F
Farmboy
Guest
I am working up a load for a 280 AI. Are the visual signs of approaching max pressure in a load as apparent or visible as non AI'd cartridges?
Wyatt
Wyatt
jackie schmidt
New member
Wyatt
The pressure signs that a lay person can identify are pretty universal, whether you are shooting a 30-30 or a 300 Ultra Mag.
Don't pay much attention to primer cratering. This is more times than not a problem with the firing pin fit and overall condition than it is pressure.
But, do pay attention to that outside radius of the primer shell. If that thing is completly flat, and darned near looks like it was painted onto the back of the case, then you are getting into the 60,000 psi area.
Of course, in a mechanically sound Rifle, a bolt that is difficult to open, or has a distinct "click" at the top, (with reasonably new cases), is always a sure sign that you are reaching the limit.
Keep in mind, Ackley Improved cases have very little body taper. A Rifle with inadequate primary extraction will probably produce a "click" even with loads that would be considered mid road.
As with anything that has to do with firearms, use a lot of common sense. Shoot over a good Chronograph. The Ackley Improved wheel was invented long ago, and there is a wealth of load data out there. Everybody pretty well knows what the chamberings are capable of. If you are shooting 200 fps faster than the reast of the planet, stop and think.
I like to pickup cases at the range and look at primers. It can be an eye opening experience.
Good Luck........jackie
The pressure signs that a lay person can identify are pretty universal, whether you are shooting a 30-30 or a 300 Ultra Mag.
Don't pay much attention to primer cratering. This is more times than not a problem with the firing pin fit and overall condition than it is pressure.
But, do pay attention to that outside radius of the primer shell. If that thing is completly flat, and darned near looks like it was painted onto the back of the case, then you are getting into the 60,000 psi area.
Of course, in a mechanically sound Rifle, a bolt that is difficult to open, or has a distinct "click" at the top, (with reasonably new cases), is always a sure sign that you are reaching the limit.
Keep in mind, Ackley Improved cases have very little body taper. A Rifle with inadequate primary extraction will probably produce a "click" even with loads that would be considered mid road.
As with anything that has to do with firearms, use a lot of common sense. Shoot over a good Chronograph. The Ackley Improved wheel was invented long ago, and there is a wealth of load data out there. Everybody pretty well knows what the chamberings are capable of. If you are shooting 200 fps faster than the reast of the planet, stop and think.
I like to pickup cases at the range and look at primers. It can be an eye opening experience.
Good Luck........jackie
F
Farmboy
Guest
thank you
Thank you for sharing your hard earned wisdom.
I had some concern that the lack of taper in the AI case may mask those normally observed signs.
Wyatt
Thank you for sharing your hard earned wisdom.
I had some concern that the lack of taper in the AI case may mask those normally observed signs.
Wyatt
jackie schmidt
New member
Wyatt
That is one of the little "unmentioned consequenses" of cases such as the A ckley Improved design.
This is not a new problem. I can remember years ago articles in magazines alluding to the exact same senario. Shooters who had converted over to the Ackley chamberings were plagued with extraction problems before the velocities that they wanted to gain were achieved.
The solution back then was to polish the chamber walls, so that the case would not tend to grip as much. But this, (in standard cases), can cause the bolt lift to be stiff at the beginning of the stroke. The Ackley'slackof body taper negated much of this, so it was all a big compromise.
I helped a friend build a 6.5x55 Ackley a few years ago, and we experienced the same problem. (It's a barrel block gun with a XP-100 hanging off). It has a generous barrel length, and shooting the big 6.5 140 grn Berger VLD at a flat 3000 fps should be no problem, with no other pressure signs, other than that annoying "click" at the top of the bolt stroke.
I since found that at one time, someone had "trued" that little XP-100, and after all of their efforts, had left the primary extraction lacking.
That is a good example when I mentioned the term "mechanically sound" in my first post. When looking for and identifying pressure signs, you have to take into account all factors........jackie
That is one of the little "unmentioned consequenses" of cases such as the A ckley Improved design.
This is not a new problem. I can remember years ago articles in magazines alluding to the exact same senario. Shooters who had converted over to the Ackley chamberings were plagued with extraction problems before the velocities that they wanted to gain were achieved.
The solution back then was to polish the chamber walls, so that the case would not tend to grip as much. But this, (in standard cases), can cause the bolt lift to be stiff at the beginning of the stroke. The Ackley'slackof body taper negated much of this, so it was all a big compromise.
I helped a friend build a 6.5x55 Ackley a few years ago, and we experienced the same problem. (It's a barrel block gun with a XP-100 hanging off). It has a generous barrel length, and shooting the big 6.5 140 grn Berger VLD at a flat 3000 fps should be no problem, with no other pressure signs, other than that annoying "click" at the top of the bolt stroke.
I since found that at one time, someone had "trued" that little XP-100, and after all of their efforts, had left the primary extraction lacking.
That is a good example when I mentioned the term "mechanically sound" in my first post. When looking for and identifying pressure signs, you have to take into account all factors........jackie
F
Farmboy
Guest
Alinwa
I know you have spent considerable time and $ in that effort. I would be very interested in some of what you can share.
Wyatt
I know you have spent considerable time and $ in that effort. I would be very interested in some of what you can share.
Wyatt