I am getting ready to work up some loads for my Dad and brother, is it better to load up a batch with consistent powder charges and different seating depth or try to find the most accurate powder charge then mess with the seating depth?

Well, look at it this way.

There's a max OAL you can load to. Can go shorter, but not longer. You can calculate this with tools, no shooting required.

There's a max powder charge. Don't want to exceed that. But you have to shoot to find this.

So..... I find the max OAL. Then I set the dies up to make sure the bullets are at least 0.020" off of the rifling, or if the mag is too short, as long as will feed reliably through the magazine (all with just dummy cartridges).

Now.... I use that length to work up powder charges. When I find the charge that works best, I might start making the OAL shorter, maybe 0.010" or 0.020" at a time, but keep the same powder charge. With that tiny change in OAL, there isn't any need to change the powder charge.

2 trips to the range, and I'm usually done. Your milage may vary....

Sounds like a plan to me! :D

I do it like MikeG states. Try to work with a dummy round to get a OAL I can live with before the powder starts to be thrown. Things can change in the process and there is a MIN OAL length to be concerned with because the deeper you seat that bullet the more you compress the powder. Lee's Modern Loading II gives MIN OAL but the only problem with that text is that you have to do some research to figure out who published the original data so that you know what bullet they where using. Here is a very real example...

I've started the pressure trace work for the 35 Rem and the first bullet I'm working with is the BTB 185-grain LFNGC. Of course, this is a lead bullet and a lever action rifle but it could be a jacketed bullet and any rifle with the same seating issues.

My bench work determined that a OAL of 2.192" would be the maximum that would work in the Marlin 336SC I'm using and that would leave the bullet .01" off the lands. For some reason in actual practice that didn't work. A couple of times, I thought the lever was closed but the trigger couldn't be pulled. Problem was the lever wasn't locked because the bullet/land contact was interfering. Cycling the lever a couple of times provided the necessary fit but that is something that you wouldn't want happening on a hunt.

So I'm going to seat the bullet .02" deeper as I now know that I have full land contact at my first OAL. The only bad part is that you are also reducing case capacity and increasing pressures. Take a look at the graphs from my RSI Shooting Lab software...

The data I'm using suggests a starting load of 35.0-grains for this bullet weight/powder choice working up to 39.0-grains. Notice that the first two images shows this range as uncompressed. Reseating this bullet pushes the load of 38.0-grains over 100% capacity and compresses the load. You would need to reevaluate your load work (work up to the 39.0-grains) again to see if there is any signs of excessive pressure.

35 REMINGTON LOADERS, PLEASE DO NOT USE THIS DATA FROM THE GRAPHS! IT IS NOT SAFE! Generating the data is part of the pressure work I'm doing on the 35 Remington and the software needs to generate these tables so I know what is safe or not. The shooting takes place with pressure trace equipment rigged to the barrel and each shot is evaluated to see if it is safe in MY FIREARM to continue to the next.

Good stuff guys, I haven't had any compression issues so far with any of the .243's I have loaded. I will use my stoney point gauge and probably start with the bullet .02 off, of course I may be stuck seating them a little farther off as I am loading up 58 gr v-maxes, they tend to not leave very much in the neck when seated out close to the rifling. I usually try to seat them at least 1 caliber width deep (which gives me nearly full neck contact on the .243).