But it is also true that all rifles are individuals, and what proves to be a maximum load in one may be quite mild in another, and vice-versa!
A load which proves to be maximum in the rifle which was used to develop the loads published in any given manual is just that-maximum in that rifle. This does NOT relieve the handloader from testing worked-up loads in his/her own rifle to ensure that the loads listed as maximum are not OVER MAXIMUM in that person's rifle!! In addition, just because a load is labelled "MAXIMUM" in some manual does NOT mean it is MAX. in yours!!
For example, I have a .30/'06 underbarrel on my Heym O/U combination gun, and a Ruger No. 1 in .30/'06. Both these guns will handle a pretty warm 200-grain load without a hitch. But I cannot shoot this load in my .30/'06 TCR barrel-it will not stand it! Extraction is unacceptable, and primers are extruded into the firing pin hole. So this load is OVER MAX. in the TCR, and under MAX in the other two...... and so it goes!
I couldnt agree more!!! Given that all firearms are individual, it is up to the handloader to determine what is safe in any given firearm. I would highly suggest using the method outlined by Ken Waters in his book "Pet Loads".
Duck,
You may wanna play with your seating depth. I assume your rifle has been accurized? Barrel floated, action bedded, and trigger adjusted? Remember, listed maximun overall length may NOT be what your rifle wants. Most of my rifles like their bullets seated out more than SAAMI suggested overall length. Oddly, my .243 doesnt. It has a smallish chamber. And by the way, I would never setlle for a .243 that shoots more than .75" at 100 yards. It should do much better.