The smaller the case capacity, and the smaller the bore, the greater the variation in MV with small changes in powder charge weights.
Yesterday I fired 5 rounds each of two different loads in my .223 Rem. It's an AR-15. Everything except the powder charges were identical. The powder charges were weighed on a RCBS Chargemaster, to within 0.1 grain.
Weight-sorted Lake City cases, Rem 7 1/2 primers, annealed case necks, cases hydrosonic cleaned, outside necks turned & primer pockets uniformed & flash holes deburred with K&M tools, cases trimmed to same length & case mouths chamfered & case mouths polished with high rpm turning in steel wool after chamfering, HBN coated bullets, cases all resized with a Forster full length sizing die (custom neck honed to 0.2435" to avoid use of the neck expander after resizing), lubed interior case necks with Hornady Unique resizing wax and finally; all case necks crimped on the Hornady 60gr Vmax bullets with a Lee Factory Crimp Die after seating bullets to depths measured to within 0.001" from case head to Ogive.
First set of 5 bullets fired over triplicate chronograph setup:
27.0gr Hodgdon CFE223 . . . Avg MV 2877fps
Second set of 5 bullets fired over triplicate chronographs:
27.1gr Hodgdon CFE223 . . . Avg MV 2923fps
The 0.1gr difference in powder charge produced a 46fps difference in average MVs. If I ever experienced this with the cartridges and rifles I hunt game with at long ranges, I'd be interested in maintaining lowered tolerances on my powder charge weights. But I've never experienced such large changes in velocity with such small changes in powder charges in the larger capacity cartridges/calibers I hunt game with at long range.
Excellent chronograph conditions yesterday, and no recorded bullet velocity on the 3 chronographs differed by more than 2fps. In other words the extreme spread of recorded velocities for each of the 10 bullets across all 3 chronographs, was 2fps or less.
Of the rifle cartridges I reload, the .223 Rem is by far the smallest cartridge case capacity, and is the smallest caliber. This 46fps change in velocity for a 0.1gr change in powder charge is amazingly large, in my experiences, even with the .223 Rem. I've chronographed many bullet velocities in each of the following cartridges: .223 Rem, .280 AI, 7mm Rem Mag, 300 Win Mag, 30/375 Ruger Improved, 338 Win Mag, 338 Imperial Magnum, 338 Edge, 338 Lapua Improved, and 375 Weatherby.
I MAY see a 5fps change in MV for a 0.1gr change in powder charge in the larger cartridges, or I may not. A 0.1gr change in powder charge is on the threshold of causing a measureable change in MV in these larger cartridges/calibers, in my experiences. I've NEVER seen a 46fps change in velocity with 0.1gr changes in powder charge for 280 AI and larger capacity/bore cartridges.
I suspect the powder charges I weigh on my RCBS Chargemaster are generally measured to a tolerance within +/- 0.04gr, although I'd need a Gempro or something similar to really know. I trickle the last of the powder in with the Chargemaster, and stop when the digital readout changes to the intended XX.1gr charge weight. This would mean my powder charges would have been between 26.96gr and 27.04gr for the 27.0gr charge. And 27.06gr and 27.14gr for the 27.1gr charge.
The OPs initial post stated "I should note, I am not a competitor of any kind. I do take classes to be able to shoot long, but that is for hunting purposes, not competing."
I don't think the OP would benefit by controlling powder charge weights to 0.02gr even if he hunts with the .223 Rem. But if he hunts with the 270, 280, 30-06, and larger capacity cartridges most folks hunt with, the only purpose for measuring powder charges to 0.02gr would be for the satisfaction of being able to say you've set a goal, and attained it.
It's every person's right to decide which powder charge tolerance is acceptable, and to spend their money and time to achieve their chosen tolerance limit. At least in this country. Thank God for that.
I seriously don't understand the basis for your statement. The test was valid, and the results/velocities are what they are. You might try to claim the velocity results are lacking utmost validity to support the cause and effect of 0.1gr change in powder charge on Velocity. I'd love to have SDs less than 10, but it hasn't happened yet. If the lower powder charge had produce 46fps higher velocity, then "no validity" would be correct - something flawed within the test.
