I can't say one cartridge is anymore difficult to reload than the other. For me, the basic process of loading rifle cartridges is the same for 223 or 30-06.
I am a big fan of cartridge headspace gages. These gages are necessary to set up your sizing dies so you are either not oversizing or undersizing the case. The upper part of these cartridge headspace gages tell you the base to shoulder distance and after sizing, the base should not be below the low step or above the high step. This line drawing shows the basics:
This is the actual difference between Go and No Go on a 308 gage, it is only 0.006". You will never actually be able to set the cartridge headspace between these parameters without a gage. The typical sizing die instructions are to turn the die to the shell holder and add a quarter turn. This has never worked for me, and after I purchased gages, I found that all my cases sized by this method were out of spec.
The Wilson gage is cheaper than this Sheridan gage. The Wilson gage only measures shoulder to base distance, it does not provide a way to determine "fatness". Fatness is not really an issue for bolt rifles as the thing have massive cocking cams and you can beat the bolt down, or open, with a block of wood. However, if your ammunition is fired in a self loading rifle, then cartridge headspace and "fatness" are critical for function. There are lots of threads in this forum wherein the reloader had failures to extract because their case headspace was over length. This Sheridan gage is cut to a minimum SAAMI chamber size, so it will show either over length, underlength, and fat cases.
I full length resize and I set my case shoulders back about 0.003" from the chamber headspace, but, if I don't know chamber headspace, I will size the cartridge down the low step. I do not believe in neck sizing or partial neck sizing, these techniques will only cause chambering and extraction issues in time. I want ammunition that perfectly feeds and perfectly extracts.
After sizing I always trim the cases. It is my recollection that my .223 cases are trimmed to 1.750" and my 30-06 cases, well I don't remember the number right now. The primary purpose of trimming is to keep the case neck from being pinched in the throat. If this happens, you will blow primers. I have never found any effect for varying trim length on accuracy, maybe some benchrester has, but in a hand held weapon, nah. I trim, I deburr and bevel the case mouth.
I clean primer pockets but I can positively say, I have not found any accuracy difference between clean or dirty pockets. For my gas gun ammunition, I want primers below the case head so I actually ream the pockets in that stuff and clean out the pocket residue. I set all rifle primers by hand, that is I use a Lee Auto Prime and I inspect each and every round to ensure that the primer is below the case head.
IMR 4064 will shoot outstandingly in either cartridge but you are going to have to weigh each charge for best results. You will find that IMR 4064 will clog the powder funnel on occasion in the 223, the stuff is long grained and that is one of the issues with long grained powder. Long grained powders don't throw worth a hoot. If you have to crunch IMR 4064 in the 223 case, don't worry about it. I tried some IMR 4350 loads in the 308 Win, the case was full of the powder and I crunched the bullet down, and, I could see the bullet rising as the powder pushed back!. It never made any difference over my chronograph.
I do not have any loads for IMR 4064 in the 223, but with a 165 grain bullet in the 30-06, try 48.0 grains of IMR 4064. I tested 168 Match bullets with this load and it was accurate and not a hot load. Stay away from maximum loads.
The main benefit I see is as the post above says is the 30-06 is much bigger and therefore usually easier to work with. I would look in your manuals at your intended bullet weight with each caliber and look for a propellant that gives you a good velocity and reasonable pressure with a nearly full case. These seem to me to often be more stable in different temperatures so that is the way I try to choose my propellant.
