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MI, USA
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Posted: 7/10/2019 7:27:58 PM EDT
The specs on .308 indicate COAL should be 2.800.
I'm loading 175 gr SMK using a Lee press. I measure the length of every cartridge with digital calipers. My acceptance criteria is to be between 2.799 and 2.801. Roughly 1 in 10, I'll get 2.797. Got no idea why. I set those aside and re-do them later. What is your acceptance criteria +/- ?? |
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Posted: 7/10/2019 8:10:08 PM EDT
[#1]
I am far more interested in finding the distance my bullet travels to reach the lands and making sure the coal allows the cartridge to feed and fit the magazine I'm using. The measurements you are seeing could be variation in the bullets. It is more common to measure the distance from the case head to the bullet ogive, that is most important.
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Posted: 7/10/2019 8:14:18 PM EDT
[#2]
Get a comparator and measure base to ogive. It’s more consistent than COAL because you’re not having to deal with irregularities with the meplats.
The differences in the meplats can account for a lot of variability. The other things that may be causing you variance is neck tension, powder volume (if compressed loads) and residual case lube, but the meplats are 100% variable. Did I mention meplats? |
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Posted: 7/10/2019 8:46:34 PM EDT
[Last Edit: USSRangerSM]
[#3]
.010 off the ogive ( might play with it a little bit here and there) or whatever the mag length is
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Posted: 7/10/2019 8:58:51 PM EDT
[#4]
+/- 0.007"
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Posted: 7/10/2019 9:09:02 PM EDT
[#5]
Measure off the ogive OP, but you will likely still see more dimensional change than you think, I find this to be due to neck tension variances from case to case...I have my OAL's to under .0005" on my long range stuff...But it has been a lot of work getting there...
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Posted: 7/10/2019 10:09:26 PM EDT
[#6]
In my limited experience, once you get an average of 10 to load to spec, it's all variance in the bullet tip.
My 308 loads shoot great and COAL can easily vary +/- 4 thou. I don't yet have the equipment to measure to ogive, but I'd guess it's within a thou. They shoot great. |
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Posted: 7/10/2019 10:17:21 PM EDT
[#7]
Quote HistoryOriginally Posted By FritzTKatt:
In my limited experience, once you get an average of 10 to load to spec, it's all variance in the bullet tip. My 308 loads shoot great and COAL can easily vary +/- 4 thou. I don't yet have the equipment to measure to ogive, but I'd guess it's within a thou. They shoot great. Like you said there's variance in the bullet tip |
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MI, USA
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Posted: 7/11/2019 4:34:02 PM EDT
[#8]
Thanks for the input.
I had purchased the tools to measure the distance to the ogive, but I discovered my limiting factor is the magazine max length allowable: 2.800. My rifle chamber base to ogive (measured with 10 bullets, each measured 3 times) is average = 2.156" When my cartridge COAL is 2.800, the base to ogive of that cartridge is 2.140" So theoretically (I think), I have a jump of 0.016. I can't make cartridge any longer unless I start loading them by hand into the chamber. Not gonna do that. Thanks again for the input on measurement tolerance. |
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Posted: 7/11/2019 4:41:32 PM EDT
[#9]
That's all you can do with some guns is to measure to magazine length, but at least you have the right tool now for reloading and you'll get consistent measurements
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Posted: 7/11/2019 4:43:42 PM EDT
[#10]
Quote HistoryOriginally Posted By bigkahuna48026:
Thanks for the input. I had purchased the tools to measure the distance to the ogive, but I discovered my limiting factor is the magazine max length allowable: 2.800. My rifle chamber base to ogive (measured with 10 bullets, each measured 3 times) is average = 2.156" When my cartridge COAL is 2.800, the base to ogive of that cartridge is 2.140" So theoretically (I think), I have a jump of 0.016. I can't make cartridge any longer unless I start loading them by hand into the chamber. Not gonna do that. Thanks again for the input on measurement tolerance. You can see a "guide" round setting on the powder dispenser..  Attached File |
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USA
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Posted: 7/11/2019 5:30:12 PM EDT
[#11]
I seat them with my forward assist.
Just kidding, I’m a machinist by trade and +/-.005 seams excessive to me but it’s what I shoot for. |
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Posted: 7/11/2019 6:56:21 PM EDT
[#12]
In many firearms, COAL is determined by the internal dimensions of the magazine.
