Shooting higher with less powder

[delta1]

I have been reloading for some time now. This is the first time I have run into this.
In reloading for my SSG 69 with the ZFM 6x42 My best group is 175 VLD with 44.0 grns Varget in IMI brass BR2 primer groups run .550 average 5 shot groups.
So I want to match velocity for the BDC of the scope which should be 2550 fps. which comes in at 42.3 grns Varget. Here in comes in the difference. 44.0 grains Varget dead centre at 100 yds. 40.3 grns Varget 2 inches high at 100 yds. all averages are for 3 groups of 5 rounds for all powder charges used.
Question is am I just hitting a barrel node that is producing the higher hits with less powder?
Thoughts on this would be appreciated.
Regards

 

[Manitobahunter]

I think it has something to do with barrel harmonics. I noticed the same thing with my 45-70 with light loads compared to heavy loads. Light ones hit alot higher.

 

[rral22]

.
Question is am I just hitting a barrel node that is producing the higher hits with less powder?

Regards

Short answer is, yes. I know of no way to predict barrel harmonic consequences of changing a load.