That is EXACTLY what happens with the 6.5 Gibbs case and why I designed the 6.5 Sherman which holds a little more than the Gibbs and has a MUCH better neck. This also happens with most of the A.I. cases based on the 'o6. That is why I always used .270 cases for my 6.5-06 A.I. and why I even use the 6.5x65 RWS or the .280 A.I. Nosler brass for my Sherman case........Rich
I used to be one of those guys that thought that the bigger the case behind the bullet the better. Then I moved back a few steps as all I was doing was blowing powder out the end of the barrel. But just didn't know exactly what was going on. While this was going on I watched buddies I shot with make a barrel maker rich! Then I read some stuff in P.S., and it got my wheels cranking again. I started to make CAD drawings of cases and figured the T.P. verses the throat. So after that on a whim I ran some thru a CAD program at work that allows you to factor in gas pressure and heat. That's where I figured that the T.P. had to be in the half of the neck closest to the shoulder if not the first third of the neck. Now then we get into the minds of Ferris and Lou Palmasono about case capacity and accuracey. I still don't grasp half of his thoughts. I'd like to have another eight hours of converstion with him, as I have questions.
But I have learned some things:
*too much powder to burn is as bad as not enough
*Keep the bullet away from the shoulders, and try to have the gas pressure comming off the shoulders to hit the bottom of the bullet even with the shoulders, or even slightly out from the shoulder. Gives a better seal in the case
*Long necks like beer bottles are better! They tend to guid the bullet into the throat better, creating better groups.
*too big a flash hole is as bad as no flash hole!
*sort cases by capacity in the end. The weight of a 1" cube of brass will vary a lot more than most of us ever thought
*I'm now a sonic cleaner convert!!!
*don't ever be afraid to think out of the box, but be conservative in your moves
*throw you case deburr tool away! I'll let you think on this one a bit
*when buying brass you usually get what you paid for
*fire form with cheap bullets unless you just doing a basic Ackley type chamber
*a great chamber is worthless if the neck, shoulders, and throat are not done as well (you'd be surprised how many great chambers have screwed up throats)
*lap that barrel! Then lap it again! Then relap the first three inches of the barrel after the neck. Always try to have the last three or four inches a couple tenths or so tighter (I learned that from Old Bill Calfee, so once again "Thanks Bill.")
*Just because the folks at Hogdons Powder sas it's a max load don't mean a thing! Some chambers will not take their max load, and some others want another half grain. But be carefull as chamber pressures tend to ramp up fast!!
*accuracey loads rarely correspond with max loads, and you gotta hit it first!
*Junk loading equipment often gives you some more junk. But expensive stuff isn't always best!
*learn to use gauges accurately. Learn to use micrometers in tenths accurately and consistently (I was lucky as my Dad was a toolmaker)
*the most unused word is "WHY?"
*the most overused phrase is "he does it this way."
*we all will eventually get our pinkies on a great shooting piece of iron, so how do we make it better? Be conservative here!
*learn the art of harmonics over the winter months, and then think hard on the subject
*learn about Stuart Otteson, and learn even more
I could do another twenty lines, but I won't
gary
