NEED HELP WITH MEASUREMENT

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74man

74man

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Just taking a consensus!! I have over 50 years in the Metal Trades and usually work to the 64th of an inch. I have a question fit for mainly Machinists. Here is my situation: I sent my Starrett Dial Caliper (1985) in for repair and Calibration and I got it back to day so I took some measurements of a 30-30 Win Case and I also compared it to two digital calipers I have and here is are the results:

Starrett Dial Caliper measured-- 2.034
Husky (Digital) (Home Depot) measured--2.028
Neiko (Digital) measured--2.024

Now with my 50 years experience at measuring to the 64th of an inch, I wouldn't worry about a few thousands but should I worry when it comes to measuring my trimmed cases? Would a few thousands matter in measuring case trim or Cartridge overall length? I don't reload for accuracy, I mainly load for SPRAY AND PRAY situations, so in my opinion they are close enough, what do the rest of you think, especially the machinists on this forum? With my eyes and age, I am very happy with a 3 inch or smaller group when I am at the range with what ever I am shooting being somewhere between handguns in calibers .22LR,32, 38 Spl.,.22 Mag, 40 S&W to a Ruger Blackhawk in 30 carbine. Rifles are 22LR, 22 Mag, 30 carbine, and 223Rem and 5.56. so I do reload the above calibers except the 22LR, SO SHOULD I BE WORRIED ABOUT A FEW THOUSANDS DIFFERENCE IN TOOLS??? Thanks to all who reply.
 
Uh, for 30-30, they need to be all the same for crimp consistency. A few thousands makes a lot of difference if it’s over max of 2.039. Set your trimmer to whatever, trim them every time you load them and don’t worry about the actual length is easy enough.

I trim mine to 2.028 just cause. A Lyman ezee trim or a Lyman universal.
 
74man said:
Just taking a consensus!! I have over 50 years in the Metal Trades and usually work to the 64th of an inch. I have a question fit for mainly Machinists. Here is my situation: I sent my Starrett Dial Caliper (1985) in for repair and Calibration and I got it back to day so I took some measurements of a 30-30 Win Case and I also compared it to two digital calipers I have and here is are the results:

Starrett Dial Caliper measured-- 2.034
Husky (Digital) (Home Depot) measured--2.028
Neiko (Digital) measured--2.024

Now with my 50 years experience at measuring to the 64th of an inch, I wouldn't worry about a few thousands but should I worry when it comes to measuring my trimmed cases? Would a few thousands matter in measuring case trim or Cartridge overall length? I don't reload for accuracy, I mainly load for SPRAY AND PRAY situations, so in my opinion they are close enough, what do the rest of you think, especially the machinists on this forum? With my eyes and age, I am very happy with a 3 inch or smaller group when I am at the range with what ever I am shooting being somewhere between handguns in calibers .22LR,32, 38 Spl.,.22 Mag, 40 S&W to a Ruger Blackhawk in 30 carbine. Rifles are 22LR, 22 Mag, 30 carbine, and 223Rem and 5.56. so I do reload the above calibers except the 22LR, SO SHOULD I BE WORRIED ABOUT A FEW THOUSANDS DIFFERENCE IN TOOLS??? Thanks to all who reply.
Click to expand...
I am not as experienced in reloading. But I have been a machinist for 23 years. I use a standard to check my tools. I have a short 1 inch for micrometers and a round 1 inch for checking calipers. I suggest you get your hands on a precision ball bearing. You can order 10 .625 chromed ball bearings for 6.72 on Amazon. What I recommend you do is check the known size. With calipers it is also good to check them at several points along the blade to see if they are closing parallel. This will help you figure out which one is correct. I’m inclined to believe starret dials over cheap digitals. I’m sure someone can answer the other part of your question.
 
Every set of calipers have their own feel. Like @Blkhrt13 says, order a set of 1” and 2” standard and check them on each caliper eyes shut until you have a feel for the set you want to use. Stick to one set, it’s all you need. Using one to check the others just guarantees you’ll never know which one is right. I’ll give you a hint: it’s not the calipers. As for how accurate you need to be, it matters about as much as being accurate with your powder. Plus or minus a half grain is either a nothing burger with fries or a trip to the emergency room. It just depends. Same with trimming consistency. Nothing or everything. Take your pick.
I will say this, being consistent matters way more than being accurate so if you can hit the same cut every time consistently, and you are at least close for your chambers, you’re golden.
 
I'll go against the grain and say that no, a few thousandths is rarely critical when measuring case length. Certainly, if case length falls within SAAMI spec, the very worst that will happen is slightly different crimp strength - and for a fellow who is content with 3 MOA, it won't even be noticed.

