I have an old reloading Handbook (42nd edition Lyman) Question; Why are most of the loads listed for max velocities a lot higher, than the modern day relodaing manuels?
Example; Lyman 47th manual 358 winchester 250 gr bullet max is 41.5 gr. of IMR-3031
in the 42nd lyman manual a 250 gr is max at 46.0 grs. of IMR-3031.
I thought the new firearms where stronger than the old.

It has nothing to do with firearm construction. It has to do with lawyers and liability claims...

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http://stevespages.com/page8.htm

Also has to do with barrel and method used for tests. Current manuals will also have similar discrepancies.

I agree with riccardelli to a great extent. However, there are other reasons as well. For example, years back, many who wrote reloading manuals did not have access to pressure guns and ballistics labs. They published loads which were safe in the gunbs in which the loads were developed, but when they later tested some of these loads in pressure guns, they found the pressure-gun pressure levels to be higher than those thought permissible, so they cut the charges back. It is a fact that ammo which performs within permissible limits in factory barrels will OFTEN show higher pressures when tested in a pressure gun! In additon, SOME powders, bullets, and primers have changed in performance characteristics over the years, to the extent that loading data has had to be revised. A lot of this revision has been toward lower-powered loads. In some cases, this is actually what happened. In other cases, it is as riccardelli indicated, the reductions have been more due to a desire to avoid lawsuits than any other reason!! The problem is, HOW DO WE KNOW which of the foregoing factors are mostly responsible for a reduced powder charge recommendation in any given powder/bullet/primer/case combination? The answer is, WE DON'T!! This means we must be careful when we test any data found in ANY manual, old or new, by starting out at a reasonably reduced load level, and go up from there in small increments (if, indeed, we go up at all). In a rifle cartridge, for me, this increment is .5 grain, except for the small ones like the .22 Hornet or .218 Bee. In pistol cartridges, I use .1 grain increments. My persona rule is "STOP INCREASING POWDER CHARGE WHEN ACCURACY ACHIEVES AN ACCEPTABLE LEVEL", provided pressures have not gotten too high prior to this point!

Hey bluemule, Looking at the above responses, I agree with every one of them.

I think of the Component Manufactures Manuals as excellent "Guidelines" for where to start, but not cut in stone.

eldeguello's recommendation about starting low, seeing how the rifle performs and then deciding whether to go up or down with the Powder is what I do too. By "developing" your own Load, specific to your rifle and cartridge components, you should be able to get both good accuracy and SAFE Pressure levels.

Keep good records of all the Loads you try and it will become self-evident as you hit the right combination. Taking a Load straight from a Manual sometimes works but most of the time it can be improved on significantly.

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Good hunting and clean 1-shot kills, Hot Core

I had a similar problem with my 44 mag. I used a load from an old speer manual using Hodgon H110 powder which resulted in misfires jacket separations and a bullet lodged in the barrel. I wrote to the bullet , primer and powder manufacturers explaining the circumstances and the primer company said " a primer either goes off or not, not half off", the bullet company said "within specs", and the power company states all old data becomes obsolete with the publication of new data. So, reloader beware.

This may help:
Originally, many of the older manuals were constructed around loads developed by "reading" primers and measuring case-head expansion. When they began noticing disturbing pressure signs, the practice usually was to back off ten percent from the too-warm loads.

When some of the firms began using copper-crusher pressure-test barrels, their results alarmed them greatly. So, those manuals showed loads sharply lower than previously.

Finally, the industry decision was made to publish loads which did not exceed the industry standards for each cartridge as specified by SAAMI (Sporting Arms and Ammunition Manufacturers Institute). Now, barring screwups of various sorts, some manuals will show loads meeting these standards. Other manuals will show loads claiming to meet these standards but which have been reduced overall as a "fudge-factor" aimed at lowering imagined liability risks.

The result has been a collection of current manuals which are not in agreement with each other, and a highly frustrated bunch of American reloaders. It also has helped a lot with chronograph sales, since these are perhaps the only affordable way of assessing what reloads actually are doing.

Paladin

The old manuals were made by working up to where to bolt gets sticky and backing off 2 gr.

The new manuals are made by working up to where the bolt gets sticky and down to where the bullet gets stuck in the bore and taking the average of the two.