Thread: Understanding "Nodes"

I've been shooting a 6mm CM with a new barrel. It was producing 40-50mm 100M groups with a stock standard load (41.5 AR2209 behind Sierra 110's - and various similar quantities of AR2209). Gunsmith is standing right behind his work and has checked it, re-crowned and supplied ammo to test, top service.

Last night I shot it with a very small sample of 110's the GS supplied with 39.5, 40.0 and 40.5 of H100V. Bingo - groups of 11, 9 and 18mm at 100M. I didn't crony these loads but the GRT tells me the velocity would be about 2870 fps (ish) from my 24" barrel so not a million miles away from some of the AR2209 loads I've tried.

I'm struggling a bit to understand this, I've not previously encountered a rifle so "sensitive" to a load. I found this old thread ( https://www.nzhuntingandshooting.co....de-yours-6525/ ) which was useful but I'd like to get a bit better "frame of reference".

How common is it for a rifle to go from 50mm groups to sub-moa with a simple change of powder?? Is this an example of "finding a node"??