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August 15, 2018, 08:14 AM | #26 | ||
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Last edited by jmorris; August 15, 2018 at 08:21 AM. |
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August 15, 2018, 09:37 AM | #27 | |
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F. Guffey Reloaders have improperly seated cases with too much crimp. I understand to a reloader there is no correlation between bumping/moving the shoulder back and bulging the case at the case body/shoulder juncture; but the seating die does not have case body support, the full length sizing does have case body support: Meaning it is impossible to move the shoulder back when sizing a case it is possible to shorten the distance from the shoulder to the case head but the shoulder the reloaders starts with is not the same shoulder he finishes with. |
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August 15, 2018, 02:25 PM | #28 | |
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It seems like a good question to ask SAAMI.
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August 15, 2018, 02:49 PM | #29 |
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On reconsideration, I think part of the reason for the location is they are subtracting the effect of the maximum corner radius at each end of the chamber neck before locating the shoulder datum. The chamber's shoulder/neck corner radius is normally larger than the shoulder/body corner radius so a range of cases can fit without jamming. But this also means that when you pick a location on a fired case to measure, you have to pick a diameter that doesn't overlap the ends of those radii and expect to get a valid setback measurement off your resized case.
In the 223 Remington, for example, the shoulder is only certain to be flat between a diameter of 0.2768" to 0.3514". The exact middle of that range is where I would put it, but that is 0.3141". They chose 0.330". 0.315" would be the closest multiple of 0.005", and they didn't choose that. So I am thinking 0.330" was already used on something else and they decided to give it double duty. Again, it's worth asking them what the rationale is behind the choice.
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August 15, 2018, 08:34 PM | #30 | |
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August 16, 2018, 09:38 AM | #31 | |
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Speak where SAAMI speaks and be silent where SAAMI is silent: I am sure SAAMI was impressed with all of the qualifications listed by our members, I would not call SAAMI. I can not provoke most reloaders to push away from the keyboard to make room for a RCBS ROCK CHUCKER. They refuse to measure the amount of cam over for the ROCK CHUCKER. They insist the ROCK CHUCKER cams over because they heard it on the INTERNET. I have had 4 ROCK CHUCKERS, I am down to three; I do not own nor have I ever owned a ROCK CHUCKER that cammed over. I have at least 11 Herter presses, every one of my Herter presses cam over because they are cam over presses, my ROCK CHUCKERS are non cam over presses. Being a good shot does not make a member an expert at reloading. Read right and then up. F. Guffey |
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August 16, 2018, 10:00 AM | #32 | ||
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Again: The L.E. Wilson case gage has been with us for over 70 years, there is a chance reloaders could now be running L.E. Wilson 'BUT' before internet reloading the case gage has always been a case gage. The Wilson case gage is a datum based tool: Get a light, shine the light into the gage to aluminate the inside of the gage, for those that can push their way away from the keyboard can see the datum in the gage; It has a radius, I do not use the light. I use other methods but I have shop skills, I use a transfer method, when using the transfer method do not forget to lube the case. F. Guffey |
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August 17, 2018, 09:23 PM | #33 | |
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This is the only logical way to get a direct reading on a case that mirrors the chamber size from fireforming. They could choose a different hole diameter, I suppose, but then they have to calculate a different length for their cylindrical gauge. It's much simpler just to stick with the SAAMI numbers.
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August 18, 2018, 12:07 PM | #34 |
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