September 14th, 2015

Primer Pocket Rocket — Good Reason to Wear Safety Glasses

Primer Blown Gas defect winchester casehead

Our friend Grant Guess recently had a “close encounter” with a bad primer. An apparently defective primer caused part of the casehead on one of his rounds to blow out. This, in turn, allowed high pressure gas to vent through the damaged primer pocket. Take a good look, boys and girls. This is yet another very good reason to wear safety glasses. The cartridge was a 6.5-06, handloaded in necked-down Winchester-headstamp .270 Win brass. Grant reports:

“I had a blow through between the primer and the primer pocket today. The action was really smoking and I got a face full of gas. This was a reasonably light charge. Thank God for safety glasses.

I should also mention that it appears there is a 3/64 hole that is halfway between the primer and the primer pocket. Like it burned a small jet hole through both of them.”

Could this happen to you? It just might. On seeing this damaged case, one of Grant’s Facebook friends, Chris D., observed: “Search the internet, you will see a lot of these pin hole ‘in the corner’ failures. Obviously Winchester has some issues with the LR primers.”

Careful Examination Reveals Apparent Primer Defect
After this incident, Grant examined the damaged case: “I pinned the flash hole and it is not over-sized or under-sized. The primer clearly has an area where it had a defect. At [50,000 CUP], it doesn’t take much of a defect to cause issues. There was a slight bit of pucker-factor on the next shot….”

Primer Blown Gas defect winchester casehead

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September 14th, 2015

Tests Show Lapua .260 Remington Brass is Very Uniform

If you have a rifle chambered in .260 Remington, you may be wondering if the Lapua .260 Brass is worth the money compared to domestic-made brass. Well, the answer is “yes” if you demand consistent weight and dimensional uniformity (including neckwall thickness).

Mike Harpster of Dead Center Sports took the time to weigh and measure Lapua .260 Rem brass. His test show this brass to be extremely uniform. Weight variance was less than one (1) grain in a 20-case sample. And case neckwall thickness was very consistent.

Report by Mike Harpster: Lapua .260 Rem Brass Test Results (with Comparisons)
I pulled twenty (20) pieces randomly from one Lapua box to do some measurements. I weighed them on my Mettler-Toledo digital lab scale and here are the individual weights of each case. Remarkably, the Lapua brass had less than one grain total weight variance among all 20 cases!

While checking the Lapua brass I remembered I had just received some Winchester brand .308 brass, so I thought it would be interesting to do a comparison between the two brands. I again pulled 20 cases at random from a bag of 50 and repeated the same measurements. The results are shown in the right half of the table below.

Weight Variance Lapua .260 Rem Brass vs. Winchester-Brand .308 Win Brass

LAPUA .260 Rem Brass Winchester .308 Win Brass
Average: 172.20 grains
ES: 0.94 grains
SD: 0.259
Average: 158.49 grains
ES: 2.64 grains
SD: 0.678

Winchester Brass Further Inspection
The flash holes on the majority of the Winchester brass were not round or centered and they had large burrs inside. The neck wall thickness was pretty consistent, varying only .0015″ (.0125″ – .014″). As you can see in the photo (right) many of the Winchester cases were badly dented while the Lapua brass showed very few minor dents. The annealing on the necks of the Lapua brass was clearly evident while the Winchester showed no signs of being annealed. [Editor’s note: Winchester tumble-polishes its brass before shipping — so you would not notice annealing coloration if annealing had been done.]

Lapua Brass Further Inspection
With sample Lapua .260 Rem cases, I also measured the neck wall thickness in four places with calipers, not the most accurate method but I feel confident that the thickness did not vary more than .001″ over the 20 cases (.0145-.0155). The inside diameter of the neck measured .260 which would give .004 of neck tension out of the box. I visually checked the flash holes and I did not find any flakes of brass or burrs inside, the holes were round and centered.

Summary — This Lapua Brass is Impressive
I have never done these measurements on any other brass so I don’t know how they compare, but I am very impressed with the overall quality of the Lapua .260 brass. If they prove to hold up to the repeated firings I get from my Lapua 6BR brass I believe .260 shooters will be very happy.

Mike Harpster — Dead Center Sports
105 Sunrise Drive
Spring Mills, PA 16875
phone: 814-571-4655
www.deadcentersports.com

Permalink Bullets, Brass, Ammo, Gear Review 3 Comments »
September 14th, 2015

“Get Connected” with AccurateShooter.com on Facebook

AccurateShooter.com facebook friend social media forum

As more competitive shooting organizations (such as the U.S. F-TR Team) and manufacturers (such as Berger Bullets), turn to social media to distribute news and information, Facebook has become a much more valuable resource for shooters. Match reports (and photos) often appear first on Facebook, and many vendors post exclusive discount offers for their Facebook “friends”. AccurateShooter has an active Facebook page, and we are close to reaching 7000 “Likes”. Will you help us reach the 7000 mark?

UPDATE: Thanks Facebook Fans! We now have 6816 Likes (and counting!).

If you haven’t visited Facebook lately, check it out. You’ll find lots of valuable information being shared among serious shooters. And Accurateshooter.com also posts popular news items and updates on our AccurateShooter Facebook Page. You’ll find links to many other Facebook pages of interest, such as the USAMU Page, the Sinclair Int’l Page, the USA F-TR Team Page, the CMP Page, the Berger Bullets Page, and the Target Shooter Magazine page. Visit the page at www.facebook.com/AccurateShooter.

Facebook members can network with our page by simply clicking the “Like” (thumbs up) button near the top of the page. Facebook users who click the “Like” button can comment on our Facebook postings. In addition, if you visit our Facebook Page and click on the “MORE” button, you’ll find a Blog link with our latest Daily Bulletin items, complete with thumbnails and story summaries. You can also register with our Shooters’ Forum by clicking on the “Sign Up” button. There is no fee to join our Forum.

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