Why different starting loads in manuals?

[Bull Nutria]

when i started metallic reoading for 30.06 with 165 g jacketed Hornady BTSP CCI LR primer(200)in about 1976 i used

lymans 45th manual accuracy load 52.0g imr 4350 max 57g

lymans 49th starting load now 52.5g imr 4350 max 57

Speer 9th starting load 54g imr 4350 max 58.0g

Lee 2011 manual startring load 56.0g max 60.0g

well my question is why did Lymans change starting load and why the difference in starting loads between manuals?

Being the frugal person that I am and recoil sensitive I never tried any hotter loads than the 52 g imr "accuracy" load. this load has served me very well in my Rem model 760, I check my scope yesterday and shot my life" best" group at 100yds 3 shots that could literally be covered by a thin dime!!I have a witness!!

although lymans 49th says Imr 4064 is the current accuracy load, i am sticking with my old 52 IMR grains, light recoiling and very accurate in my gun rifle.

What say you reloading gurus??

Bull

 

[cfullgraf]

There are many reasons why loads vary from manual to manual. Different firearms or testing chambers, different powder lots, different bullet lots, different bullets, different primers, different cases, different weather conditions, different testers, different legal departments and a bunch more.

Over time, it seems charge levels have been getting lower. I believe in part due to improved testing techniques but I would not discount the affect of the lawyers.

Powders do change some over time as their manufacture moves from facility to facility and company to company.

From manual edition to edition, a company may not re-test a particular cartridge so the data seems to remain stabile. then they test it again and the data changes. Remember, there are lots of cartridges out there and it takes time to test them.

It is always best to use current data particularly with current manufacture powder.

 

[k4swb]

If all the manuals were exactly alike you wouldn't need but one.
They can't sell different books if they all are alike.

Don't get me wrong, all the books are good but just remember they just state where they started and finished with their test equipment and it really doesn't mean a lot as to what will actually work at the edges for your equipment.

 

[RandyP]

First, the most 'correct' answer to your question will come from dialing 800-225-9626 and asking the good folks at Lyman why their data changed. All of us on the internet can guess away, but Lyman should know for sure?

In general anyone creating unqiue data will use their own test protocols, which can change, and it is a reality that digital pressure test devices have greatly improved over the older crushed copper disk methods used before the digital age. So those companies using state-of-the-art testing machines will have 'better' data, or at least more accurate data.

 

[DesertFox]

Welcome to the reloading world! There's an extrapolation factor certainly. Detailed records along with careful observation are your friends.

 

[Hondo 60]

Why different starting loads in manuals?

Lawyers?

Or the technician from one company was a bit more or less daring than the tech from another company.

 

[gamestalker]

It has a lot to do with the modern methods used to determine pressures and a lot to do with lawyer's too!