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Primer pocket depth and uniforming

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: September/07/2012 at 09:12
Gil P. View Drop Down
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So there is no standard for the seating depth of primers just "below flush"?
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: September/07/2012 at 11:39
Alan Robertson View Drop Down
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Originally posted by Gil P. Gil P. wrote:

So there is no standard for the seating depth of primers just "below flush"?

Yes and no... a correctly seated primer is seated squarely in the pocket and not only bottomed out, but bottomed with a little more pressure so that the priming compound is slightly stressed, or crushed between anvil and cup, for consistent ignition.
The correct seating depth is typically achieved by "feel".
Some benchrest shooters have been known to use coax presses with dial depth indicators and force gauges to achieve consistent depth, although many (most?) precision shooters just seat primers by feel, with hand tools.

On another note, primer pocket uniforming should only be done once per case. Repeat use of the cutting tool only weakens the case and pocket cleaning after subsequent firing should be done with an appropriate tool.
Unless cases are slightly out of spec, with primer pockets either too tight or not deep enough- causing primers to be above the level of the case head-  pocket uniforming isn't really necessary and any effects of the uniforming would likely not be apparent except in 1/4 minute rifles fired at long distances, and any gained precision is questionable, even then. YMMV

Read some of the books by the great shooters, like Warren Page, and they scarcely mention the topic as pertaining to accuracy.
Most talk of primers and priming among precision shooters doesn't concern consistent seating, but focuses instead on using primers with sufficiently thick/hard cups to prevent piercing, which will produce flyers and in the case of semi- auto rifles, slam fires, with thin/high primers. This factor comes into play with cases using small rifle primers, as most LR primers are the same thickness.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: September/07/2012 at 12:15
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I once read that primers were supposed to be .004", or was that .04" below flush. I have been loading some unfired Winchester brass using the Lee hand primer to prime the brass. With many of them, if I can get the primers to seat .001" below flush I'm happy. I will be using a primer pocket uniformer on this brass, as well as a flash hole trimmer on this group of brass, but only on this group of brass, after all of the cases have been fire formed.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: September/07/2012 at 13:29
Gil P. View Drop Down
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With a uniformed primer pocket (pocket hole depth is .129), im seating the primers down to .006 closing the hand primer all the way down. I have tried to do it by feel, but is just isnt very consistent as sometimes they will be seated lower than .006 (.004-.008 by feel) maybe its just bad technique. Am I crushing primers by seating them to .006? All im worried about is crushing primers, i'll sacrifice consistency if I am crushing them by seating to .006.

Alan, ill make note to only uniform once.

Beltfed, it is very easy for me to seat the primers past .001 are you saying that it is difficult to do with your brass?


Edited by Gil P. - September/07/2012 at 13:54
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: September/07/2012 at 13:57
BeltFed View Drop Down
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Beltfed, it is very easy for me to seat the primers past .001 are you saying that it is difficult to do with your brass?
 
Yes, and this is one of the reasons I will be uniforming the primer pockets. I will only do it once.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: September/07/2012 at 17:26
Alan Robertson View Drop Down
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Originally posted by BeltFed BeltFed wrote:

I once read that primers were supposed to be .004", or was that .04" below flush. I have been loading some unfired Winchester brass using the Lee hand primer to prime the brass. With many of them, if I can get the primers to seat .001" below flush I'm happy. I will be using a primer pocket uniformer on this brass, as well as a flash hole trimmer on this group of brass, but only on this group of brass, after all of the cases have been fire formed.
That's what prompted me to start uniforming pockets in the first place; inconsistent/shallow seating depths on a brass lot.

I also have a K&M flash hole reamer, which reams the hole, deburrs and chamfers at the same time. Every now and then, there will be a case with a big chunk of punched- out brass which is too tough to remove (usually WW brass). I think that Lapua flash holes are drilled and not punched.

http://www.6mmbr.com/catalog/item/1433308/900728.htm
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/13/2016 at 08:57
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I Have deceided to go the extra steps in reloading by uniforming the primer pockets,flash holes,reaming and turning the necks on my reloads. I cannot find any info on the primer pocket depth. The tools all say they are set to the correct depth. The tools also have a set screw to adjust the depth incase they need adjusting but do not tell you the sammi spec depth. Thanks for any info to get me going in the right direction. JohnnyD
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