Thread: Frustrating arvo at the range. Powder charges.

Originally Posted by dannyb

@grandpamac the Cortina method basically works on the theory you can tune any load by adjusting seating depth.
So basically do a charge weight ladder find you most consistent velocity node (lowest ES) then do a seating depth ladder to tune for accuracy.
I have never loaded for 223 so was waiting to see if anyone more experienced chimed in.
This method is championed by longrange pro shooter Eric Cortina and certainly he gets results, as have I but my experience is limited to 270win and above calibers up to 7mm rem mag.
Eric suggests not shooting your charge weight ladder at paper so as not to be suckered in to choosing a load that shoots a small group but has a large ES as this will likely be less accurate at long range due to the variation in velocity increasing exponentially the longer the range and therefore increasing group size.
Eric shoots PRS and bench and shoots some incredible groups out to 1000yards.
What I really like about his method is that he explains it in a way that made sense to me, I first started watching his videos when I was starting out in hand loading so a lot of the terminology was foreign to me Eric explains a lot in layman's terms which was easier for meto understand.
It's not for everyone and in reality is that level of precision even nessacary for a 223 with a max range for medium game well inside 500yards (my opinion no offense to anyone else) probably not. But it sure is fun and when you can understand what's happening and interpret what your group sizes are telling you it's quite fun.
Obviously there are loads of other variables that can be eliminated as mentioned above by @Friwi but again is it really needed for a 223, I wouldn't have thought so.

Thanks @dannyb,
I had a better look at the Audette method. It was as I suspected a series of single shots on paper at 300 yards or longer range to detect shots that were closer together in elevation. He was looking for harmonic convergance where the barrel vibrations compensated for vertical dispersion from the velocity differences from load to load. Crieghton Claudette was born in 1920 and died in 1992 and was for a time the Palma Match Captain so the method was probably developed by him and others in the 1950 to 1970 era. its strength is that it focusses on likely accuracy at range directly and its weakness was that it needed to be fired at longer range. The Palma Match is shot at 800, 900 and 1,000 yards or thereabouts so it is likely Crieghton tested at one of those ranges. Eric basically substitutes velocity for elevation which can be tested at short range. This is looking for flat spots in the progression of velocity together with smaller ES. Thanks danny this has got my mind going on this one and I think some tests are in order.
Regards Grandpamac.