308 Case life span

mr renwick · July 20, 2010, 10:00 PM

How do you know when to stop using a 308 case? I picked up a bunch of 308 cases and don't know how many times they have been fired.

csmsss · July 20, 2010, 10:31 PM

Just like any other case - you have to inspect for the usual stuff - loose primer pockets, incipient cracks near the mouth or case head, bulging, etc. There's no magic number after which brass is no longer useful, but before which it is guaranteed not to fail.

mr renwick · July 21, 2010, 06:28 AM

Gotcha. I run on a tight budget so I have to make the most out of what I have. Thanks for the info.

dardascastbullets · July 21, 2010, 06:56 AM

Hi Mr. Renwick,

Yes, case life is determined by a few factors of which we can control. The load (primer, bullet, and powder) combination determines the life expectancy. And most importantly, the case headspace plays a major role as well. That is why it is so important to measure your chamber's headspace and setup your full length resizing die according to that dimension. This will significantly reduce the amount of unneccessary stretching of the case.

As the previous post mentioned, the primer pockets will begin to enlarge if the load is 'stout'. You will also notice a somewhat bright ring begin to form just above the case's base (approximately 1/2"). It is subtle at first but it will become very noticeable with repeat firings. Case head separation will occur eventually.

Now, to the matter at hand. You have some brass that you have picked up at the range. I will assume at this point that you have commercial brass that is all of the same headstamp. Look at the bases and pay particular attention to the primer pocket edge and the head itself. Are there black smudges around the perimeter of the primers between the primers' edge and the primer pocket? Do the heads have an imprint on them that looks like the face of a bolt ( that is to say, does it have circular bands with an imprint of an ejector pocket)? If the answer is yes to either of these two questions then the brass was left at the range for good reason - it is no longer useful. If you don't see these tell tale signs, then look at the case wall above the base and determine if there is the ring as I mentioned earlier. If there is, then the brass is useless. There is also the dental pick procedure that you can use to check for separation as well.

I trust that this will help you and good luck with your shooting the .308!

Dave R · July 21, 2010, 03:46 PM

It's been my experience that necks split far more often than case heads separate. I've had one case head separation in @ 12 yrs, but many split necks.

That said, case head failure is more traumatic in some cases. I generally limit brass I know to 6-8 firings. Trim once after 3-4 firings

wogpotter · July 21, 2010, 04:02 PM

It depends on the action & load density a bit as well. A self loader 2, maybe 3 loads is all you'll get before the case gets too beat up to reload, especially if the loads are near maximum for gas operation to be reliable. Bolt guns with light loads you may get 12~15!

As a lot of .308 cases are used in semi-autos, or even machine guns, I'll throw this one more test in.

Take a paperlip, make it into a single rod by unbending enough to reach all the way down inside the case to the back, leave the rest folded as a handle.
Now make a short bend on the end at a 90 degree outside angle.
Run this "probe tip" along the inside of the case wall from base to shoulder at several points around the circumference.
If there is a "catch" at an internally thinned wall then the case is toast as it has stretched & will soon separate.:barf:

July 20, 2010, 10:00 PM	#1
mr renwick Junior member Join Date: January 10, 2008 Posts: 42	308 Case life span How do you know when to stop using a 308 case? I picked up a bunch of 308 cases and don't know how many times they have been fired.

July 21, 2010, 06:56 AM	#4
dardascastbullets Senior Member Join Date: July 20, 2008 Location: Essexville, MI Posts: 164	Hi Mr. Renwick, Yes, case life is determined by a few factors of which we can control. The load (primer, bullet, and powder) combination determines the life expectancy. And most importantly, the case headspace plays a major role as well. That is why it is so important to measure your chamber's headspace and setup your full length resizing die according to that dimension. This will significantly reduce the amount of unneccessary stretching of the case. As the previous post mentioned, the primer pockets will begin to enlarge if the load is 'stout'. You will also notice a somewhat bright ring begin to form just above the case's base (approximately 1/2"). It is subtle at first but it will become very noticeable with repeat firings. Case head separation will occur eventually. Now, to the matter at hand. You have some brass that you have picked up at the range. I will assume at this point that you have commercial brass that is all of the same headstamp. Look at the bases and pay particular attention to the primer pocket edge and the head itself. Are there black smudges around the perimeter of the primers between the primers' edge and the primer pocket? Do the heads have an imprint on them that looks like the face of a bolt ( that is to say, does it have circular bands with an imprint of an ejector pocket)? If the answer is yes to either of these two questions then the brass was left at the range for good reason - it is no longer useful. If you don't see these tell tale signs, then look at the case wall above the base and determine if there is the ring as I mentioned earlier. If there is, then the brass is useless. There is also the dental pick procedure that you can use to check for separation as well. I trust that this will help you and good luck with your shooting the .308! __________________ Matt Dardas

July 21, 2010, 03:46 PM	#5
Dave R Senior Member Join Date: January 7, 2000 Location: Idaho Posts: 6,073	It's been my experience that necks split far more often than case heads separate. I've had one case head separation in @ 12 yrs, but many split necks. That said, case head failure is more traumatic in some cases. I generally limit brass I know to 6-8 firings. Trim once after 3-4 firings __________________ I am Pro-Rights (on gun issues). Last edited by Dave R; July 21, 2010 at 03:50 PM. Reason: Clarifying

July 20, 2010, 10:31 PM	#2
csmsss Senior Member Join Date: October 24, 2008 Location: Orange, TX Posts: 3,078	Just like any other case - you have to inspect for the usual stuff - loose primer pockets, incipient cracks near the mouth or case head, bulging, etc. There's no magic number after which brass is no longer useful, but before which it is guaranteed not to fail.

July 21, 2010, 06:28 AM	#3
mr renwick Junior member Join Date: January 10, 2008 Posts: 42	Gotcha. I run on a tight budget so I have to make the most out of what I have. Thanks for the info.

July 21, 2010, 04:02 PM	#6
wogpotter Senior Member Join Date: September 27, 2004 Posts: 4,811	It depends on the action & load density a bit as well. A self loader 2, maybe 3 loads is all you'll get before the case gets too beat up to reload, especially if the loads are near maximum for gas operation to be reliable. Bolt guns with light loads you may get 12~15! As a lot of .308 cases are used in semi-autos, or even machine guns, I'll throw this one more test in. Take a paperlip, make it into a single rod by unbending enough to reach all the way down inside the case to the back, leave the rest folded as a handle. Now make a short bend on the end at a 90 degree outside angle. Run this "probe tip" along the inside of the case wall from base to shoulder at several points around the circumference. If there is a "catch" at an internally thinned wall then the case is toast as it has stretched & will soon separate.:barf: