Load manuals, then and now.

[str8shot426]

I have used my lyman 45th for quite a few years. It was published around 1970. Some load data from it matches current data and some does not. I use it mainly for data on cast boolits using powders no other manual lists.
I can't believe that they would change a powder enough to make this info dangerous. Never had a problem yet as I load from the bottom when trying new recipes.

For example. Lyman 45th 357 data with # 358156http://img.tapatalk.com/d/14/03/30/eraseqam.jpg

Lyman cast boolit handbook #4
http://img.tapatalk.com/d/14/03/30/ahesa4ez.jpg

One more reason to have several manuals and not to throw out your old ones.

[str8shot426]

http://img.tapatalk.com/d/14/03/30/yrypasyb.jpg

[smokesahoy]

I think it's mainly liability stuff but it explains why the old timers stress to start at the bottom and carefully work up while many new comers might drop the max in and roll with it. Some of those loads seem pretty toasty in the old book.

[WRideout]

I use the same manual, and found some loads there that are not found in current books: Example: 6.5 Japanese. Also, there are some cast boolit loads that use the slower rifle powders, which can be helpful at times.

Wayne

[44Vaquero]

Some powders have been reformulated over the years and variations do exist. More likely however, is newer data compiled by the powder manufactures using modern pressure testing equipment has yielded some surprises in the areas of peak pressure, duration etc.! This has resulted in what appears to be a more conservative compellation of reloading data.

Piezoelectric Transducers changed the game the level of accuracy is much higher than the older pressure testing methods.

Pre 70's manuals had some hot as hell loads in them! Use with caution! YMMV

[HollandNut]

I have the 45th as well as Hornady's 1967 manual , there are some differences no doubt