Keith,
you've quoted some pretty high velocities in a number of different cartridges which seem to exceed what is reported by others shooting the same cartridge. You have said several times that you aren't exceeding pressures. Are you using a strain guage or something similar to check pressure?
It may seem that I am getting much higher velocities than others, but I am sure that I am not talking apples to apples. For instance, a change in twist rate increases/decreases pressure (while many, many people say that it does not, I know from hands on exprerience that it does), barrel length, Chamber design is of major importance, and not the least the use of specific powder/brass/primer combo's.
Brass is the weak link in any cartridge, just watch for pressure signs. I have found that Federal and Rem brass are a little softer than Winchester, hence Win will take more pressure (I'm talkiing loads where you only have to neck size the cases). I won't shoot Norma brass because it is Soft.
Most of what you read is in factory rifles with huge sloppy chambers or in rifles. Comparing a factory rifle to a rifle with minimum spec chamber, custom barrel, is not comparing apples to apples, they are different animals. Of course I do shoot a lot of factory rifles.
I have also found that three groove barrels seem to be faster than their 5 and 6 groove when cut with the same reamer, using the same lot # of powder, etc.
My first real eye opener on differences in barrels was when I had a Rem 223 Sporter barrel opened up to a 22/250AI when it was a brand new barrel. I could not even come close to the velocities that I got with a Hart Stainless, same reamer was used. Next FUBAR was with a Rem 243 Sporter, that I had 1/2" cut off the breach end, then chambered with my 243 AI reamer. The factory barrel was slow compared to the Hart Stainless versions of the same type.
There is no solid evidence that I know of to leade one to think that the inside Bore Dia.(+*-.0002-.0003) height of lands, design of lands might make a monumental difference in speed and pressures, but I do know that these minute details may mean a lot.
When you read of some guy that gets fantastic accuracy with speed, it is a good idea to get him to elaborate on how he does what he does. I learned the techniques from gunsmiths and other shooters a long time ago, nothing new...we all learn from each other. All the guys that I shoot with that duplicate my results with their rifles would not dare post their results on the internet...too many guys that have no experience with wild cats that are closed minded and are experts because of what they have read...that is human nature.
The way that I and most people that work with wild cats judge safe pressure is when we can neck size the cases several times(or just bump the shoulder back .002 and get 12+ firings on a case) on your accuracy load. Our Remington's and custom actions don't blow up. I have some Rem 700's that are on their 5th and 8th barrels, with many on their 2nd and 3rd barrels.
If a guy were considering putting a custom wild cat on a flimsy action, break open of any kind, or a falling block, that person would have another entire set of pressure rules that would apply to him. I like strong actions for obvious reasons.
Hope this helps....
