September 6th, 2015

Ballistics Tip: Understanding Bullet Stability (Twist Rate and MV)

Berger bullet SG MV twist rate stability Litz

Bryan Litz has produced an informative new video on the subject of bullet stability. The video explains how stability is related to spin rate (or RPM), and how RPM, in turn, is determined by barrel twist rate and velocity. For long-range shooting, it is important that a barrel have a fast-enough twist rate to stabilize the bullet over its entire trajectory.

Detailed Bullet Stability Article
To complement the above video, Bryan has authored a detailed article that explains the key concepts involved in bullet stabilization. Bryan explains: “Bullet stability can be quantified by the gyroscopic stability factor, SG. A bullet that is fired with inadequate spin will have an SG less than 1.0 and will tumble right out of the barrel. If you spin the bullet fast enough to achieve an SG of 1.5 or higher, it will fly point forward with accuracy and minimal drag.”


CLICK HERE to READ Full Bullet Stability Article by Bryan Litz

Berger bullet SG MV twist rate stability Litz

There is a “gray zone” of marginal stability. Bryan notes: “Bullets flying with SGs between 1.0 and 1.5 are marginally stabilized and will fly with some amount of pitching and yawing. This induces extra drag, and reduces the bullets’ effective BC. Bullets in this marginal stability condition can fly with good accuracy and precision, even though the BC is reduced. For short range applications, marginal stability isn’t really an issue. However, shooters who are interested in maximizing performance at long range will need to select a twist rate that will fully stabilize the bullet, and produce an SG of 1.5 or higher.”


Berger twist rate calculatorBerger Twist-Rate Stability Calculator
On the updated Berger Bullets website you’ll find a handy Twist-Rate Stability Calculator that predicts your gyroscopic stability factor (SG) based on mulitiple variables: velocity, bullet length, bullet weight, barrel twist rate, ambient temperature, and altitude. This very cool tool tells you if your chosen bullet will really stabilize in your barrel.

LIVE DEMO BELOW — Just enter values in the data boxes and click “Calculate SG”.

Top photo with bullet by Werner Mehl, www.kurzzeit.com, all rights reserved.
Permalink Bullets, Brass, Ammo, Tech Tip 6 Comments »
September 6th, 2015

Muzzle Brake Blast Pattern Comparison Test

Precision Rifle Blog Muzzle Brake Test Blast Powder

For a prone shooter, particularly on dusty, dirty or sandy ground, muzzle blast is a major bummer. Muzzle blast can be very disturbing — not just for the trigger-puller but for persons on either side of the gun as well. Some muzzle brakes send a huge shockwave back towards the shooter, and others send blast towards the ground, kicking dirt and debris into the prone shooter’s face. If there was a way to illustrate those factors — shockwave and debris — that might help shooters select one brake design over another.

Cal Zant at PrecisionRifleBlog.com applied a unique blend of creativity and resourcefulness to try to answer that question for 20+ muzzle brakes. Using high-speed photography and household products, he captured the blast pattern of 20+ different brake designs for easy side-by-side comparison. Can you figure out how Cal managed to show muzzle brake blasts so clearly? His “hi-viz” solution, revealed in the article, is very clever. See the eye-opening results for 20+ brakes, with illustrative photos, by visiting the Precision Rifle Blog Muzzle Brake Ground Signature Test Page.

Permalink Tactical, Tech Tip No Comments »
September 6th, 2015

Bleak Vision of Future Gun Control Becomes Reality in California

gun control los Angeles video pre-approval

A few years ago, some folks released a video that showed how gun control laws might operate in a fictional California of the future. The video shows how State Agency pre-authorization would have to be obtained before a handgun could be employed for self-defense in the home. Sound far-fetched? Well, it turns out that this satirical video was not that far from the truth. That disturbing vision of the future is coming to pass… at least in some parts of California.

The City of Los Angeles recently passed an municipal ordinance that would require handguns to be locked up (or otherwise disabled) when kept in the home. Modeled after a similar law in San Francisco, the Los Angeles ordinance makes it a misdemeanor to keep an unsecured handgun in a home. There are some exceptions to the locking rule (such as when the owner has the firearm in “close proxmity”), but this Los Angeles ordinance still imposes onerous burdens on citizens who might need a firearm to defend themselves in their own homes.

Under the new Los Angeles city ordinance, there is no “pre-authorization” requirement — at least not yet. But that could be the next step, as this video shows…

Think about it… how can you respond to an intruder if you have to call and ask for permission to access your own firearm. How that scenario might unfold is depicted in this video, a chilling preview of gun ownership in California. The video is a dramatization, but it shows what could happen in the Golden State in the not-too-distant future.

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