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blagg
Guest
Still looks like the shoulders are way longer on the last two, was that addressed? Like very long headspace.
D
Dennis Sorensen
Guest
Thinking more about this, usually high pressure with blown/flattened primers will be harder to extract as well...
Have you had any extraction indicator before primer blow?
Maybe a better bigger picture of the 4th case in the picture... I can't tell if that is expansion in that picture... if it is expansion then primers certainly aren't the problem.
Have you had any extraction indicator before primer blow?
Maybe a better bigger picture of the 4th case in the picture... I can't tell if that is expansion in that picture... if it is expansion then primers certainly aren't the problem.
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therifler
Guest
6.5 pressure
I am curious as to how you achieved your headspace ? How much neck tension you have on the case neck for loading ?
I am curious as to how you achieved your headspace ? How much neck tension you have on the case neck for loading ?
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rossneder
Guest
After some testing
GOOD NEWS
Simply changing to a lighter (sort of) VLD 107MK all pressure signs disappeared.
Even a compressed load of H4350 showed nothing which is to be expected. I came in from the shop to run a QL for RL17 with the 107s and am fairly confident that all is well.
I'll let you know and thanks for the help.
Ross
GOOD NEWS
Simply changing to a lighter (sort of) VLD 107MK all pressure signs disappeared.
Even a compressed load of H4350 showed nothing which is to be expected. I came in from the shop to run a QL for RL17 with the 107s and am fairly confident that all is well.
I'll let you know and thanks for the help.
Ross
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rossneder
Guest
OK, lets figure out what happened.
My theory is that the long shank of the 140 Amax jammed into the freebore/throat junction. Since it was pretty tight I suspect that the primer (Winchester SRP) was not able to unseat the bullet into the rifling before igniting the powder, hence the extreme high pressure with what should have been a normal load. I switched to CCI 450 which may have resolved the issue with just that extra push.
Since this is speculation, what do you think?
Best,
Ross
My theory is that the long shank of the 140 Amax jammed into the freebore/throat junction. Since it was pretty tight I suspect that the primer (Winchester SRP) was not able to unseat the bullet into the rifling before igniting the powder, hence the extreme high pressure with what should have been a normal load. I switched to CCI 450 which may have resolved the issue with just that extra push.
Since this is speculation, what do you think?
Best,
Ross
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Dennis Sorensen
Guest
Is the load data used actual suggested loads from a manual or calculated?
The toughest small rifle primer going is the Remington 7 & 1/2. It will handle pressures other wont.
The toughest small rifle primer going is the Remington 7 & 1/2. It will handle pressures other wont.
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nhkuehl
Guest
Primers
Now that you mention it, I recall reading an article(s) where there was concern about volume of powder to be ignited by a small primer in that case and the consenus was use magnum primers. Something like 'secondary ignition'(?).
I believe David Tubb designed the 6XC with a large primer because he felt loads over the 30-35 gr range didn't gain anything from a small rifle primer.
I have an action, barrel and the brass (6.5X47 Lapua) to make a 6X47 SM so I'll have to keep that in mind. nhk
Now that you mention it, I recall reading an article(s) where there was concern about volume of powder to be ignited by a small primer in that case and the consenus was use magnum primers. Something like 'secondary ignition'(?).
I believe David Tubb designed the 6XC with a large primer because he felt loads over the 30-35 gr range didn't gain anything from a small rifle primer.
I have an action, barrel and the brass (6.5X47 Lapua) to make a 6X47 SM so I'll have to keep that in mind. nhk
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rossneder
Guest
Dennis, this was initially a ladder test so the load varied from mild to hot. Although I never got past medium before over pressure.
Also I cut this chamber without an example of FN SPR chamber - end diagram. I decided to cut a small chamfered feed ramp, in retrospect I will not do that again or if truly necessary I'll make it considerably smaller.
Ross
Also I cut this chamber without an example of FN SPR chamber - end diagram. I decided to cut a small chamfered feed ramp, in retrospect I will not do that again or if truly necessary I'll make it considerably smaller.
Ross
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Larry Elliott
Guest
Even with a tight neck chamber a bullet should slip into the neck of a fired case without any pressure more than lining the bullet up straight with the neck and a light push on the meplat.
I'd bet that you've got case necks that are too thick and that the long bearing surface of the A-Max is making the problem worse. Short range BR chambers with "fitted" necks requiring no sizing were used with short shanked bullets which reduced the problems they might have otherwise had.
I'd bet that you've got case necks that are too thick and that the long bearing surface of the A-Max is making the problem worse. Short range BR chambers with "fitted" necks requiring no sizing were used with short shanked bullets which reduced the problems they might have otherwise had.
Jim Borden
New member
Ring too far forward
For what is worth:
That ring on the case indicates to me that there is too much exposed case body. I am truly wondering if there is high pressure or just too much case head exposed and flattened and blanked primers are from too much case headspace.
For what is worth:
That ring on the case indicates to me that there is too much exposed case body. I am truly wondering if there is high pressure or just too much case head exposed and flattened and blanked primers are from too much case headspace.
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nhkuehl
Guest
Neck thickness
"Old bald guy"..... I resemble that remark
I agree with you, that a bullet should slip in to the fired case. I shoot a .272 no-turn 6mm BR with unturned Lapua brass and the bullets slip in, but stop at the donut, which is no problem because I shoot 70-87 gr bullets that aren't seated through the donut.
"Old bald guy"..... I resemble that remark
I agree with you, that a bullet should slip in to the fired case. I shoot a .272 no-turn 6mm BR with unturned Lapua brass and the bullets slip in, but stop at the donut, which is no problem because I shoot 70-87 gr bullets that aren't seated through the donut.
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Dennis Sorensen
Guest
That's why I asked about a better picture... I didn't state it but I thought the 'ring' was awfully high on the case...
and a little headspace or head clearance will always flatten a primer...
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nhkuehl
Guest
Case headspace
Sorry if I'm being a pain. I don't know if you have a headspace gage (see pic*), but I think the .30 caliber comparator may sit on the radius at the shoulder and gives you a higher reading than the .350 headspace gage at the datum point, so you may have more headspace than you think(?).
The marks I was referring to on the necks were around the neck near the mouth and not the reflection along the length, is that what you meant too? nhk
*I know, I know; I catch grief about my cheap calipers.
Sorry if I'm being a pain. I don't know if you have a headspace gage (see pic*), but I think the .30 caliber comparator may sit on the radius at the shoulder and gives you a higher reading than the .350 headspace gage at the datum point, so you may have more headspace than you think(?).
The marks I was referring to on the necks were around the neck near the mouth and not the reflection along the length, is that what you meant too? nhk
*I know, I know; I catch grief about my cheap calipers.
Attachments
Bob Kingsbury
New member
I agree with Jim Borden, the line which appears to be a belt is to far
forward. The solid part of the case head should be well within the chamber.
To much chamfer with the old Sako ppc brass caused this same thing.
forward. The solid part of the case head should be well within the chamber.
To much chamfer with the old Sako ppc brass caused this same thing.