why is berger load data always so much lower than everyone else.

Tonight I was loading for a 338 Lapua with a 250 grain bullet and Hodgdon shows 98grains max for the 250 grain bullet while the berger manual shows only 90.0 for their 250 grain bullet. I find similar differences in nearly every caliber I look up data for.

I usually exceed the berger data but in this case 8 grains is a LOT of difference. Of course the Hodgdon data was for a 250 hornady bullet which could account for some of the difference. I loaded up to 96.6g and stopped. I have shot 95 before with no issues on the berger 250g OTM.

Do you usually look at 2-3 manuals and decide where to stop?

Sierra can also be counted on to be on the low end. ?

Because the data in the Berger manual is based on software simulation and not actual load test data ?

I am guessing that SOME of the loads had experience to back it up, but I too found huge differences compared to Hodgdon load data. Hornady handbook was also conservative, then you look at their published data for 6.5 Creedmoor - wow. Quite the contradiction.

Max loads for my rifles with my components are just that...for my rifles and components. I check 2-3 sources for a place to start.

Thank a lawyer for low max charge weights published by the manufacturers. They're working hard to prevent you from any litigation issues.

could be that the long slippery shape of the Bergers extends further into the case = less powder space = higher pressure?

I look at 2-3 manuals and 2-3 software programs for initial loading guidance. As I work my way up in powder charge weight, I let my rifles and the cartridge cases tell me if I'm approaching the real stop point for my particular rifle and load. Hard to eject cases; pancaked primers; hammered heads; as soon as any of these symptoms begin to present themselves, I back off a couple of tenths and declare that a "max load" for the rig. Then I load some more of them up at that reduced charge and test them again; one at a time, carefully examining each spent case for any pressure signs.

i usualy refer to one manual for a starting point load.
i will then load 1 round with a near max charge. i then load 1 more round with 1 gr increases.
when the bolt starts telling me to stop, i stop. i then back up about 1 gr and start my testing
backwards from there. i know the max charge with very few rounds which is what im looking for.
i do that with each powder. with wildcat cartridges there is no published data. this is your only
viable option. if it works for wildcats, why not factory chamberings?
its a good idea to shoot over your chronagraph while doing this.
a few years back i had a large 338 built. i was instructed to start at 132 gr h50bmg w/a 300gr.
shoot over the chronagraph 1 round at a time with 1 gr increases till i got to 32 to 3250 range.
then look around for accuracy with seating depth and small powder increases/decreases.
pretty much same scenario used by mikein.