Stockrex]

as the barrel heats up with repeat firing it causes the barrel to rise as it expands thus tweaking the barrel and action at that junction so you get a V shape so to speak not a straight line from chamber to bore/lands...i know it sounds funny but it happens especially when using devcon as your bedding...its basically steel that i would imagine expands a little with heat as well just like steel which would make the problem worse...this is why most ppl say dont bed past the lug with a target riffle.

the barrel can expand/move in any direction, not necessarily always up.
Could the POI moving up be attributed to increased speed of the bullet?

[Das Capitolin]

the barrel can expand/move in any direction, not necessarily always up.
Could the POI moving up be attributed to increased speed of the bullet?

I would agree with you, except for when there's Devcon steel surrounding the first 3-4" of barrel underside. It was molded around the entire lower half of the barrel, so there was nowhere to go but up. According to the chronograph (and drop rate), there was no increase in velocity.

Once the under-barrel bedding was removed, the vertical stringing went away and fouling reduced.

[Stockrex]

I would agree with you, except for when there's Devcon steel surrounding the first 3-4" of barrel underside. It was molded around the entire lower half of the barrel, so there was nowhere to go but up. According to the chronograph (and drop rate), there was no increase in velocity.

Once the under-barrel bedding was removed, the vertical stringing went away and fouling reduced.

ok that makes sense, good you confirmed velocity with chrono.