how small a grain increment

[LiveLife]

Disclaimer: Following post lists loads below published start charges. Shoot these loads at your own risk.

I haven't worked up a new load in a pistol caliber in several years. My recollection is that I just pick a charge weight in the middle of the book range, test it, and then use that if it works.

I used to think that way decades ago and thought I was just wasting powder conducting initial powder work up at published start charges.

But for semi-auto load development with faster burning powders than W231/HP-38, particularly if you are looking for lighter target/plinking loads, powder burn can be efficient enough at start charges (And sometimes slightly below start charges) to produce accuracy.

I use Promo which has same burn rate as Red Dot per Alliant by weight and published start charge for 45ACP 200 gr LSWC is 4.1 gr - https://reloadingdata.speer.com/downloads/speer/reloading-pdfs/handgun/45_Auto_200_LSWC.pdf

• 45ACP 200 gr LSWC Red Dot COL 1.190" Start 4.1 gr (749 fps) - Max 4.5 gr (831 fps)

Even using longer 1.240" OAL with 12 BHN (MBC Bullseye #1), 14-16 BHN (Z Cast) and 18 BHN (MBC IDP #1) SWC bullets, 4.0 gr charge produces accuracy and light recoil pleasant to shoot even in compact 45 pistols.


When I introduce shooters to 40S&W fearful of "snappy recoil" or for training drills, I use lighter charges of W231/HP-38 and 180 gr bullets - https://www.hodgdonreloading.com/reloading-data-center

• 40S&W 180 gr BERB FP W231/HP-38 COL 1.125" Start 4.4 gr (872 fps) - Max 5.1 gr (984 fps)

With most 180 gr TCFP bullets loaded to even longer 1.135" OAL, 3.9 - 4.3 gr charge will produce 9mm-like lighter recoil to allow shooters to better focus on target while producing acceptable accuracy for training/shooting drill purposes.


Had I started out at mid-range load data, I would have missed out on these great target/plinking loads.


And we all know about bullseye match shooters "powder work down/down loading" for way lighter than start charges to even use lighter recoil springs to cycle the slide.

This Shooting Times comparison bullseye match load development article used JHP bullet with lighter than lead load data to produce smallest groups of the comparison - https://www.shootingtimes.com/editorial/loads-for-the-bullseye-shooter/99418

• 45ACP 185 gr MBC LSWC W231 COL 1.245" Start 5.6 gr (897 fps) - Max 6.3 gr (1,001 fps) - https://www.hodgdonreloading.com/reloading-data-center

• 45ACP 185 gr Speer GDHP W231 COL 1.200" Start 6.6 gr (995 fps) - Max 7.4 gr (1069 fps) - https://reloadingdata.speer.com/downloads/speer/reloading-pdfs/handgun/45_Automatic_185_GDHP.pdf

185 gr Zero JHP and way below published start charge 5.0 gr of W231 at 709 fps produced the smallest 1.28" 15 shot 25 yard group out of comprehensive 55 load comparison - https://files.osgnetworks.tv/11/files/2018/06/45-ACP-BULLSEYE-LOADS-ACCURACY-VELOCITY-CONT.jpg

So conduct full powder work up referencing most conservative load data for the initial powder work up and consider powder "work down/down loading" if accuracy is produced at start charges to identify lighter than published start charge target loads.

 

[lightman]

Usually 0.5 for both rifle and pistol. But the 380 is the smallest cartridge that I load. If I loaded a smaller cartridge than the 380 I might reduce that 0.5 to something less.

 

[Soonerpesek]

Usually 0.5 for both rifle and pistol. But the 380 is the smallest cartridge that I load. If I loaded a smaller cartridge than the 380 I might reduce that 0.5 to something less.

I'm not sure one can put a generic range for pistol, while that jump may be okay for some powders, for me 0.5 would be more than the range from min to max in .380......and 9mm......and 38 spl.....and 10mm heavy subs......

However, I can only speak for myself, so if it works for you----good deal....!!....

 

[JFrank]

Here’s some recent discussion on the subject. https://forum.accurateshooter.com/threads/powder-charge-weights.4081680/

 

[LiveLife]

Here’s some recent discussion on the subject. https://forum.accurateshooter.com/threads/powder-charge-weights.4081680/

Thanks! That's going to help with my precision .223 load development.

And I have the means to resolve rifle powder granules down to a single kernel.

 

[conan32120]

I think it could get one into trouble thinking .7 gn for pistol across the board is ok.

View attachment 1121491

Gather your data and study it before making a decision. If .2 gn exists between maximum and minimum, don’t make such a big step…

load .45acp, .44 special and .357. never had much need to load .25acp