Armory Sponsor
Posted: 1/30/2014 1:13:16 AM EDT
|
Just wondering how you guys measure your brass.
When checking it do you use your thumb against the roller and hold it tight as you can, and use that number? Or do you get it tight and then let it settle with your thumb off the roller? Only asking because this can equal a .003 diff on my el chepo calipers. Not sure which number to trust. |
|
Quoted:
Just wondering how you guys measure your brass. When checking it do you use your thumb against the roller and hold it tight as you can, and use that number? Or do you get it tight and then let it settle with your thumb off the roller? Only asking because this can equal a .003 diff on my el chepo calipers. Not sure which number to trust. I use mine as you describe in the second method. I think there is too much flexing to do it the first way. My calipers (1. Dan Kinneman's unamed one, Made in China and 2. Digital, Pittsburgh, Harbor Freight, Made in China) are probably as cheap as yours, though. |
|
With brass, I use the following method (I'm right handed)
I hold the brass between the jaws with my left thumb and pointer while my middle finger is on the right side of the jaw that moves (dial jaw) My right hand holds the bar/scale with my thumb on the roller. Using my right thumb and left middle finger, I move the dial jaw to the left until the brass is properly seated. Take note of measurement Release jaws about 0.25" and repeat. You could be getting a variation due to the brass not being perpendicular to its centerline axis while the jaws are closing. It could be that the case mouth is not parallel with the head (its crooked) and so isn't seating in the jaws properly. Try this. With nothing in the jaws, open them about 0.75" and close them, firmly. Do this 4 or 5 times. Does the dial always return to 0.000? If so, then its your technique and not the calipers. |
|
Close the jaws on the case with the wheel gently, then wiggle it to see if it shift. A lot of times it's not perfectly square with the jaws and a slight shift will make a few thousandths difference.
It doesn't take any more pressure than you need to make the jaws close completely. You should never force them. It's a precision instrument, not a pair of vice grips. |
|
Quoted: Close the jaws on the case with the wheel gently, then wiggle it to see if it shift. A lot of times it's not perfectly square with the jaws and a slight shift will make a few thousandths difference. It doesn't take any more pressure than you need to make the jaws close completely. You should never force them. It's a precision instrument, not a pair of vice grips. Sounds like the machinist who taught me how to use a dial caliper properly. He also insisted that I buy (in this order of preference) Starrett Mitutoyo Brown & Sharpe I do believe he would have had a stroke if I used a Harbor Freight, or similarly priced piece of crap. |
|
Quoted:
With brass, I use the following method (I'm right handed) I hold the brass between the jaws with my left thumb and pointer while my middle finger is on the right side of the jaw that moves (dial jaw) My right hand holds the bar/scale with my thumb on the roller. Using my right thumb and left middle finger, I move the dial jaw to the left until the brass is properly seated. Take note of measurement Release jaws about 0.25" and repeat. You could be getting a variation due to the brass not being perpendicular to its centerline axis while the jaws are closing. It could be that the case mouth is not parallel with the head (its crooked) and so isn't seating in the jaws properly. Try this. With nothing in the jaws, open them about 0.75" and close them, firmly. Do this 4 or 5 times. Does the dial always return to 0.000? If so, then its your technique and not the calipers. This pretty much is how I check the size. The extra detail that TerryC adds gives you the complete picture. |
|
Our family business is a machine shop. We only allow our machinists to use Starrett or B&S or Mitutoyo Absolute Digimatic. You close the wheel and use only enough pressure to hold the part AND NO MORE. .002 of flex is cheap calipers and/or rough hands.
We routinely machine to +/-.0005 tolerances, so it's important to measure correctly, Hell, if you're reloading in your garage and it's 95 degrees, you can get a different measurement than if it's winter and your garage is 50 degrees, due to thermal expansion. Quoted:
Sounds like the machinist who taught me how to use a dial caliper properly. He also insisted that I buy (in this order of preference) Starrett Mitutoyo Brown & Sharpe I do believe he would have had a stroke if I used a Harbor Freight, or similarly priced piece of crap. Quoted:
Quoted:
Close the jaws on the case with the wheel gently, then wiggle it to see if it shift. A lot of times it's not perfectly square with the jaws and a slight shift will make a few thousandths difference. It doesn't take any more pressure than you need to make the jaws close completely. You should never force them. It's a precision instrument, not a pair of vice grips. Sounds like the machinist who taught me how to use a dial caliper properly. He also insisted that I buy (in this order of preference) Starrett Mitutoyo Brown & Sharpe I do believe he would have had a stroke if I used a Harbor Freight, or similarly priced piece of crap. |
|
Quoted:
Close the jaws on the case with the wheel gently, then wiggle it to see if it shift. A lot of times it's not perfectly square with the jaws and a slight shift will make a few thousandths difference. It doesn't take any more pressure than you need to make the jaws close completely. You should never force them. It's a precision instrument, not a pair of vice grips. This. I will spin the case with my fingers when using the Hornady headcase and OAL bushings. Spinning it helps align it in the center of the bushings. |
|
You don't need to apply much pressure to get your measurements. I use cheap (GageShop.com) calipers which are identical to every other brand of Chinese calipers, just minus the branding. You'll have to buy two of them to get past their $20.00 minimum order or buy other items to complete your order.
I bought .2215, .2220", .2225" pin gages as well as .3060", .3065", .3070" pin gages to check neck tension in .223 and .30 caliber rifle brass after sizing. All sorts of pin gages come in handy for this purpose which helps identify cases with abnormal specs. |
|
Like so many things in reloading, how consistently you use the tool in question is the key. What I do is use the same light/firm motion every time. Always treat tools with respect and never force or use excessive pressure for the normal operations in reloading. Practice taking the same reading on something until you find your "sweet spot" and all the reading come out the same.
|
|
thanks for all the answers guys, I have been reloading for a few months now and have a decent handle on the subject but being that I am OCD with stuff like this its nice to have people like you all to help us newbs out.
I only reload .223/5.56 atm being as I do not shoot any of my other guns enough to be worth reloading for. I assume that will change soon as I leave NY though. So again, thank you guys a ton! |
Armory Sponsor