Here are some quotes I copied/pasted from other threads to respond more appropriately on this thread:
JRWhit said:
With the sierra bullets, that data may be only for that specific bullet and not all copper jacketed bullets. Two bullets of the same weight may have different jacket thicknesses, and different load bearing surfaces. The reason to stay away from the sierra data is because it is outside of the normal range for most jacketed bullets. You will also notice that in many cases Hornady XTP recipes have a higher grain weight charge than other bullets of similar design. Using the same recipe for a different bullet, even though they may be similar, may yield higher chamber pressures.
JRWhit, I agree with you.
Different bullet types, design, nose profile and bullet base/bearing surface length may produce different results (chamber pressure/muzzle velocity) even though all other reloading variables such as bullet weight and powder charge remain the same.
There are many variables to reloading and even to chamber pressure testing done by powder/bullet manufacturers as test barrel groove diameters, test barrel lengths, leade/free bore lengths, OAL/COL used, etc. may vary to produce different average chamber pressures for published load data.
Just as factory 9mm barrels' groove diameters vary from .355" to .356"+, test barrels used may vary. I often wondered about why Lyman #49 max powder charges for 40S&W (i.e. 180 gr JHP at 1.115" OAL/COL for W231) were higher than Hodgdon's published max powder charges at longer 1.125" until I realized Lyman technicians used .401" groove diameter test barrel instead of more typical .400". Since then, I suggest to others to use Lyman #49 load data if their barrels slug out to larger .401" but consider using more conservative load data if their barrels are .400".
There are many variables to reloading/shooting so two reloaders using the same bullet and powder may experience very different outcomes depending on the powder charge, OAL/COL, pistol, barrel length, groove diameter of barrel, recoil spring rate, etc.
One load that work well for one reloader and pistol may not work at all for another reloader and different pistol.
Potatohead said:
bds said:
Often accuracy will build around mid-to-high range and most accurate loads at high-to-near max load data. Depending on the powder, sometimes accuracy is obtained at high range and not at max charge
I've always heard most accurate can be found anywhere, often at mid range. Would like to hear your thoughts. This topic has so many variables though.
I love your posts and don't mean to come off snide here but are you sure about this.
Not at all. And I can only speak from my own experience and others' experience.
For full-power loads, I like slower burn rate powders than W231/HP-38/Unique/Universal with my favorites being WSF/AutoComp (and soon CFE Pistol). But the slower burn rate powders tend to achieve optimal accuracy at high-to-near max load data. IMO, slower burn rate powders at lower load data tend to burn less efficient and this may produce more inconsistent chamber pressures that may result in greater muzzle velocity spread that translates to decreased accuracy.
Most reloaders do not load near-max/max charges for their range practice or plinking loads. If fact, I think many reloaders may not even conduct their load development/powder workup to max powder charges as once they determine the powder charge that reliably cycles their pistols, they identify an acceptable accuracy powder charge slightly above that and call it good. The problem with this is the resulting powder charge used may be at mid range when higher powder charges may produce more efficient powder burn for more consistent chamber pressures and greater accuracy.
IME, faster burn rate powders than Unique/Universal tend to produce accuracy when mid-range load data powder charges are used and some powders produce acceptable accuracy even at below mid range load data. It is for this reason why I use W231/HP-38 for 40S&W. With heavier 180 gr bullets, I can produce accuracy even with start-to-mid range load data that provide less snappy recoil for more comfortable shooting and lower chamber pressures that won't bulge the case base.
So depending on the powder's burn rate and burn characteristics, optimal accuracy can be obtained at different load range.
However, reloaders using pistols with oversized barrels/shorter barrels/stiffer recoil springs may find themselves not being able to reliably cycle their pistols with start-to-mid range load data and must use higher powder charges. If more high pressure gas leaks around the bullet base due to oversized barrels, reloaders must use higher powder charges to reliably cycle the slides. And I think this is why we have varying posts of what powder charges work for different pistols on "
What's your go to 9mm load?" thread. While many posted 124 gr plated RN bullets and 3.6-4.0 gr of Titegroup worked in their pistol, some posted below 4.0 gr powder charges would not reliably cycle the slides in their pistols and had to use 4.2-4.4 gr powder charges.
So for some pistols/barrels, accuracy can be obtained at mid-to-high range load data and high-to-near max load data for some others.
