Discussion in 'Reloading Forum (All Calibers)' started by apapig, Feb 14, 2018.
Which bushing should I use for 6.5 Creedmoor ?
I don't have a 6.5 creed , or I'd tell you the one I use . on other cases I use the one that sets about mid way on the shoulder .
C - Which should be .375"
Per SAAMI, chamber headspace is that point on the shoulder that is 0.400" in diameter and that point is 1.541" minimum and 1.551" maximum from the bolt face.
Maximum cartridge headspace is 1.538" to the same point.
Interesting. I wonder why Hornady prefers .375"?
If you're measuring to find a number that correlates to what you have on a chamber dimensional drawing, you need a bushing that's got an ID that matches the diameter of the case at the datum specified.
Hornady has both a 0.400" and a 0.375" bushing for their system.
If you're measuring from cases fired in your chamber and you want to set up your sizing die to move the shoulder back a given amount, either one will work. You don't need to match the datum-to-base dimension on a drawing, you just need to know when your sizing die's set to move the shoulder back as far as you want to, measured with whatever bushing you choose... 0.375", 0.400", 0.420" are all 'close enough'.
They don't, I have wondered why Hornady uses a radius in their datums, they get away with it because reloaders do not know the difference. If the datum has a radius it has to be corrected with a standard if the reloader is going to use SAAMI specs. I use case unfriendly datums, my datums have a very sharp edge. Once reloaders understood the datum was a rounds hole they hit the hardware stores purchasing bushings. They were stuck with 3/8" bushings because .400" and .410" were difficult to find, they can be made but difficult to verify.
I have always used the 0.400" as that datum is near the center of the shoulder.
You could use any bushing that fits past the neck but still hits the shoulder and calculate the difference in length for a 30° shoulder angle, but if you have the basic set then you should have both and don't need to calculate anything. This would be applicable if you want to load ammo that will chamber in any SAAMI spec chamber.
Nailed it! As long as you know that the shoulders of the cases fired in your chamber have fully expanded to the shoulder of the chamber, you're just making a comparison of that to your resized cases. It's just a number, as long as it's 0.00X" less.
Someone needs to explain to the OP if the datum/round hole is not the correct diameter the tool is turned into a comparator meaning the reloader must measure before and again after. If the reloader is measuring before firing and again after firing he is measuring the effect the chamber had on the case when fired. If he is measuring before sizing and again after sizing he is determining the length of the chamber from the datum/shoulder to the bolt face and sizing the case for clearance.
Many reloaders claim they move the shoulder back, at the same time they claim they are bumping the shoulder back and I ask; "How is that possible?" I can not move the shoulder back with a die that has full body support, if anything my shoulder does not move. I am able to shorten the case the case from the shoulder to the case head but if I managed that by moving the shoulder back the case would be 'rurant'.
And my cases do not have head space.
Calibrate your case headspace gauge with a chamber GO gauge then zero the case headspace measuring gauge. Then note the difference on your cases. Add or subtract the number relative to the GO gauge.
The diameter of the hole in the gauge and its edge shape doesn't matter. You are comparing a dimension on the case before and after firing. I've used half inch long nylon bushings with 3/8th inch ID on 30 caliber cases.
These labels on die lock rings let's you easily adjust them in different increments:
Print them on label paper, cut 'em out then stick 'em on lock rings.
Does that mean we call you special guffey?
You of all people, Bart B. you called SAAMI, SAANI said the case does not have head space, before that I said SAAMI does not use head space for the case, I told you the there is a case gage but the case gage is not a case head space gage, And there was L. Willis with his digital head space gage: At the time there were three reloaders that knew the difference between a dial indicator stand and a head space gage. L. Willis was selling a gage he called a digital head space gage, the fixture he was selling is called a dial indicator stand to, the educated, to others he was selling a comparator.
And then there is L.E. Wilson and their case gage, the tool has been around for over 70 years and for all those years it has been called a case gage by Wilson. Since the Internet reloaders have been calling the case gage a 'drop-in gage'. And now you want to call the case gage a head space gage for cases. Bart B. you have an infatuation with head space. When you called SAAMI did you tell them who you were?
If you would have been happy with the answer yes you should be as happy with the answer no. And then someone called RCBS to report me; They told RCBS I said the Rock Chucker is not a cam over press. They instructed the caller to have me call them. They were serious because they included a phone number, extension etc.
It is not fair because I am the only reloader with press instructions for the cam over press and the non cam over press.
Again, Bart B. the little degree wheel is not necessary, it never was. There were reloaders that converted degrees to thousandths, I can not fault the initiative but if the reloader wants thousandths why don't they verify the adjustment. I know, no one understand what that means but if they verify why don't the skip the shims and the degree wheel and the converting degrees to thousandths, I suggest the reloader skip the busy work and go straight to verifying. To verify measure the height of the die above the press.
If the reloader adjust/raises the die one additional turn the height of the die increases .071429", 1/4 turn equals .017857".
AGAIN, SAAMI SAID THEY DO.
Just like rimless bottleneck headspace gauges and chambers. They're well aware that the reloading industry and their customers agree that cases can have headspace. It's the distance from their back end to some point on their shoulder. There are several terms and conventions used in ammunition, SAAMI doesn't list all of them in their glossary.
It's a scale graduated in .002" for practical purposes, within 16 millionths of an inch, to change die position.
Again, no where in their case drawings do they use the symbol for head space for the case. Again, they only refer to head space in their drawings for the chamber. And again, the L.E. Wilson case gage has been with us for over 70 years and for all of those years Wilson has identified the gage as a case gage. They suggested the reloader use a straight edge, I added the feeler gage when measuring the length of the case from the datum to the case head. I also built a holder for a dial indicator when determining the length of the case from the datum to the case head. And now a reloader can purchases a tool for determining the length of the case from the datum to the cases head from Wilson.
Again, a reloader has only to verify and now you are telling me you make the adjustment without verifying?
Hornady has deviated from SAAMI standards before.
For decades, they said headspace was the distance from bolt face to case head with the case forward at the chamber stop. SAAMI calls that distance head clearance. A few folks still use that term incorrectly.
I have the case headspace changing and measuring tools, knowledge, skills, procedures, dexterity, confidence, faith and aptitude to do it precisely without verifying.
Others have all that stuff and do a better job than I do.
Separate names with a comma.