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Posted: 7/11/2019 9:41:59 PM EDT
[#13]
Quote HistoryOriginally Posted By bigkahuna48026:
Thanks for the input. I had purchased the tools to measure the distance to the ogive, but I discovered my limiting factor is the magazine max length allowable: 2.800. My rifle chamber base to ogive (measured with 10 bullets, each measured 3 times) is average = 2.156" When my cartridge COAL is 2.800, the base to ogive of that cartridge is 2.140" So theoretically (I think), I have a jump of 0.016. I can't make cartridge any longer unless I start loading them by hand into the chamber. Not gonna do that. Thanks again for the input on measurement tolerance. |
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MI, USA
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Posted: 7/11/2019 11:35:08 PM EDT
[#14]
Quote HistoryOriginally Posted By Rob01: What rifle and magazine? |
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USA
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Posted: 7/11/2019 11:48:19 PM EDT
[Last Edit: Cajun_Redneck]
[#15]
Just finished loading twenty five 75gr A-Max bullets. All within 2.389-2.391
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Posted: 7/12/2019 5:47:44 AM EDT
[#16]
Quote HistoryOriginally Posted By bigkahuna48026: Savage 10 with CDI bottom metal which accepts pmag magazine |
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Posted: 7/13/2019 3:15:05 PM EDT
[#17]
+/- .002"
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Posted: 7/13/2019 5:08:29 PM EDT
[#18]
Quote HistoryOriginally Posted By USSRangerSM:
Measure to the ogive and you'll see consistency with your measuring. Like you said there's variance in the bullet tip I have a forster mic seating die sitting on the bench, but I haven't loaded any lately (forgive my sins). So it's still in the box. I got it mostly for swapping between bullet weight/types, so I have the mic as a reference because it annoys the living hell out of me resetting a standard die. |
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Posted: 7/13/2019 5:53:08 PM EDT
[#19]
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Posted: 7/14/2019 12:58:06 PM EDT
[Last Edit: FritzTKatt]
[#20]
So one uses ogive measurements to ensure quality and then makes sure any bullet tip variations still allow for mag length/oal restrictions?
ETA: and also use the ogive measure to figure distance from lands... |
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FL, USA
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Posted: 7/14/2019 1:15:24 PM EDT
[#21]
Quote HistoryOriginally Posted By FritzTKatt:
So one uses ogive measurements to ensure quality and then makes sure any bullet tip variations still allow for mag length/oal restrictions? ETA: and also use the ogive measure to figure distance from lands... |
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Posted: 8/19/2019 11:10:49 PM EDT
[#22]
I learned long ago that cartridge overall length is a moving target. Since then I have measured all of my loads on the ogive. I load to +-.002 ideally. Anything that is outside those parameters goes int the practice or fouling box. I prefer my precision loads to be +-.001.
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FL, USA
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Posted: 8/20/2019 7:38:08 AM EDT
[#23]
So, my guess is you guys measure each cartridge at the ogive, then adjust the die on each one as it seats off the tip?
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FL, USA
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Posted: 8/20/2019 8:57:19 AM EDT
[Last Edit: Reorx]
[#24]
Quote HistoryOriginally Posted By mark5pt56:
So, my guess is you guys measure each cartridge at the ogive, then adjust the die on each one as it seats off the tip? |
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Posted: 8/20/2019 12:37:25 PM EDT
[#25]
Quote HistoryOriginally Posted By mark5pt56:
So, my guess is you guys measure each cartridge at the ogive, then adjust the die on each one as it seats off the tip? |
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FL, USA
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Posted: 8/20/2019 2:59:18 PM EDT
[Last Edit: mark5pt56]
[#26]
Thanks fella's. I have a RCBS standard set, do they have ogive stems?
edit-I saw the Hornady dies and they make stems. One I finish my supply of 175 smoke's, I will switch over to the ELDM and get dies at the same time. |
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Posted: 8/20/2019 11:29:44 PM EDT
[#27]
Quote HistoryOriginally Posted By mark5pt56:
Thanks fella's. I have a RCBS standard set, do they have ogive stems? edit-I saw the Hornady dies and they make stems. One I finish my supply of 175 smoke's, I will switch over to the ELDM and get dies at the same time. For my ground squirrel loads I don’t worry about all those procedures. I only do that for accuracy loads. If you want to load accuracy rounds invest in a Forester ultra micrometer seating die. It will save much time and effort. |
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Posted: 8/21/2019 9:09:03 AM EDT
[#28]
There is no need to do all that turning while seating with good dies. That is carried from years back and people's fears of runout. With a good die you can just seat a bullet in one step and it's accurate and good runout.
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