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November 30th, 2021

Wrong Cartridge in Chamber — What Can Happen

Ruptured Cartridge Case

If you don’t match your ammo to your chamber, bad things can happen, that’s for sure. A while back, Forum member BigBlack had an experience at the gun range that reminds us of the importance of safety when shooting. He encountered evidence that someone had fired the wrong cartridge in a 7mm WSM rifle. The problem is more common than you may think. This Editor has personally seen novices try to shoot 9mm ammo in 40 S&W pistols. BigBlack’s story is along those lines, though the results were much more dramatic. It’s too bad a knowledgeable shooter was not nearby to “intervene” before this fellow chambered the wrong ammo.

7mm-08 is Not the Same as a 7mm WSM
BigBlack writes: “I know this has probably been replayed a thousand times but I feel we can never be reminded enough about safety. This weekend at the range I found a ruptured case on the ground. My immediate thoughts were that it was a hot load, but the neck area was begging for me to take a closer look, so I did. I took home the exploded case and rummaged through my old cases until I found a close match. From my investigative work it appears someone shot a 7mm-08 in a 7mm WSM. Take a look. In the above photo I’ve put together a 7mm WSM case (top), the ruptured case (middle), and a 7mm-08 case (bottom).”

The photo reveals what probably happened to the 7mm-08 case. The shoulder moved forward to match the 7mm WSM profile. The sidewalls of the case expanded outward in the much larger 7mm WSM chamber until they lacked the strength to contain the charge, and then the case sides ruptured catastrophically. A blow-out of this kind can be very dangerous, as the expanding gasses may not be completely contained within the action.

Can’t Happen to You? Think Again.
This kind of mistake — chambering the wrong cartridge — can happen to any shooter who is distracted, who places even a single wrong round in an ammo box, or who has two types of ammo on the bench. One of our Forum members was testing two different rifles recently and he picked up the wrong cartridge from the bench. As a result, he fired a .30-06 round in a .300 Win Mag chamber, and the case blew out. Here is his story:

“I took two of my hunting rifles I have not used for over 25 years to the range yesterday to get new scopes on paper, a .30-06 and .300 Win Mag. I had four boxes of old Winchester factory ammo (two of each cartridge), which had near identical appearances. I accidentally chambered a .30-06 round in the Sako .300 Win Mag rifle. It sprayed powder on my face and cracked the stock at the pistol grip. If I had not been wearing safety glasses I might be blind right now.

Safety eyewear glasses
You should always wear protective eyewear, EVERY time you shoot.

“I feel lucky and am very thankful for being OK — other than my face looks funny right now. I am also grateful for learning a valuable lesson. I will never put two different cartridges on the bench at the same time again.”

READ More about this incident in our Shooters’ Forum.

Permalink - Articles, Bullets, Brass, Ammo, Tech Tip No Comments »
November 30th, 2021

Technology Insight: How Carbon-Wrapped Barrels Are Made

Proof Reseach carbon fiber barrel wrap aerospace composites

Montana-based PROOF Research has released a revealing video showcasing carbon fiber firearms technology and the company’s barrel-making process. Viewers will find the 8-minute film an intriguing introduction to composite barrel-making, which employs aerospace carbon fiber wrapped around a steel barrel core. The video showcases the high-tech machines used at PROOF’s production facilities.


This video shows how PROOF Research employs aerospace-grade, high-temperature composite materials to build match-grade carbon fiber-wrapped barrels.

Proof Reseach carbon fiber barrel wrap aerospace composites

Proof Reseach carbon fiber barrel wrap aerospace composites

Dr. David Curliss, General Manager of PROOF Research’s Advanced Composite Division, and former head of the U.S. Air Force High Temperature Composites Laboratory, explains how aerospace expertise helps in the development of PROOF’s firearms-related products: “We are able to provide premier materials for PROOF Research for firearms barrels applications as well as the aerospace market. We’re probably the only firearms technology company that has composite materials in orbit around the earth.”

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November 30th, 2021

Flash-Hole Fixer — How to Clear Flash-Hole Obstructions

Flash-hole reamer

Even with high-quality brass from Lapua, Peterson, Norma, Alpha and RWS, occasionally you may find one or two cases per box which have a small flake or obstruction in the flash-hole. This will appear like a thin crescent on one side of the flash hole (see photo). You should inspect ALL new brass before loading to identify any pieces with a partially-obstructed flash hole. It’s a good idea to remove any flake or thin crescent left as an artifact of the flash-hole forming process. Because the flash-hole itself is normally centered and of the correct diameter, it is not necessary to ream the flash-hole to a larger diameter. All you really need to do is remove the small obstruction(s). This can be done quickly with inexpensive tools.

Use a Small Pin Vise to Remove Flash-Hole Obstructions
Folks have asked if there is a tool that can remove obstructions from a Lapua small, BR-sized flash hole without opening the hole size. The Lapua PPC/BR flash hole is spec’d at 1.5mm, which works out to 0.059055″. Most of the PPC/BR flash-hole uniforming tools on the market use a 1/16″ bit which is nominally 0.0625″, but these often run oversize — up to 0.066″.

If you want to just clear out any obstructions in the flash hole, without increasing the flash hole diameter, you can use an inexpensive “pin vise” with an appropriate drill bit. For $0.99, eHobbyTools.com sells a 1.5mm drill bit, item 79186, that matches the Lapua flash hole exactly. Other vendors offer a #53 pin vise drill bit that measures .0595″ or .060″ (depending or source). An 0.0595″ bit is close enough. You can find pin vises and these small-diameter drill bits at hobby stores.

Pin vises Lapua Flash hole

For quite some time, Sinclair Int’l has sold a similar device for small (PPC and BR-size) flash holes. Like the 07-3081 unit for large flash holes, the 073000 Reamer for small flash holes works from the outside, so it can index off the primer pocket. It reams to .0625″, and also costs $29.99. The standard dimension for Lapua 220 Russian and 6mmBR flash holes is 1.5mm or .0590″. This tool will permit standard-size decapping rods with .0625″ tips to work without binding. However, note that both Forster and Redding normally supply .057″ decapping pins with their PPC and BR dies. So, it is NOT necessary to ream your Lapua BR/PPC flashholes, unless you prefer to do so for uniformity. It IS, however, a good idea to check BR/PPC flash holes for burrs before loading the first time.

AccurateShooter Sinclair Flash Hole Reamer

NOTE: If you purchase either the 073081 or 073000 Sinclair Flash Hole Reamer tools, we recommend you mic the cutter tip before you process a bunch of cases. Sometimes a tip comes through that is oversize. This will ream the flash holes larger than you may intend.

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