Load Data from different sources. Who is right?

[noobie]

Comparing data from 2 sources. Can someone explain the variation between the 2 sources? Who do I go to for reliable data? The velocity is quite different as well as the max between the 2 companies. Do I have to buy a Chronograph? Will speed tell me pressure? How do I know the max load other than determining the bullet won't fit in the case if I put that much powder in(I don't use this method at all!). Tried several max load shots using the Hornady book and everything looked and felt good.

150 gr. 30-06 SPRG IMR 4064

Hornady 10 edition book:
2500 44.7 gr.
2600 46.9 gr.
2700 49.1 gr.
2800 51.3 gr.
2900 53.4 gr.
2950 54.5 gr.
3000 55.6 gr.

Hodgen Resource Website:
2743 47 gr. Start
2928 51 gr. Max

 

[riflewoman]

Each of the reloading data publishers report load data that they shot. But that was in their rifle in their lab on one particular day. Your rifle is different and will develop velocities and pressures differently. You need to be prepared to adjust the load as your rifle reacts to them. You might not ever reach the max charge in Book “A”. And Book “B” might be several grains below what yours seems to handle fine. BUT, BEFORE YOU go beyond any published data you have to be able to read excessive pressure signs.

 

[HTSmith]

I've often wondered about the same thing. From personal experience the red lights start flashing at about 53 Grains of IMR4064. The Hornady test rifle must have had a long throat and/or a loose bore. Riflewoman makes a lot of sense.

 

[Darwin]

Different Lot #s of powder will vary in burn rate and pressure as well. These variations in equipment and components and temperature are why we all say "Start low and work up".

 

[ShootDots]

Barrels have minimum and maximum SAAMI specifications. Freebores vary literally from one reamer to the next, from one testing facility to another. Various lots of powder. Then most of the manuals go in 100f.p.s. increments. Some barrels with either a tighter or "looser" barrel will or will not reach the next 100 f.p.s. without excessive pressure. Then who knows how well they maintain their barrels? They could be new or used or completely firecracked up! Who knows.. All the above will contribute to the expanse of charges between manuals..

 

[Homerange]

Comparing data from 2 sources. Can someone explain the variation between the 2 sources? Who do I go to for reliable data? The velocity is quite different as well as the max between the 2 companies. Do I have to buy a Chronograph? Will speed tell me pressure? How do I know the max load other than determining the bullet won't fit in the case if I put that much powder in(I don't use this method at all!). Tried several max load shots using the Hornady book and everything looked and felt good.

150 gr. 30-06 SPRG IMR 4064

Hornady 10 edition book:
2500 44.7 gr.
2600 46.9 gr.
2700 49.1 gr.
2800 51.3 gr.
2900 53.4 gr.
2950 54.5 gr.
3000 55.6 gr.

Hodgen Resource Website:
2743 47 gr. Start
2928 51 gr. Max

It's not about which one is right as long as the printed loads we all refer to are safe !

How is a component manufacturer to know your intended use ? They really have no idea so they stay on the safe side to limit culpability.

Lets say I wanted to load 150's in a 30-06 for a teenager.....well I'd be using 30-30 class flat nose projectiles to ensure good terminal performance and be poking them down the tube @ 2500 fps so to NOT get the kid kicked around and be scared of the rifle.
Horses for courses.

 

[rwj]

Do I have to buy a Chronograph? Will speed tell me pressure?

So many “accessories” to buy when one starts down the reloading path! I’d suggest placing a chronograph in the top 10. Magnetospeeds are reasonably priced, used ones even more so, watch the classified adds. Once obtained, one can establish the velocity achieved by each load combination for your rifle. As other posters have stated, published load data is a starting point and not necessarily reproducible in your equipment...

 

[Webster]

Comparing data from 2 sources. Can someone explain the variation between the 2 sources? Who do I go to for reliable data? The velocity is quite different as well as the max between the 2 companies. Do I have to buy a Chronograph? Will speed tell me pressure? How do I know the max load other than determining the bullet won't fit in the case if I put that much powder in(I don't use this method at all!). Tried several max load shots using the Hornady book and everything looked and felt good.

150 gr. 30-06 SPRG IMR 4064

Hornady 10 edition book:
2500 44.7 gr.
2600 46.9 gr.
2700 49.1 gr.
2800 51.3 gr.
2900 53.4 gr.
2950 54.5 gr.
3000 55.6 gr.

Hodgen Resource Website:
2743 47 gr. Start
2928 51 gr. Max

I shoot a 6BR. People on this website has said they can get 3800-3900 fps with 55 gr bullets. I know from experience and my chronograph that it’s hard to get above 3650 fps. Tried many suggested powders. Every rifle is different. Need to work up loads and know the signs of pressure. I go for accuracy and decent fps. No reason to push the limits.

 

[Zero333]

Exactly what others have said...

Things that make the difference...

Brass (capacity and hardness)
Primer
Lot of powder
Bullet (same weight, different profile)
COAL
Barrel (rifling type and erosion)
Chamber (freebore and min/max saami specs)
Action/receiver


-Start near the starting loads and work up accordingly.

