November 19th, 2008

Muzzle Brakes — Bertalotto Tests Various Designs

Muzzle brakes are controversial. Some people swear by them, while others swear at them. Still, there’s no question that a good brake can reduce felt recoil up to 45%. And likewise, the best brakes, when installed properly, seem to have no negative effect on accuracy.

VAIS muzzle brake

Roy Bertalotto has done considerable experimentation with muzzle brakes, testing dozens of brake designs on his own rifles over the past few years. Roy’s article, Adventures with Muzzle Brakes, discusses various aspects of muzzle brake design and performance. Roy doesn’t claim that his testing is definitive, but his article is definitely worth a read. Here are some of Roy’s interesting findings:

Exit Hole Diameter
“Best accuracy and effectiveness of the brake was obtained with a hole .020″ over bullet diameter. If the exit hole is too small, such as +.005″ over bullet diameter, accuracy suffers. If the depth of the exit hole is too shallow, the metal around the hole will erode very quickly.”

Hole Placement
“The most effective braking was with a brake 1″ in diameter with a 3/4″ exit hole on each side, just in front of the muzzle. The bullet passes through a cone of 35 degrees before it exits the brake. (Like the tank example), Incredible reduction of recoil. But loud and ugly. Very easy to make since you don’t need a spin fixture or a dividing head.”

Bottom Gas Venting Helps Accuracy
“In my tests, not having holes all around the brake effects accuracy a bit. I believe it does something to the bullet by the air pushed ahead of the bullet creating unequal turbulence in the bullet path. I’ve tried a few brakes where I drilled only holes on the top, test fired, and then completed holes on the bottom and in every case, accuracy improved.” Below you see some spiral-ported brakes crafted by Clay Spencer.

VAIS muzzle brake

Brakes Work Best with High-Pressure Cartridges
“The higher the pressure of the particular round, the more effective the brake. I have over 20 rifles with brakes. The 220 Swift is the king of reduction. Followed very closely by the 25-06, 6mm Remington, any Weatherby small bore. With a proper brake and a hot handload under a 40 gr bullet, the Swift will move 1/2″ to the rear and 0 muzzle rise! Big boomers with low pressure like 45-70s and shot guns benefit the least.” [Editor's Note: Roy is judging effectiveness by the percentage of recoil reduction rather than absolute levels of recoil. Obviously if you start with a heavier-recoiling round, the absolute amount of recoil energy reduction is greater. Roy is really talking about efficiency--brakes are most efficient when used with high-pressure cartridges.]

Installation is Key to Accuracy
Roy’s findings are fascinating and suggest that further study of muzzle brakes is warranted. But we can all agree that precision installation of the brake is essential for accuracy. A poorly-installed, mis-aligned brake will degrade accuracy, that is well-known.

Harrell’s Precision has made tens of thousands of muzzle brakes, in many styles and port arrangements. The Harrell brothers offer some good advice for gunsmiths installing brakes: “Muzzle brakes aren’t magic, they reduce recoil by redirecting exiting gas. What’s important is that they are straight and the threads are perpendicular with the base. The only way to get the base and threads perpendicular is to thread, not tap, them on a lathe.”

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November 19th, 2008

SWFA.com Package Deal on Nikon Scope and Rangefinder

Here’s a sweet deal for a hunter looking for a 3-9 power scope and laser rangefinder for a low total cost. Currently, SWFA (Riflescopes.com) is offering a Package Deal. For just $349.95 total you get a Nikon 3-9×40 ProStaff BDC Scope, plus a Nikon ProStaff Laser 550 Rangefinder (with case). Nikon even kicks in a $50.00 Nikon ProGear Gift Card.

Nikon BDC Scope and Rangefinder

The 12.3″-long scope features low-profile windage and elevation knobs and weighs just 13.7 ounces. The ProStaff Rangefinder has a 6x21mm viewing lens, weighs just 6.3 ounces and is small enough to fit in a shirt pocket. The ProStaff 550 Rangefinder, by itself, sells for $185-$200 at other web vendors. This rangefinder has received generally quite positive reviews from Cabela’s customers. We suggest you read those reviews (in full) to decide whether the unit will meet your needs.

Bullet-Drop-Compensating Reticle
Nikon’s BDC reticle features a conventional medium plex crosshair augmented by four hollow circles placed below center on the verticle line. The small circles provide additional aiming points corresponding to Point of Impact at different distances. This way, the theory goes, a hunter can easily move from one distance to another without the need to click different elevations with his scope turrets.

Nikon BDC reticle

The standard Nikon BDC is designed to be used with most standard centerfire cartridges with typical bullet weights, providing aiming points out to 500 yards with a 100-yard sight-in. With magnum cartridges and typical bullet weights, the same scopes with BDC reticles offer aiming points out to 600 yards with a 200-yard sight-in.

Many of our Forum members have tried Nikon scopes with the BDC reticle. The general consensus was that the crosshairs are quite thick so this reticle is best suited for larger game out to 300 yards or so. At longer ranges, the reticle can obscure small targets such as prairie dogs. For deer and antelope, this can be a good reticle choice.

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November 19th, 2008

Hodgdon Equivalents for ADI Powder Codes

Many of the most popular powders sold under the Hodgdon brand in the USA (including Varget and H4350) are made by ADI Ltd. in Australia. Some load manuals list ADI data, but not Hodgdon data, or vice-versa, so we’ve compiled this list of equivalent powders. If you can’t find a recommended load for a particular Hodgdon powder in your caliber, download the latest ADI Smokeless Powders Handloaders Guide, a 2.8 megabyte Acrobat file.

Here’s a list of ADI to Hodgdon Powder equivalents:

AS30N=Clays
AP50N = (No Hodgdon)
AS50N = International
AP70N = Universal
AP100 = (No Hodgdon)
AR2205 = H4227
AR2207 = H4198
AR2219 = H322
Bench Mark1 = (No Hodgdon)
Bench Mark2 = BenchMark
AR2206 = (No Hodgdon)
AR2206H = H4895
AR2208 = Varget
AR2209 = H4350
AR2213 = (Discontinued)
AR2213SC = H4831
AR2217 = H1000
AR2225 = Retumbo
AR2218 = H50BMG

ADI smokeless power Hodgdon

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