Help understanding drastically different load data

[johnandersonoutdoors]

Speer Manual 13th edition
9mm 125grain lead round nose lists Unique range 4.1 to 4.5 grains (COL 1.130")

Alliant Powder Reloaders Guide (2000 edition)
9mm 125 grain lead lists a max charge of Unique at 6.0 grains (min COL 1.150")

I know any change in COL can mean increase in pressure and if you shorten COL then it makes sense that powder charge would need to go down. Speer manual lists a specific bullet and I do not know bullet that Alliant manual is referencing.

Still very surprised to see difference in max load of 4.5 versus 6.0.

What do you guys think?

 

[lckdnldd]

The short answer is: Although the powder may be the same, each powder/ bullet manufacturer and or distributor uses different test equipment and load components for their testing.

 

[243winxb]

Could be the difference in bullets. Speer soft swaged vs hard cast bullets.

 

[Sunray]

Different test equipment, load components and the powder lots used in 2000 would be slightly different than those used now. Alliant shows 5.8 of Unique as max for a 124 grain(That's close enough. One grain won't matter.) jacketed bullet out of a 4" barrel with 1.120" as the OAL, on their site. No cast bullets shown.
The 1.130" OAL is shown as for a 147. Hodgdon gives 1.169" for a 124.
Speer's Manual is currently their 14th edition. It'll be slightly different too. Number 13 dates from approximately 1998.

 

[gonoles_1980]

Pure guess on my part, but Speer bullets are soft lead, many manufacturers make hard lead. Could be the difference between hard and soft lead (as mentioned above). Check the bullets they used.

I don't see any lead loads in my 14th Speer addition, and I don't see a 125gr lead load in my Lyman book. Went to the alliant website, didn't see any 9mm lead loads for Unique.

I don't have any 9mm lead recipes, I load all copper plated for my wife.

 

[noylj]

I have never seen any load differences between hard and soft alloy--they shoot to very much the same velocity for a given charge. One area where I have seen a slight difference is between a one-groove cast bullet, a two-groove cast bullet and a no-groove swaged bullet, but it isn't a big difference. I expect some have seen a slight change in load for the new no-groove cast and coated bullets.
Different gun.
Different lot of powder.
Different primer.
Different case.
I always start with the lowest start load I find and work up.

 

[WestKentucky]

This is why I don't put much stock in max and min loads. True enough I try to find a nice load within published ranges but I have been known to get out of the recommended box. Each gun has different chambers (tight, loose, short, long) and each brass manufacturer has different dimensions on the brass. Couple those variables to variances in primers and huge variances on bullets and you get what you have....a set of variables in which results can be drastically different. The books are great for telling you what is an accepted safe range which you should attempt to work within, but if you eliminate any variables by using a single product then you hone in on what works for you and your gun. It may be within the printed range. It may be slightly more or slightly less. The important thing is not to move around too quickly on the scales. Small changes can mean big differences, especially if you are using unsorted range brass.