-Read the manual (the stuff before the load data).

-Learn how to read signs of pressure.

-Understand outside temp plays a big role in pressure.

Following article is the best I've read about understanding and knowing how to read pressure signs...

https://www.primalrights.com/library/articles/understanding-pressure

 

[Rem06]

they are reference manuals, they are all correct.

 

[rammac]

Use the manual that was published by the manufacturer of the bullet you are using. Most people don't realize that bullet shape effects pressure so assuming that the same powder charge will produce the same pressure for all bullets of the same weight isn't true.

 

[Rem06]

Use the manual that was published by the manufacturer of the bullet you are using. Most people don't realize that bullet shape effects pressure so assuming that the same powder charge will produce the same pressure for all bullets of the same weight isn't true.

Bearing surface

Do I have to buy a Chronograph?

barrel length will change velocity

everything is a reference

headspace, case length, bullet jump, all the above

definitely read the front of the book before just jumping into the load data

 

[Reloading Guy]

This might sound strange, but it totally doesn't matter that the 2 books are different. You would load up ~3 rounds at like starting of ~48 grains, and keep going until satisfied. The thing about loading books that is left out is you do not know the exact internal capacity of the brass. The brass is a big difference in brands and lots. One brand of brass could be several thousand PSI higher pressure in the load than another, with same load, bullet, OAL. The only thing that matters, is you start at a safe area, and work up to whatever you want to do. How safe it is is only up to you, that is your responsibility.

 

[Daddymac]

Load manuals are more of a guide than the gospel, as others have stated, our rifles are as different as we are. If you are a beginning reloader, start low and slow, be safe, learn to read the information your brass and rifle are giving you.

 

[rammac]

Bearing surface


barrel length will change velocity

everything is a reference

headspace, case length, bullet jump, all the above

definitely read the front of the book before just jumping into the load data

Not just bearing surface, it's also volume. Bullets of the same weight from different manufacturers have different profiles that results in different usable case volume. So the pressure will be different due to bearing surface friction and usable case volume.

 

[Uncle Ed]

If the reloading manual lists a specific firearm used in load testing a strain gauge is glued to the barrel to register chamber pressure. And a cartridge of a known chamber pressure is fired to calibrate the strain gauge setup.

In some manuals they list a universal receiver and a pressure test barrel using a copper crusher or transducer for chamber pressure. And these pressure test barrels have the chamber and bore cut to minimum dimensions to obtain the highest possible chamber pressures.

And then you simply have variations in firearms manufacturing, example the throat in my Savage .223 is longer than the throats in my AR15 rifles.

And there is a reason why the reloading manuals tell you to start at the suggested starting loads and work up.

And did you ever wonder why the Quickload data varies until you tweak the burn rate in Quickload and adjust it until the velocity matches your chronograph.

And in this very forum the photo below was posted and the OP stated he increased the load until he got ejector marks and then backed off 1 or 2 grains. Meaning he found the elastic limits of his brass and backed off, and this varies between the brands of cases and how long you want your primer pockets to last.

And in another forum today a new reloader asked if he could use his .303 British .312 bullets in his new 30-06 with a .308 bore.

 

[piaa1209]

For a hunting gun, 50 grns of 4064, 150 sierra spbt, br2 primers. Might not be the fastest, but its deadly on deer and drives tacks. This is out of a pre 64 winchester

 

[Bojo]

I always enjoyed the posts that claim "just fill it to the top and scrape the powder level follow it up with compressing the powder when seating the bullet. "

 

[Twoboxer]

IMHO, the answer to OP's question is simple: NEITHER of the max loads listed is correct. The published data are NOT recipes, they are TEST RESULTS.

Your lot of powder and primers (brand too), your rifle's actual chamber size, your brass (brands and/or lots), your lot of bullets and variations in shape/composition from what was tested . . . all of these WILL be different than what was tested to produce the printed data. Your barrel length and COL are also important. All of that means the published data will only match your actual results by accident.

So you can't simply pick a max load. That's why you "work up a load", starting below any published max, while looking for pressure signs. Some of us look for accuracy as well, since the most accurate load is very often not a "max" load.

Finally, no one can tell you what your max load will be without a pressure gauge attached to your rifle shooting your loads. Nor can they tell you what powder charge will be most accurate. You need to work up your own load . . . safely.

 

[riflewoman]

And in another forum today a new reloader asked if he could use his .303 British .312 bullets in his new 30-06 with a .308 bore.

In actuality, the bullet will be fully engraved and sized down to groove diameter by the time of peak pressure so it wouldn’t really affect his 30-06 that much. PO Ackley chambered a 30 caliber barrel for 8mm Mauser then promptly fired a German WW2 Service round. The case ejected normally and had only “mild” evidence of any pressure.

Accuracy might suffer a lot with these mismatches, but unless diameters become extreme, peak pressures won’t change that much, if at all.