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October 20th, 2020

Out-of-Battery Blast Breaks Rifle and Bones in Shooter’s Hand

out of battery kaboom bohica 50 bmg ar15

As posted in the Calguns.net a few years back, there was a nasty out-of-battery firing incident involving a BOHICA Arms .510 DTC AR15 upper. The cause of the out-of-battery firing is not certain but it appears that the ammo was not sized properly and the firing pin may have been stuck in the extended position. As a result, the round went off before the bolt was closed with the lugs seated. In the process, the bolt handle broke off, as the bolt retracted violently, actually ending up outside the bolt raceway.

out of battery kaboom bohica 50 bmg ar15

The shooter was badly injured, with broken bones and ligament damage to his left hand and tissue damage to his right hand. The shooter was holding the rifle with his left hand near the front of the chamber where a gas vent was located. Gas and shrapnel existed the vent hole causing the severe injuries to the left hand.

From range reports, it appears that the shooter had been struggling to chamber previous rounds, and was having trouble closing the bolt. After talking with one of the rangemasters, a poster on AR15.com reported: “The guy was using new reloads that weren’t exactly fitting well into his chamber. [The shooter] was slamming the bolt handle with his palm trying to get the cases to lock in. The guy was also slamming the bolt forward full force from the rearmost position back and forth trying to ram the cases into chamber in an attempt to squeeze the rounds in so the bolt could close. Finally, on one of the attempts … the possibly stuck firing pin rams into the primer and explodes the round when he slams the bolt forward (zero lug engagement hence the KB) and shooter puts himself into a world of hurt.”

Lessons Learned — Don’t Try to Force Oversize Ammo into a Chamber
By all reports, the shooter’s ammo wasn’t fitting his chamber properly. In an effort to force the ammo into the chamber, he worked the bolt with excessive force. That MAY have caused the firing pin to extend or the hammer to fall without the trigger being pulled. One theory is that the trigger system may have been modified, allowing the hammer to fall from the force of slamming the bolt forward. Others have speculated that the firing pin may have failed to retract because the bolt handle was over-torqued — a safety issue listed in the BOHICA manual.

out of battery kaboom bohica 50 bmg ar15

Whatever caused the out-of-battery firing, it appears that improperly-sized ammo (or a poorly-cut chamber) was the root cause of the problems. If you go to a range and find your bolt does not close easily over the ammo — STOP SHOOTING — don’t try to force the issue. Disaster may result. To paraphrase Johnnie Cochran: “If the ammo doesn’t fit, it’s time to quit”.

Photos by Wildcard, originally posted on Calguns.net.

Permalink Gunsmithing, Tactical, Tech Tip No Comments »
September 14th, 2020

Over-Shooting the Berm Is All Too Easy — Five Degrees of Doom

Gun Angle long range

In our Shooters’ Forum, there was an discussion about a range that was threatened with closure because rifle over-shoots were hitting a farm building over two miles from the firing line. One reader was skeptical of this, asking “how’s that possible — were these guys aiming at the stars?” Actually, you may be surprised. It doesn’t take much up-angle on a rifle to have a bullet land miles down-range. That’s why it’s so important that hunters and target shooters always orient their barrels in a safe direction (and angle). Shooters may not realize how much a small tilt of the barrel (above horizontal) can alter a bullet’s trajectory.

How many degrees of muzzle elevation do you think it would take to hit a barn at 3000 yards? Ten Degrees? Twenty Degrees? Actually the answer is much less — for a typical hunting cartridge, five to seven degrees of up-angle on the rifle is enough to create a trajectory that will have your bullet impacting at 3000 yards — that’s 1.7 miles away!

Gun Angle long range

Five degrees isn’t much at all. Look at the diagram above. The angle actually displayed for the up-tilted rifle is a true 5.07 degrees (above horizontal). Using JBM Ballistics, we calculated 5.07° as the angle that would produce a 3000-yard impact with a 185gr .30-caliber bullet launched at 2850 fps MV. That would be a moderate “book load” for a .300 Win Mag deer rifle.

Here’s how we derived the angle value. Using Litz-derived BCs for a 185gr Berger Hunting VLD launched at 2850 fps, the drop at 3000 yards is 304.1 MOA (Minutes of Angle), assuming a 100-yard zero. This was calculated using a G7 BC with the JBM Ballistics Program. There are 60 MOA for each 1 degree of Angle. Thus, 304.1 MOA equals 5.068 degrees. So, that means that if you tilt up your muzzle just slightly over five degrees, your 185gr bullet (2850 fps MV) will impact 3000 yards down-range.

Figuring Trajectories with Different Bullets and MVs
If the bullet travels slower, or if you shoot a bullet with a lower BC, the angle elevation required for a 3000-yard impact goes up, but the principle is the same. Let’s say you have a 168gr HPBT MatchKing launched at 2750 fps MV from a .308 Winchester. (That’s a typical tactical load.) With a 100-yard zero, the total drop is 440.1 MOA, or 7.335 degrees. That’s more up-tilt than our example above, but seven degrees is still not that much, when you consider how a rifle might be handled during a negligent discharge.

