I also played around with the crimp (.376-.380) and that didn't seem to help clean things up. I've settled in on .3777 as it seems to just take out the bell and the cases will guage in my hundo.
Taper crimp amount is dependent on resized case length and unless you sort your brass by resized length, your taper crimp amount will vary, especially when using mixed range brass.
I usually measure a random sample of brass and will use the shorter case length to adjust my die to aim for .377"-.378" taper crimp (Whether I am using .355", .3555", .356" sized bullets).
My accuracy was consistent sub 2" groups at 12 yards.
To me, accuracy is the latent product of reloading and shooting variables that is sum or composite of other factors.
Think about what produces accuracy, rather consistency which many call precision. (And as reloaders, rather handloaders for some of us, we aim to produce greater consistency/precision in our reloading practice to produce accuracy/smaller groups)
- Consistent powder charge (Let's say charge variance of .1 gr)
- Powder charge large enough for efficient powder ignition and pressure build
- Sufficient neck tension produced by bullet (with long enough bullet base) seated deep enough where case wall thickens
- Resulting consistent bullet seating depth after bumping the feed ramp from the magazine (Let's say finished OAL variance of a few thousandths and no bullet setback)
- 80% or higher case fill of power so powder granules are in contact with primer flash hole after round slams forward into chamber
- To produce consistent maximum average pressures to push the bullet out the barrel
- With consistent enough muzzle velocities to push back on the breech wall/slide of pistol that will induce recoil and muzzle climb
- Ultimately to produce holes on target at range long enough to show these variables
This is what produces accuracy and many may agree that testing at 12 yards may not clearly show accuracy trends as I found, many fullsize service pistols with decent ammunition can produce 1" groups at 7-10 yards, 2" groups at 15 yards and 3" groups at 25 yards.
During my load development and range testing, I deem a load accurate when it consistently produce around 1" groups at 15 yards to test at 25 yards. More accurate loads will produce around 2" groups at 25 yards. (Of course, there's the factor of shooting variables of shooter input so this will need to be worked on and covered towards the bottom of this post -
https://www.thehighroad.org/index.p...-and-discussions.778197/page-10#post-11419509)
So do not accept 1" groups at 12 yards as true sign of accuracy as I would suggest repeated range testing and further load development to produce 1" at 15 yards to repeat testing at 25 yards.