I tested some of my first reloads and came to the bittersweet conclusion that nothing I did made any difference.
I worked up in .5gr increments of H335 from 23gr up to 25gr and I was shooting approximately 1.2" groups or better with each combination. Case length was 1.750" and OAL was 2.230" for every round. Dogtown 55gr FMJs
I also conducted another test:
I made up 10 rounds with identical brass: same stamp, same year, same weight. Each round had 24.5gr of H335 hand measured and then re-measured. Case length was 1.750" and OAL was 2.230" for all ten rounds. MidwayUSA "Dogtown" 55gr FMJ bullets. (Group A)
Then I made up another 10 rounds with mixed brass (FC, PMC, AD, REM etc headstamps from different years). These rounds were 24.8gr of H335 as measured by the Lee AutoDisk Powder Measure. Case length was between 1.748 and 1.7515 and OAL was between 2.226 and 2.24 Both of these measurements were intentionally but randomly varied so I could measure their effects. (Group B) I wanted to see if it was worth the extra time and effort to make sure everything was "perfect".
Methodology:
I used a 10rd Magpul PMag for all tests. I sat at a wooden bench and used sandbags to support the rifle. All rounds were fired from a 14.7" 1:7 twist barrel of unknown manufacture. 5.56 chamber with approximately 2k fmj rounds through it.
Temp was 57F with 0-5kt variable breeze. Humidity was <20%. Sun was out and Prairie Dogs were hiding. ;D
I started by firing 10 rounds of PMC X-Tac 5.56 to practice my fundamentals and warm up the gun.
Immediately following the fundamentals review, I fired 5 rounds from Group A at the center of the paper plate. Then I loaded the magazine with 5 rounds from Group B and fired them two ticks (approximately 2 inches) up from the center of the plate. It was when I examined the paper plate that I figured I probably should have fixed my zero before the test.
Results:
Group A may have produced slightly better results with 1 "flier", but it's impossible to say from this test if the extra effort at the reloading bench was worth it. More testing is necessary.
Conclusion:
The results of this test are 100% dependent on my shooting abilities, which are mediocre at best. Maybe a better shooter with a better gun could have given more impressive results.