Seemingly contradictory load data - help!

[rbhargan]

After much procrastination, I am trying to get back into reloading. However, I am finding that load data often seems highly contradictory. Deciding to start off with a common round – 9mm 115 gr. jacketed round nosed bullet, using Hodgdon HS-6 powder.

I compared data from the Hodgdon web site and Hornady Handbook (9[SUP]th[/SUP] edition). Both specify a twist of 1:10” and barrel length of 4” and trim lengths of .749-.750”. Hornady uses Winchester WSP primers while Hodgdon specifies CCI 500 small pistol primers.

Hornady’s data for HS-6 powder, using 115 gr. jacketed bullets (FMJ RN and HP XTP – diam. = .355”) is,
5.7 gr. 1,000 fps
5.9 gr. 1,050 fps
6.2 gr. 1,100 fps
6.4 gr. 1,150 fps (maximum load)

Hodgdon data for HS-6 powder, using 115 gr. jacketed bullets (Speer Gold Dot HP – diam. = .355”) is,
6.7 gr. 1,171 fps (starting load)
7.0 gr. 1,234 fps (maximum load)

Hornady’s data lists the maximum load as 6.4 gr. and a maximum velocity of 1,150 fps, while the Hodgdon data *starts* at 6.7 gr. and a velocity of 1,171 fps! The only difference between the two is the brand of small pistol primer and the brand of bullet. Can that really make that much of a difference, bearing in mind that the bullet weights are the same and they are all jacketed?
Feeling very confused – any help would be appreciated, even if it is just “go read this…”

 

[Broom_jm]

After much procrastination, I am trying to get back into reloading. However, I am finding that load data often seems highly contradictory. Deciding to start off with a common round – 9mm 115 gr. jacketed round nosed bullet, using Hodgdon HS-6 powder.

I compared data from the Hodgdon web site and Hornady Handbook (9[SUP]th[/SUP] edition). Both specify a twist of 1:10” and barrel length of 4” and trim lengths of .749-.750”. Hornady uses Winchester WSP primers while Hodgdon specifies CCI 500 small pistol primers.

Hornady’s data for HS-6 powder, using 115 gr. jacketed bullets (FMJ RN and HP XTP – diam. = .355”) is,
5.7 gr. 1,000 fps
5.9 gr. 1,050 fps
6.2 gr. 1,100 fps
6.4 gr. 1,150 fps (maximum load)

Hodgdon data for HS-6 powder, using 115 gr. jacketed bullets (Speer Gold Dot HP – diam. = .355”) is,
6.7 gr. 1,171 fps (starting load)
7.0 gr. 1,234 fps (maximum load)

Hornady’s data lists the maximum load as 6.4 gr. and a maximum velocity of 1,150 fps, while the Hodgdon data *starts* at 6.7 gr. and a velocity of 1,171 fps! The only difference between the two is the brand of small pistol primer and the brand of bullet. Can that really make that much of a difference, bearing in mind that the bullet weights are the same and they are all jacketed?
Feeling very confused – any help would be appreciated, even if it is just “go read this…”

Yes, different bullets have different bearing surfaces, even if they are both jacketed and the same weight.

Use the data associated with the bullet you're loading, but if you start low and work up until your firearm cycles well and you get decent groups, the actual charge weight doesn't matter a whole lot.

 

[Leadeye]

Reloading data has changed over the years. I load 38-40 and one manual lists 8 grains of Unique as the minimum charge with a 180 grain bullet, another says that's over maximum, go figure.

 

[LeverGunFan]

Also look at the cartridge overall length (COL) for these two loads. The Hodgdon data with the Speer bullet has a COL of 1.125 inch, while the Hornady data has a COL of 1.075 inch, or a difference of .050 inch. In general, if the bullet is seated deeper into the case, there is less volume for powder and the pressure will be higher for equal powder charges. So I'm not surprised that the load with a longer COL allows a higher powder charge. Use the data for the bullet that you will use and also use the COL for that bullet. It would be interesting to compare the Speer and Hornady bullets side by side to see how their dimensions differ, so you can see how far they seat into the case.

 

[rbhargan]

I neglected to pay attention to the COL differences. It seems that a good rule of thumb would be to get load data based on the specific bullet you are using and build around that (regarding primer and powder). Bottom line is that there are a lot of variables to take into account.

 

[Sniper 79]

Loading data is only a reference much like a cook book. I usually find an average of all data I find and start there working my way up until I find an accuracy node and it burns clean. If you are still unsure start a thread on what you are loading and ask for help. I bet someone has already done it and has results.

 

[sugarcreekbrass]

I neglected to pay attention to the COL differences. It seems that a good rule of thumb would be to get load data based on the specific bullet you are using and build around that (regarding primer and powder). Bottom line is that there are a lot of variables to take into account.

I noticed this when I started loading pistol ammo, especially when using plated bullets not listed anywhere in a manual. I just found the closest bullet option with COL, then started at the low end. When working up 9mm loads I found out that I had to work up closer to the max to get my gun to cycle. Good luck!

 

[LeverGunFan]

Out of curiosity I ran the two loads through Quickload to see what the differences are. The Hornady load of 6.4 grains of HS-6 fills the available case volume to 91.2%, while the Hodgdon load of 7 grains of HS-6 fills the available case volume to 85.7%. Quickload estimates the Hodgdon load to have a lower peak pressure than the Hornady load, so the data is not as odd as it first appears.

 

[ru44mag]

I have started recently, and am using Unique. I have found a lot of variations in data as well. Mostly I have backed off a little for safety.

 

[ruger44srh]

Using different primers will affect pressures, accuracy. and velocity

 

[bgcatty]

After much procrastination, I am trying to get back into reloading. However, I am finding that load data often seems highly contradictory. Deciding to start off with a common round – 9mm 115 gr. jacketed round nosed bullet, using Hodgdon HS-6 powder.

I compared data from the Hodgdon web site and Hornady Handbook (9[SUP]th[/SUP] edition). Both specify a twist of 1:10” and barrel length of 4” and trim lengths of .749-.750”. Hornady uses Winchester WSP primers while Hodgdon specifies CCI 500 small pistol primers.

Hornady’s data for HS-6 powder, using 115 gr. jacketed bullets (FMJ RN and HP XTP – diam. = .355”) is,
5.7 gr. 1,000 fps
5.9 gr. 1,050 fps
6.2 gr. 1,100 fps
6.4 gr. 1,150 fps (maximum load)

Hodgdon data for HS-6 powder, using 115 gr. jacketed bullets (Speer Gold Dot HP – diam. = .355”) is,
6.7 gr. 1,171 fps (starting load)
7.0 gr. 1,234 fps (maximum load)

Hornady’s data lists the maximum load as 6.4 gr. and a maximum velocity of 1,150 fps, while the Hodgdon data *starts* at 6.7 gr. and a velocity of 1,171 fps! The only difference between the two is the brand of small pistol primer and the brand of bullet. Can that really make that much of a difference, bearing in mind that the bullet weights are the same and they are all jacketed?
Feeling very confused – any help would be appreciated, even if it is just “go read this…”

I would think the Hodgdon ladders would best be verified for your particular weapon if you use a chronograph to test your loads. In fact all of the recipes you mentioned would really require the use of a chronograph to properly dial in the load to your weapon. Otherwise I think you are shooting in the dark.