Think about a hunter getting into position for a shot. If careless, he could easily touch off the trigger with a muzzle up-angle of 10 degrees or more. Even when shooting from the bench, there is the possibility of discharging a rifle before the gun is leveled, sending the shot over the berm and, potentially, thousands of yards down-range.

Hopefully this article has shown folks that a very small amount of barrel elevation can make a huge difference in your bullet’s trajectory, and where it eventually lands. Nobody wants to put holes in a distant neighbor’s house, or worse yet, have the shot cause injury. Let’s go back to our original example of a 185gr bullet with a MV of 2850 fps. According to JBM, this projectile will still be traveling 687 fps at 3000 yards, with 193.7 ft/lbs of retained energy at that distance. That’s more than enough energy to be deadly.

Permalink - Articles, Shooting Skills, Tech Tip 2 Comments »
January 18th, 2018

5 Degrees of Doom — The Danger of Over-Shooting the Berm

Gun Angle long range

In our Shooters’ Forum, there was an discussion about a range that was threatened with closure because rifle over-shoots were hitting a farm building over two miles from the firing line. One reader was skeptical of this, asking “how’s that possible — were these guys aiming at the stars?” Actually, you may be surprised. It doesn’t take much up-angle on a rifle to have a bullet land miles down-range. That’s why it’s so important that hunters and target shooters always orient their barrels in a safe direction (and angle). Shooters may not realize how much a small tilt of the barrel (above horizontal) can alter a bullet’s trajectory.

How many degrees of muzzle elevation do you think it would take to hit a barn at 3000 yards? Ten Degrees? Twenty Degrees? Actually the answer is much less — for a typical hunting cartridge, five to seven degrees of up-angle on the rifle is enough to create a trajectory that will have your bullet impacting at 3000 yards — that’s 1.7 miles away!

Gun Angle long range

Five degrees isn’t much at all. Look at the diagram above. The angle actually displayed for the up-tilted rifle is a true 5.07 degrees (above horizontal). Using JBM Ballistics, we calculated 5.07° as the angle that would produce a 3000-yard impact with a 185gr .30-caliber bullet launched at 2850 fps MV. That would be a moderate “book load” for a .300 Win Mag deer rifle.

Here’s how we derived the angle value. Using Litz-derived BCs for a 185gr Berger Hunting VLD launched at 2850 fps, the drop at 3000 yards is 304.1 MOA (Minutes of Angle), assuming a 100-yard zero. This was calculated using a G7 BC with the JBM Ballistics Program. There are 60 MOA for each 1 degree of Angle. Thus, 304.1 MOA equals 5.068 degrees. So, that means that if you tilt up your muzzle just slightly over five degrees, your 185gr bullet (2850 fps MV) will impact 3000 yards down-range.

Figuring Trajectories with Different Bullets and MVs
If the bullet travels slower, or if you shoot a bullet with a lower BC, the angle elevation required for a 3000-yard impact goes up, but the principle is the same. Let’s say you have a 168gr HPBT MatchKing launched at 2750 fps MV from a .308 Winchester. (That’s a typical tactical load.) With a 100-yard zero, the total drop is 440.1 MOA, or 7.335 degrees. That’s more up-tilt than our example above, but seven degrees is still not that much, when you consider how a rifle might be handled during a negligent discharge. Think about a hunter getting into position for a prone shot. If careless, he could easily touch off the trigger with a muzzle up-angle of 10 degrees or more. Even when shooting from the bench, there is the possibility of discharging a rifle before the gun is leveled, sending the shot over the berm and, potentially, thousands of yards down-range.

Hopefully this article has shown folks that a very small amount of barrel elevation can make a huge difference in your bullet’s trajectory, and where it eventually lands. Nobody wants to put holes in a distant neighbor’s house, or worse yet, have the shot cause injury. Let’s go back to our original example of a 185gr bullet with a MV of 2850 fps. According to JBM, this projectile will still be traveling 687 fps at 3000 yards, with 193.7 ft/lbs of retained energy at that distance. That’s more than enough energy to be deadly.

Permalink News 3 Comments »
February 14th, 2017

Blast from the Past — Video Shows Ricochet Danger

This an older video from the YouTube archives but we expect many readers have still not seen it yet. It definitely teaches an important lesson — never underestimate the destructive power of rifle-launched projectiles. What appears a “safe distance” from steel may actually be well within the danger zone.

YouTube Preview Image

In this video a rather ignorant (yet lucky) fellow demonstrates what NOT to do with a large-caliber rifle (a 50 BMG apparently). He shoots at a steel target about 70 yards away and a bullet fragment comes back directly at him. He was lucky enough that the ricochet just smacked his left ear muff. Another inch to the right and he could have lost his eye… or worse.

If you have ever done much action pistol shooting at close range on steel targets, you’ll know about the hazards of ricochets and bullet splashback. That’s why you should only shoot low-velocity rounds with soft lead or frangible bullets when shooting at relatively close range.

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