Starline 6.5 Creedmoor brass endurance testing- firing the same cases 15 times – rifleshooter.com

Starline 6.5 Creedmoor brass endurance testing- firing the same cases 15 times – rifleshooter.com



It is an expensive sport

Let’s face it, shooting precision rifles is an expensive sport.  The cost of a rifle, optics and ancillary equipment add up quick- and that’s well before you fire any rounds downrange.  Factory ammo can be cost prohibitive, so reloading becomes a necessary (and fun) endeavor.  The most expensive component of the metallic cartridge is typically the brass case, which fortunately, can be reused, allowing us to tell ourselves we are actually saving money.

The brass cartridge case is the foundation of centerfire ammunition.   If it isn’t made well your accuracy and precision will suffer.  For instance, if the quality of the metal is poor, you may end up with premature cracked necks, or loose primer pockets.  Brass quality can be measured in a number of different ways; consistency of case mass, case length, neck tension, concentricity, etc…  I wanted to take a look at how long a different brass cases would last over multiple firings as one method to inform our view of quality.

Reloading brass cartridge cases repeatedly introduces stress on the case.  Every time it expands during firing the material is work hardened, and, depending on the sizing method used, the case body may stretch a bit.  Set back the shoulder too much, or shoot it in too loose a chamber and you can end up with all minds of nasty problems including case head separation which can be dangerous.

I decided I’d test a random sample of five different brass cases with the same load over 15 firings.  I couldn’t think of a good name for this test, so I decided to refer to it as “brass endurance testing”.  In it, I’d randomly grab 5 cases from a box of factory brass, head to the range and construct the same load for 15 firings.  After each firing I’d use a set of Wilson Hand Dies (see file image below) to neck size the case, decap the primer and seat a new bullet.  The test would then be repeated until any one of the 5 cases showed a sign of potentially failing, at which point I would stop.  Note: for more information on reloading with hand dies, see Reloading 101: Introduction to Hand Dies

WARNING: The loads shown are for informational purposes only.  They are only safe in the rifle shown and may not be safe in yours.  Consult appropriate load manuals prior to developing your own handloads.  Rifleshooter.com and its authors, do not assume any responsibility, directly or indirectly for the safety of the readers attempting to follow any instructions or perform any of the tasks shown, or the use or misuse of any information contained herein, on this website.

A big caveat here, using a full length sizing die with a decapping pin would clearly accelerate the wear process on the case, as would a loose chamber.  So, depending on how your rifle was built and how you process your brass, your results may be very different from mine.

Picking a load

I was a bit torn about what load I should use.  Since I plan on testing a few different brands of cases, all of which might have slightly different characteristics, I wasn’t certain which to use.  If I selected one of my hotter H4350 142 SMK load for testing and encountered a heavier piece of brass with a smaller case volume I could run into some issues.  Further, I wanted to look at some actual targets when I was done, so some small groups on paper would be nice.  I happen to have quite a bit of 6.5 Creedmoor data that I gathers from a bunch of different guns with different lengths and makes of barrels.  I had used Hornady, Norma and Starline brass generating this data set and noticed most of the guns seemed to prefer to 142 SMK over 40.8 grains of H4350.  In Sierra’s load data, the H4350 loads start at 35.3 and go up too 41.9, so it isn’t the hottest load, however, it isn’t the softest either.

Readers have chimed in and sought for a more level playing field with my use of primers, so I moved away from my favorite Russian primer and went with standard CCI 200.

I loaded all of the rounds for this test at the range.  I used a Sinclair hand priming tool to seat the primers and a Harrell’s Culver Classic powder measure to drop charges.  All shooting was done prone, from a bipod with rear bag.   I used an excellent Rite in the Rain Storm Site Targets at 100 yards as a target.  Muzzle velocity was recorded with MagnetoSpeed Barrel Mounted Ballistic Chronograph.

Test gun

I’ve been using my custom Remington 700 a lot lately.  I know I typically switch around rifles more, however, I love this thing.  I built it with parts from Brownells, including:

I’ve been shooting the ESS chassis a lot lately and have grown quite fond of it! If you’ve been following my blog, you’ll notice the slick carbon fiber fore end and folding stock, I love this rifle! (Click here to learn more about the ESS)

Results

The brass shot better than expected, especially when you consider the cost of Starline brass when compared to some of it’s competitors.  These were random cases I just scooped out of a 500 round box.  No prep.  No hand picking.  The cases survived all 15 firings in good shape with no signs of cracking or impending failure.

Group size ranged from .311″ (.297 MOA) to .807″ (.771 MOA).  For all fifteen, 5-shot groups, average group size was .603″ (.576 MOA)!

Muzzle velocity ranged from 2,731 to 2,762 ft/sec with an average of 2,749 ft/sec.  Standard deviation for all fifteen muzzle velocities was a surprisingly low 9.24 ft/sec.

Number of firings v. group size

When I plotted the number of firings versus group size on a line graph, you’ll note an initial trend down for the first three firings, after that things don’t follow much of a trend.  Groups #3 and #11 were exceptionally small (below).

Number of firings v. muzzle velocity

When I plotted the number of firings versus the muzzle velocity, you’ll note a trend in increasing velocity.  I’d assume this was a function of the brass work hardening, however, that’s just a guess.

Closing

I’ve been shooting the Starline 6.5 Creedmoor brass for a little over two months and have been pretty impressed with it.  Take a look at the target above, I randomly picked up five cases and fired them 15 times with standard primers and thrown loads.  Average group size was just over .5 MOA, that’s over 15 5-shot groups.  That is really good and quite impressive.  It is worth noting that after the 6th firing the bolt required slightly more pressure to close and after the 14th firing required slightly more.   The primer pockets in all of the cases are still tight.

I’ll be repeating this same test with other brands of 6.5 Creedmoor brass utilizing the exact same load.  It will be interesting to see how the different makes of brass perform.

You can learn more about Starline Brass here, or purchase it at Brownells.





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