Difference in Load Data Sources

[Sling10mm]

Ok, as part of my quest to look at 10mm Auto carry ammo alternatives after a squib load in my Winchester Silvertips, I decided to consider loading my own. I had done some load development in the Spring that included 180 gr XTP loads, using Accurate #9 and CCI standard and magnum primers. At the time I was doing it more just for fun testing out my new Lab Radar chronograph.

Anyway, I have gone back and picked two loads that had the highest velocities and lowest standard deviation, which turned out to not be the hottest/fastest loads. That is fine since I'm not looking to beat up my guns, but do want something hotter than 40 S&W. The loads were 14.2 gr of Accurate #9 with a CCI 300 (non-magnum) primer, and 13.6 gr of Accurate #9 with a CCI 350 (magnum) primer. When I had fired these in the Spring I recall that they were stout, but not unmanageable at all, and didn't see any signs of over pressure in the cases. I would say the recoil was similar to the factory Winchester Silvertips.

Before loading up more to test along with the Winchester Silvertips, Hornady Critical Duty and Sig Sauer V-Crowns, I wanted to verify that these were indeed good/safe loads, and this is what I found:.

Accurate website/Lee Loading Manual
Hornady 180 gr XTP, maximum load of 13.5 gr of #9 and a Winchester large pistol primer (non-magnum)

Hornady Loading Manual
Hornady 180 gr XTP, maximum load of 14.9 gr of #9 and a Winchester large pistol primer (non-magnum)

Speer Loading Manual
Speer 200 gr TMJ, maximum load of 14.0 gr of #9 and a CCI large magnum pistol primer

Lyman Loading Manual
Winchester 175 gr Silvertip, maximum load of 13.9 gr of #9 and a CCI large pistol primer (non-magnum)

My Nosler manual doesn't have data for 180 gr bullets, just 135 and 150.

So as I see it, my loads are over max according to the Accurate website data and the Lyman manual, but below max for the Hornady and Speer manuals. I'm sure there are discrepancies like this all over the place, but how do you old salts reconcile this. Any other sources of data to look at that would sway me one way or the other? I know the safest thing to do is just use the most conservative data, and again, I'm not looking to damage my guns, or more importantly, myself.

Thoughts?

 

[red_zr24x4]

What are the min charges for all the reference material? How close are they?
I would find where all 4 overlap and use that as my range - min overlap to max overlap. That way you are within spec of all 4 reference manuals.

 

[Sling10mm]

Starting charge weights for Accurate #9 are:

Accurate website/Lee Manual = 12.2 gr (180 gr XTP and non-magnum primer)
Hornady Manual = 11.5 gr (180 gr XTP and non-magnum primer)
Speer Manual = 12.5 gr (200 gr TMJ and magnum primer)
Lyman Manual = 12.5 gr (175 gr Silvertip and non-magnum primer)

 

[red_zr24x4]

Accurate website is only 1.3 grains different between min and max?
And Lyman is only 1.4 grains?

Not much of a spred on either

 

[Sling10mm]

Yes, and the Accurate max load is relatively low pressure at 34100 psi.

Accurate website is only 1.3 grains different between min and max?
And Lyman is only 1.4 grains?

Not much of a spred on either

 

[dugsagun]

I dont mind cross referencing loads for certain rounds to better find that sweet spot of good accuracy and velocity. I usually pick whichever load is using the same brass that i am. IF none are using the brass i do, then i use the bullet makers data.

 

[mac45]

No two manuals are ever going to be identical, because no two test rigs are ever identical.
All the manual tells you is on that day, with that test rig, that's the results they got.
As a general rule of thumb, I have more faith in the bullet manufactures data than the powder manufacturer.

Noticed that both the Hornady and Accurate max loads get approx the same velocity, 1250 fps.
I generally don't worry about velocity, but seeing the same speed from 2 such different loads makes me wonder..... what sort of velocities did you get?
If I was under the bullet manufacturers published max load, AND not over their published velocity, AND (most importantly) not seeing any signs of over pressure in MY gun, I'd be comfortable with the load I had worked up.

 

[Robert Richardson]

It's called " CYA " by company lawyers.

 

[russc2542]

I've also dealt with this: first few batches of reloads were from the lee book: 115gr 9mm 4-4.6gr titegroup. They were peppy on the low end and ran to "holy crap"... I thought titegroup was just snappy till I got a Lyman book that said ~3.5-4gr of titegroup for the same bullet which ranged from light to peppy. Good times! My suggestion would be start between the lowest and overlap and work up.

Test rig, ambient conditions (temp, barometer, humidity), brass, primers, OAL, etc all vary and are all interrelated.

 

[NKBJ]

The differences in all the manuals' max loads are proof that max should be approached very very carefully.

 

[Goodcat]

If a manual calls it a max load, you can safely go a bit higher, but I don't to save powder! CYOA by the company. Personally, I tend to find an average of the max load of manuals and go a bit south of that. That's usually not very hot anyways.

 

[Sling10mm]

I got 1270 fps with 14.6 gr of #9 and a non-magnum primer, and 1250 fps with 13.6 gr of #9 and a magnum primer. That was as high as I was willing to go.

These were all tested out of my Glock 20.

No two manuals are ever going to be identical, because no two test rigs are ever identical.
All the manual tells you is on that day, with that test rig, that's the results they got.
As a general rule of thumb, I have more faith in the bullet manufactures data than the powder manufacturer.

Noticed that both the Hornady and Accurate max loads get approx the same velocity, 1250 fps.
I generally don't worry about velocity, but seeing the same speed from 2 such different loads makes me wonder..... what sort of velocities did you get?
If I was under the bullet manufacturers published max load, AND not over their published velocity, AND (most importantly) not seeing any signs of over pressure in MY gun, I'd be comfortable with the load I had worked up.

 

[mac45]

I got 1270 fps with 14.6 gr of #9 and a non-magnum primer, and 1250 fps with 13.6 gr of #9 and a magnum primer. That was as high as I was willing to go.

These were all tested out of my Glock 20.

Sounds like you have pretty much duplicated Hornady's max load. <grin>
Personally, I work down from there to find the most accurate load, but that's just me.
Most of my guns, the fastest loads ain't the most accurate, and I'll cheerfully give up 30-40 fps to tighten up the groups.
YMMV

As a complete aside, how do you like the Lab Radar?
Really can't justify one, but I AM a tool junkie.....and they look so cool!

 

[Broom_jm]

The reason you do load workups is to reach the conclusion you started this thread with: You found a load, using the bullet you want, that has a low SD and feels/performs like factory ammo. The best load data is almost always going to come from the company making the bullet you are shooting, so you're basically all set. Load up a small batch and do some additional testing.

 

[Leadeye]

Problems I've had over the years with manuals are always on the low end of the listing, erratic performance and a squib once with 2400. I wondered if they actually checked the low end of the scale or just calculated it. My confidence went up in a recent Speer manual where I saw " don't go below" listings for minimum loads with some powders.