(1) In terms of precision, plated bullets aren't great. Switch to ACME or any other number of coated lead bullets or Precision Delta .355 JHP or (my ShadowLine prefers) their .356 (sold as .38 Super) FMJ, OR RMR jacketed (which I have never used, but seem quite popular). But at the end of the day, finding the bullet your pistol likes is a big part of it, and bullet to barrel fit is huge.
(2) I have found "accuracy nodes" with my ShadowLine that vary by bullet weight. Regardless of bullet-powder combo, groups with 124/125gr bullets would see group tighten somewhere in an average PF range of 132-134, and 147gr bullets would tighten up around 137. My pistols with polygonal barrels do not show accuracy nodes like that, but my CZs do.
Your PF is no big deal, and you are correct, you will never notice small differences. If you load and test over a chrono and know your velocities, go back and calculate extreme spreads in terms of PF, and you will see your ES in terms of PF is probably 4, 5, 6 or more. If you can't notice that shooting over a chrono, you will never notice twice that running a course in your action shooting sport of choice. ;)
In terms of upper or lower end (or middle, whichever) of a load range being more accurate, I know people I respect and trust when it comes to loading who have found such trends, but I have not found them at all. In my testing, specifically where I noticed my CZ trending to accuracy being tied to velocity by bullet weight, I specifically tested faster burning vs slower burning powders to see if there was such a trend, and in all cases, the bullets tightened up in particular velocity ranges, NOT at particular ends of the powder charge range. The only trend I have seen there is that there tends to be a load at and above which SD and ES drops is markedly improved, I would assume because that is the point where I start to get a fast, efficient pressure seal and stop blowing powder past the bullet into the barrel where it doesn't contribute to moving the bullet.
And that's my 6 or 7 cents. ;)
Factory ammo (fed syntech) in the same new gun is very accurate….hotter obviously.
(1) In terms of precision, plated bullets aren't great. Switch to ACME or any other number of coated lead bullets or Precision Delta .355 JHP or (my ShadowLine prefers) their .356 (sold as .38 Super) FMJ, OR RMR jacketed (which I have never used, but seem quite popular). But at the end of the day, finding the bullet your pistol likes is a big part of it, and bullet to barrel fit is huge.And that would be my first thoughts too.
Just picked up some .356 Zero JHP to test, based on IDescribes observations. I’ve noted some .357 lead bullets I used in past were super accurate in my Shadows. But I don’t load lead or coated lead anymore. Prolly stick to JHP or CMJ going forward. Hence the .356….I also love the bullets from Zero [ https://www.rozedist.com/ ] and used them for a log time, but their supply was limited and like PD, they would run out of stock regularly. In fact, it was my first order from Zero that started this whole "watch your OAL in CZ chambers" thing, and began my entire involvement with this Forum !! What I wanted was simple FMJ bullets, but they were OOS, so I ordered a bullet designed for 357SIG (the only other 0.355 bullet in stock). The OAL on that first order worked out to be ~0.970", and so I had to sell them to a shooting buddy and reorder from Berry Mfg. Here's the original, very first photo I took for this Forum...
I found that a really good crimp will keep the velocity and accuracy tighter then a mediocre crimp. I use a lee factory crimp on every cartridge I load from 380 to 300 win.
Is this a round nose specimen?