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Posted: 1/2/2019 10:22:56 PM EDT
[#1]
So your ES is 0.002" - that's pretty common... it's -0.003" ± 0.001". Did you measure them before they were fired??? I used to shoot for bumping the shoulder back 0.002 to 0.003 for my 308 bolt rifle... lost most of a batch of Federal cases by 12 firings due to ICS. I am now experimenting with bumping the shoulder less...
Free advice - if you like playing with finely adjusting headspace, you should own a Redding shell holder as well as a set of Redding Competition shell holders for 308 (size 1) in this case... Link |
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Posted: 1/2/2019 10:25:59 PM EDT
[#2]
Quote HistoryQuoted:
Did you measure them before they were fired??? |
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Posted: 1/2/2019 10:36:05 PM EDT
[#3]
Quote HistoryQuoted:
No, although I do have some left in a box that haven't been fired...I'll have to check. You might not have reached the actual chamber length yet... I would size cases to put the shoulder in the same place as the longest you have found... and then see what happens when you fire those - do a small batch. P.S.: In case you have not looked, headspace will get several (5-ish) thousandths larger if you only partially size the case by not going all the way to the bottom of the handle stroke... P.P.S.: DON'T be stingy with lube when trying to finely control headspace be sure your cases are well lubed. Don't over-do it but don't under-do it either... |
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Posted: 1/2/2019 10:51:00 PM EDT
[#4]
Free advice - if you like playing with finely adjusting headspace, you should own a Redding shell holder as well as a set of Redding Competition shell holders for 308 (size 1) in this case... Link |
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Posted: 1/2/2019 10:57:38 PM EDT
[#5]
Quote HistoryQuoted:
...and down the rabbit hole I continue to go! ;) |
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Posted: 1/3/2019 12:13:13 AM EDT
[#6]
I'm going to assume this is a gas gun? If so that's about what I run into with mine. I chock it up to the violent action of cycling.
If a bolt gun using the shell pates mentioned will make it very easy to control. One thing I try to do is use the same pressure when measuring and spin my brass 3x when measuring. I use Hornady gages. |
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Posted: 1/3/2019 4:15:45 AM EDT
[#7]
I see the same basic deal in my rifles..semi or bolt..has to do with the spring back of the brass, the chamber/case size /the dies/ and the process...takes several firings but they will close up some, but even on my hot stuff they will still come out slightly different in case length...I use a shoulder only die and set it to my longest case minus .002" then put a mark across the die and the press and loosen the die off a bit . I then measure each case as it goes thru, if its still long , I tighten the die a bit and resize till it's where I want it, then back the die off and go to the next one... Slow process, but not bad once you get the hang of it...
 Attached FileLongest case...  Attached FileSized...  Attached File Attached FileA half thou short..will shoot fine...  Attached File |
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Posted: 1/3/2019 1:53:48 PM EDT
[#8]
Quote HistoryQuoted:
I see the same basic deal in my rifles,...semi or bolt,... takes several firings but they will close up... After one firing, I measure a bunch and always assume the longest case is the chamber length. I size down 0.001" to 0.002" from that largest dimension. I check to ensure this size chambers easily. Re-measure the fired brass after each firing to ensure your assumptions are valid and adjust if needed. This approach has never failed me. |
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Posted: 1/3/2019 11:05:01 PM EDT
[#9]
I'm going to assume this is a gas gun? I measured a few more cases last night, just to see if there was any more variation. I tried some of the Prvi 140gr loaded ammo, and it all mic'd at 0.000 - 0.002" (based on the "0" reference point on the gauge). 1x fired, the brass was 0.000- 0.001". I found some Winchester nickel brass that is all 1x fired, but has been resized and currently loaded...it all measured -0.004 - 0.005". After firing, I got anywhere from -0.001 - 0.002 (majority was 0.000). 2x fired standard Winchester brass was from -0.001 - 0.002, so a spread of 0.003. |
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Posted: 1/4/2019 10:33:21 PM EDT
[#10]
Free advice - if you like playing with finely adjusting headspace, you should own a Redding shell holder as well as a set of Redding Competition shell holders for 308 (size 1) in this case... Link |
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Posted: 1/4/2019 11:20:10 PM EDT
[#11]
I have an adjustable die collar from PMA tools:
http://www.pmatool.com/pma-micro-die-adjuster-w-thumb-screw-upgrade/ 
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Posted: 1/4/2019 11:38:40 PM EDT
[#12]
Hmmm, more decisions. I guess the good thing with the adjustable die collar is it can be used with any die...
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Posted: 1/5/2019 1:15:23 AM EDT
[#13]
Quote HistoryQuoted: Getting ready to order the Redding comp shell holder set...is it one of those things I should definitely have? Good thing is, the same kit will work with .260, 7mm-08, and .308. |
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Posted: 1/5/2019 12:23:11 PM EDT
[#14]
Common. Until brass has been fired and neck sized at least 3 times with full pressure loads.
Or start with .010" between die and shell holder. Size. See if brass will chamber. Adjust die till brass chambers with slight hard bolt closure. May take a few firings. This will be the head to datum measurement to use. The Redding comp shell holder set will remove any slop from press flexing and linkage . The firing pin strike may see the shoulder back .006" on firing.( 223 in a Savage) |
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Posted: 1/13/2019 11:52:17 AM EDT
[#15]
I picked up a set of Redding competition shell holders, so now I am trying to figure out what else would greatly benefit setting up the cases. I picked up just over 100 pieces of Nosler brass, and I would like to make them last as loooong as possible.
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Posted: 1/13/2019 12:00:42 PM EDT
[#16]
Quote HistoryQuoted:
I picked up a set of Redding competition shell holders, so now I am trying to figure out what else would greatly benefit setting up the cases. I picked up just over 100 pieces of Nosler brass, and I would like to make them last as loooong as possible. In loading for .308, (so far) I have never retired a case because of a split neck and I have never annealed... FWIW... YMMV! P.S.: Why Nosler brass? |
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Posted: 1/13/2019 1:21:15 PM EDT
[#17]
Quoted:
I have an RCBS Precision Mic, and have been measuring the datum points on the shoulders ... Jason, you are measuring case length to a fixed datum. You are not measuring the "datum" on each case. There is a single datum you are using - it is the diameter of the opening in the gage. You are measuring the length of the case from the case head to the place at which the case diameter equals the datum diameter. This is commonly referred to as the "headspace of the case". |
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Posted: 1/13/2019 10:17:09 PM EDT
[#18]
P.S.: Why Nosler brass? I'm definitely looking at adding an annealing machine, but haven't decided on which one yet. I'd convinced myself to make one of these, but decided against it as there is no way to get consistent annealing doing it manually. I'll probably end up going with one with the dual drums, something that will anneal every case the exact same way. |
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Posted: 1/13/2019 10:19:46 PM EDT
[#19]
Minor Technical Correction -
Jason, you are case length to a fixed datum. You are not measuring the "datum" on each case. There is a single datum you are using - it is the diameter of the opening in the gage. You are measuring the length of the case from the case head to place at which the case diameter equals the datum diameter. This is commonly referred to as the "headspace of the case" |
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Posted: 1/14/2019 12:03:19 AM EDT
[#20]
I fixed a few cut and paste errors in my post. It might make sense now.
SAAMI specifies the datum diameter and range of acceptable case lengths in their spec for each cartridge type. Look through their "Cartridge and Chamber Drawings" for this info. Link to SAAMI web site |
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