.338-06 AI - 07/04/08
To start with, I have always stayed out of Ackley Improved arguments because I never owned one before. Now I do have one. I kn0w for a fact, now,that there are a lot of people that do not understand what AI is about. For instance: �...if you load to the same pressure, you will get the same velocity...� My only comment is that you need to read Vol 1 of PO Ackley�s manual. He has covered that subject thoroughly.
What is more important is the *way* AI handles the pressure. It takes it off the bolt face and distributes it radially against the chamber wall. This works. The first sign of excess pressure will now be a leaking or blown primer. Pressure tests by POA indicate that this is about 63,500 psi. In addition to what POA says in Vol 1, read this discussion by David White:
http://shootersforum.com/showthread.htm?t=5813&page=2 Post #26
This difference really threw me when I started loading for this piece. there were never any of the usual signs. Finally, I got the P high enough. I didn�t know it until I was loading the cases again. There was very, very little resistance seating the primer. POA says that 1 grain below this point is Max for this combo. So I lowered the charge 1 gr and next time at the range, one of the primers fell out in the magazine. So I went back and started with new brass and here is the result:
This is a 300 yd group. 1 1/16 inches. The rifle I bought from Mud Bogger on the Campfire. It is a CZ 550 Minnesota, rebarreled by IT&D with a #5 Douglas CrMo @ 25 inches. The load is Fed brass, 4.35 cc H4350, F210GM, 250 SGK ~.025 off the lands. Shot off of the bed cover on the back of my truck.
Whether you think that fireforming brass is too much trouble, that is for you to decide. As for me, I am happy with what I�ve got...
What is more important is the *way* AI handles the pressure. It takes it off the bolt face and distributes it radially against the chamber wall. This works. The first sign of excess pressure will now be a leaking or blown primer. Pressure tests by POA indicate that this is about 63,500 psi. In addition to what POA says in Vol 1, read this discussion by David White:
http:/
This difference really threw me when I started loading for this piece. there were never any of the usual signs. Finally, I got the P high enough. I didn�t know it until I was loading the cases again. There was very, very little resistance seating the primer. POA says that 1 grain below this point is Max for this combo. So I lowered the charge 1 gr and next time at the range, one of the primers fell out in the magazine. So I went back and started with new brass and here is the result:
This is a 300 yd group. 1 1/16 inches. The rifle I bought from Mud Bogger on the Campfire. It is a CZ 550 Minnesota, rebarreled by IT&D with a #5 Douglas CrMo @ 25 inches. The load is Fed brass, 4.35 cc H4350, F210GM, 250 SGK ~.025 off the lands. Shot off of the bed cover on the back of my truck.
Whether you think that fireforming brass is too much trouble, that is for you to decide. As for me, I am happy with what I�ve got...