Which load data do you trust?
 

What is your "go-to" load data source . . . data from the powder company or bullet manufacturer?
Or do you use on-line data like Handloads.com?
I've noticed some pretty large (potentially dangerous) load differences between powder & bullet company. I just loaded my .308 using IMR 4064 using the Hodgdon data for a ladder shoot. Went from 40.7 to 45.2. I always load 5 foulers to get "on paper" and use the 'middle ground' of the load range. THESE WERE TOO HOT! BLEW THE PRIMER OUT OF ONE AND COULD HARDLY GET THE BOLT OPEN!
I'm loading Nosler Ballistic Tip Hunting in 180 gr. The Nosler data range is from 39.0 to 43.0. A significant difference. I'm using that next time!
I understand different barrels, lengths, primers, brass, etc. . . but Nosler's max is Hodgdon's middle ground!

I trust data that I work up in my rifles if looking for a max load, just to many variables to stick to the book, in another rifle or with a different bullet in your rifle, those loads may have been acceptable. with published data, start mid-level work up slow and watch for pressure signs, it you were getting heavy bolt lift, why the heck ya keep shooting?
RR

I was shooting other loads with 168 gr bullets. I did stop the 180's.

Yep,dig4gold,i've noticed the same thing,over the years! I,like most hand loaders,have more than one load data books. After a while you can just about have a sense of what is too hot! I trust the bullet makers books.

Every new load I work, I start from the very bottom and work up. You never know if the light load won't be the most accurate. I will sacrafice speed for accuratcy, every time. I also check the primer every time I go up in powder. I will check usually at least two sources before I start a new load. I have never blown up a rifle yet.........knock on wood, as soon as I see pressure on the primer, I stop. Hope this helps.

DanMorgan

Start in the middle and work up 1/2 grain at a time. Every rifle is an enigma. What works in one does not necessarily work in another. I have had rifles of the same caliber that would not accept loads that were perfect for its twin. They were way too hot. Size and trim brass .005 below max and begin your loading. I prefer loading 5 of each charge and spending the day at the range. Find your most accurate combination, and then go up or down with your charge 1/10th of a grain as needed. If it is a lesser charge, then be happy, because all of the velocity that you can get means nothing if you can't hit where you are aiming.

I once saw a fella
 

blow a gun apart at a range.

He mistakenly put about double the powder in the cartridge. He survived. Some people don't follow WRITTEN instructions. Those are the people I worry about.

I usually use the bullet company's data. Especially since I use Barnes X bullets and they have different properties than typical lead core bullets.

For plain Jane lead core bullets, I usually cross check a bunch of manuals and see where most loads are. I'll start around where most say is the middle load and tinker from there.

Since I use mostly Speer bullets I use their data for a starting point. They tend to be conservative so I work up till I start seeing pressure signs then adjust from there.

Good stuff all! And thanks.
I do have several load data books and on line sources.

The bullet mfg knows more about that bullet being pushed by said powder than the powder mfg knows about pushing said bullet.

That handy piece being known...I always look at both and veer to bullet side.

Simple answer: Pick up the phone.

I don't deviate much from my 'standby loads', so I can't remember the last time that I saw a discrepancy between published loads from the same timeframe (i.e. similarly aged editions of manuals), but the simplest answer is to just call the two and sift out the difference. As an shooter that runs "old cartridges in modern firearms", I end up seeing big gaps between published data from different sources (i.e. .45colt loads in Ruger revolvers, .45-70 loads for Marlins). Not all manuals have "ruger specific" or "marlin specific" sections, so I look at the data there, then make the calls to the bullet and powder manufacturer.

I'd be interested to hear what Hogdon had to say about the overpressure signs with their loads.

I use an average of the sources I have on hand. I think bullet companies want you to load light for liability reasons, and powder companies want you to load heavier so they can sell more powder. Just IMO. HD.