Beyond that, it seems that even then it would only be an issue if the OP is measuring with all three tools. If he uses just one, who cares if he thinks he's got 2.029 but he's actually got 2.027? As long as they are all the same, the actual number doesn't mean anything at all.
 
.38 Special said:
Beyond that, it seems that even then it would only be an issue if the OP is measuring with all three tools. If he uses just one, who cares if he thinks he's got 2.029 but he's actually got 2.027? As long as they are all the same, the actual number doesn't mean anything at all.
Click to expand...
Actually we agree. :)
Caveat: self loading rifles, especially tube magazine fed rifles need a tight hold on the bullet to prevent setback during the cycling operation. I don’t think I have to explain why.
 
It absolutely matters. And standards are the correct answers from scales to calipers. If you spent the money to have Sterrett fix a precision Guage barring any other data I would be inclined to trust that. To verify I recommend a precision ground Guage pin. They are cheap and work well.
 
Blkhrt13 said:
I am not as experienced in reloading. But I have been a machinist for 23 years. I use a standard to check my tools. I have a short 1 inch for micrometers and a round 1 inch for checking calipers. I suggest you get your hands on a precision ball bearing. You can order 10 .625 chromed ball bearings for 6.72 on Amazon. What I recommend you do is check the known size. With calipers it is also good to check them at several points along the blade to see if they are closing parallel. This will help you figure out which one is correct. I’m inclined to believe starret dials over cheap digitals. I’m sure someone can answer the other part of your question.
Click to expand...

To Quote Rush Limbaugh, "MEGA DITTOES".
Beleive in a 1" standard and the Starret and trim accordingly.
 
.010" between tools is a lot.

Edit add- .010" over maximum trim length on most bottle neck cartridges , may crimp the bullet in the chamber. This increases pressure to what may be a dangerous level. Kaboom.

Tne SAAMI drawing of the 30-30 seems to be more forgiving on the trim length?
 
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For the dimensions you can control (the dies control some of them), I don't think a spread difference of 0.010" between those three measurements is going to be significant. The needle width in the dial caliper is probably worth a couple of ten-thousandths when you read it against the dial marks.

I use a dial caliper I bought at an auto parts store (OEM). It's never given me a dimension that didn't work, and I load for 15 different cartridges and have been reloading for over ten years. dial caliper 2.jpg
 
Full sympathy; I'm lousy at precision measuring; before I had decent calipers, used a stored example of correct case or OAL, and compared it with a cheap set of calipers.
A previous poster noted, a lot of my problem is operator error.
Moon
 
bangswitch said:
For the dimensions you can control (the dies control some of them), I don't think a spread difference of 0.010"


The needle width in the dial caliper is probably worth a couple of ten-thousandths when you read it against the dial marks.
View attachment 1069147
Click to expand...
So .010 is a huge difference in head space, something I measure and control.
.0001 is spoken tenths.
 
AJC1 said:
It absolutely matters. And standards are the correct answers from scales to calipers. If you spent the money to have Sterrett fix a precision Guage barring any other data I would be inclined to trust that. To verify I recommend a precision ground Guage pin. They are cheap and work well.
Click to expand...
Yep, of those three, I would tend to believe the reconditioned Starrett.

No, .005 isn’t going to make or break you on trim length most of the time, but we can do better than that.

Get a 2” standard and see which one is the closest.
 
Blkhrt13 said:
been a machinist for 23 years. I use a standard to check my tools. I have a short 1 inch for micrometers and a round 1 inch for checking calipers.
Click to expand...
+1. Always good to verify reloading measuring tools with known standards.

Since caliper parts/surfaces can wear at different places, similar to using check weights in the same powder charge ranges, I like to verify my calipers around similar measuring ranges. Since measuring round bullets and case necks require "feel" to read consistent, I like to use pin gages to verify my calipers.

Vermont Gage plus/minus ZZ Class pin gages around $5 each - https://www.thehighroad.org/index.p...ks-for-digital-calibers.821135/#post-10545265
 
74man said:
Starrett Dial Caliper measured-- 2.034
Husky (Digital) (Home Depot) measured--2.028
Neiko (Digital) measured--2.024
Click to expand...
I wouldn’t have thought they’d vary that much. Did you do a one time measurement, or try it several times? On a 2” case, it’s easy to see a few thou difference in each measurement if you skew the jaws. 10 thou is a bit much, I’m not saying the digital is accurate or precise, but a check block would allow you to verify.
Regarding the delta readings, on a longer case for 30-30 I don’t sweat a few thou and even 10 thou I wouldn’t like but it probably wouldn’t be a problem, however on shorter cases like a 9mm that can make a larger difference. Good luck.
 
I think you need a gauge block and to spend a little time sorting out the calipers. I expect my calipers to be in the range of a couple of thousands error at the most.
 
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