Large difference between reloading Data?

[engineer40]

I was surprised to see such a large difference between suggested powder weights between reloading data sources.

I was using my Lyman manual yesterday for my first loads with a 30-06. It suggested for 168gr bullets to Start with 43 grains of IMR4895. This was also bold as their "possible most accurate" loading for the 168gr bullets. So that's where I started and loaded some ammo exactly like that, 168gr bullets with 43 grains of IMR4895. Lyman has the Max load at 48.5 grains.

Since my reloading equipment is new I was reading back through some of the documentation again and noticed a nice chart on the back of my documents for the Lee Dies. It had IMR4895 Starting load for 168gr bullets listed at 48 grains. And Max was 51.2.

I checked IMRpowder.com and it matched up with the chart on the Lee Dies.

I realize there might be some variation between load data but this seems too extreme. The Lyman data says the Max load is the same powder weight as the Starting load in two other places?

Is it normal to see variations this large in the data? Are these guys just guessing?

Is my rifle safe to shoot that ammo I loaded with only 43 grains since that is so light compared to other data sources Starting loads?

Thanks everyone! I appreciate any feedback.

 

[Mikecr]

Think about it, and about what you're doing here.
Of course they're guessing. How could they possibly know anything about your chamber/bore/bullets/brass/powder? They don't, and neither do you initially.

As a reloader the first and most important thing to know is that every bit of these abstracts land on YOU to define -locally. This is just what all them manual disclaimers are telling us.
Basically, manuals are just anecdotal guides, swayed by legalities, and merchandising, etc..

People who follow manuals blindly are dangerous.
Probably seems irrational, but IMO, these type of people are likely reckless in all aspects of their lives.

 

[Bbear]

Different manufacturers use different 'testing' procedures. Some fire all of the bullets with many different (and suitable) powders through a 'test' barrel. Others use actual factory made firearms. Barrel lengths differ from maker to maker. Then you add in the fact that some will use computer programs to give them the 'range' of loads that fit a specific caliber/cartridge/powder/primer combination. (Think of someone never having loaded a single cartridge starting out using nothing but QuickLoad. Then deciding they liked the looks of that whizz-bang speed that just happens to be a bit too much and go from there).

As Mikecr stated, they don't have any idea of YOUR specific firearm's dimensions. The books are guideline that only your personal testing will show what works in your rifle and doesn't.

I have too many times tried someone else's 'perfect' load in one my rifles and find them shooting patterns instead of groups. To the point if I don't load it myself, I don't shoot it. (especially after I was told by one acquaintance that he just poured the IMR4831 into a bowl and scooped the case full then seated the bullet).
And yes, I have had store-bought, factory ammo that was too hot to shoot. Last batch was some re-called factory 5.56 ammo that required the bolt to be replaced by the factory.

On top of all of this you have to toss in the lawyer angle. None of the people that put these out want to get sued and have hired lawyers to help stop that. That's brought us such wonderful inventions as the L-lock on Remington 700's, Narrowed powder charge ranges, reduced max loadings, trigger locks with every firearm and many others.

Looking at the Hodgden online info, I wouldn't start as low as 43. Though it MAY be safe, I'd feel more confident starting with the 48 gr starting load. You may also notice that the max load of 51.2 is only 3.2 grains more and you 'only' gain 140 fps in speed. You also gain nearly 9000 PSI pressure in that 3. 2 grains more powder. You might find an accurate load, but there are other powders that may do better.

One last thing, do NOT confuse IMR 4895 with H4895. They are TWO COMPLETELY DIFFERENT POWDERS. The starting load for H4895 is 43 grains! Check your books and make certain you aren't confusing the two.

 

[engineer40]

Thanks for the fast responses.

I do have 5 different rifle powders on hand and 4 that are in loading data for a 30-06 for both bullet weights I currently have to test with. I initially choose the IMR4895 because the manual showed it "may" be an accurate load for the 168gr bullets I am starting with. I do plan to also test the other 4 viable powders with both these 168gr bullets and the 178gr 30 caliber bullets I have.

I don't feel that I was blindly following anyone's load. This wasn't a load I found on a forum post. It was a safe starting load in a reputable reloading manual.

I also understand that I need to find a load that my specific rifle likes. That's over half the reason I bought this reloading equipment to begin with. Besides the ammo with 43 grains; I also loaded some with 44 grains and 45 grains. I was working my way up and then was going to get even more granular with my testing.

I quadrupled checked before I ever posted, the Lyman manual states IMR4895 not H4895 and I definitely understand there is a difference. Good catch though seeing that the starting load for H4895 states 43 grains.

With measuring our brass to the thousandth of an inch and measuring our powder to a 10th of a grain; it just seems like 5 whole grains different for a starting load between reloading data sources is absurd. It just surprised me and I was curious if that is common to see.

Apologies if my original post didn't have this same level of detail and made you guys have to assume that I hadn't already done certain things.

Thanks again.

 

[mountainman56]

As a rule of thumb, the older the manual, the more powder you can stuff in. What others have said about different testing methods are true but I think the biggest problem today is there are too many lawyers involved in loading data publication. They are so busy covering their butt with both hands that the information, especially max loads, becomes skewed. This is most noticeable in older cartridges, especially ones used in military rifles.

Don't get me wrong, I have a literal library of manuals but I use them mostly for powder selection and a starting load. I have yet to find a maximum load on a modern bot action that isn't to the right side of their published max.

JM2C

 

[PGJPJ]

That's a large difference in starting load, maybe more than most. This frustrates me as well.

QuickLoad data is also all over the place. The burn rate factor will likely be off, and requires calibration for most powders. Guys typically calibrate all sorts of things in QL, the guys on the Nosler forum talked about this quite a bit.

I think all this data just needs to be interpreted as a guide line. The best thing you have to go off of is chronograph measurements from you own rifle. If a book lists a load as "most accurate" try hitting that velocity, and it might very well be the most accurate. But the charge weight will likely not be the same. A chronograph will also let you know if you are stepping over on pressure.

That being said, I've used the Nosler manual for "most accurate load" and they did work very well. At least for hunting accuracy (1MOA or slightly less).