August 5th, 2018

Cartridge “Efficiency” — Factors to Consider from the USAMU

USAMU Handloading Guide Facebook cartridge efficiency

Efficient cartridges make excellent use of their available powder and case/bore capacity. They yield good ballistic performance with relatively little recoil and throat erosion.

USAMU Handloading Guide Facebook cartridge efficiency

Cartridge Efficiency: A Primer (pun intended!) by USAMU Staff

Each week, the U.S. Army Marksmanship Unit (USAMU) publishes a reloading article on its Facebook Page. In this week’s article, the USAMU discusses cartridge case efficiency and its benefits. While this is oriented primarily toward NRA High Power Rifle and Long Range (1000-yard) competition, these factors also apply to medium/big game hunters. Assuming one’s rifle and ammunition are accurate, key considerations include ballistic performance (i.e., resistance to wind effects, plus trajectory), recoil, and throat erosion/barrel life.

Efficient cartridges make excellent use of their available powder and case/bore capacity. They yield good ballistic performance with relatively little recoil and throat erosion. A classic example in the author’s experience involved a featherweight 7x57mm hunting/silhouette rifle. When loaded to modern-rifle pressures, just 43-44 grains of powder pushed a 139gr bullet at 2900 fps from its 22” barrel. Recoil in this light rifle was mild; it was very easy to shoot well, and its performance was superb.

An acquaintance chose a “do everything” 7mm Remington Magnum for use on medium game at short ranges. A larger, heavier rifle, it used ~65 grains of powder to achieve ~3200 fps with similar bullets — from its 26″ barrel. Recoil was higher, and he was sensitive to it, which hampered his shooting ability.

Similarly efficient calibers include the 6mm BR [Norma], and others. Today’s highly-efficient calibers, such as 6mm BR and a host of newer developments might use 28-30 grains of powder to launch a 105-107gr match bullet at speeds approaching the .243 Winchester. The .243 Win needs 40-45 grain charges at the same velocity.

Champion-level Long Range shooters need every ballistic edge feasible. They compete at a level where 1″ more or less drift in a wind change could make the difference between winning and losing. Shooters recognized this early on — the then-new .300 H&H Magnum quickly supplanted the .30-06 at the Wimbledon winner’s circle in the early days.

The .300 Winchester Magnum became popular, but its 190-220gr bullets had their work cut out for them once the 6.5-284 and its streamlined 140-142gr bullets arrived on the scene. The 6.5-284 gives superb accuracy and wind performance with about half the recoil of the big .30 magnums – albeit it is a known barrel-burner.

Currently, the 7mm Remington Short Action Ultra-Magnum (aka 7mm RSAUM), is giving stellar accuracy with cutting-edge, ~180 grain bullets, powder charges in the mid-50 grain range and velocities about 2800+ fps in long barrels. Beyond pure efficiency, the RSAUM’s modern, “short and fat” design helps ensure fine accuracy relative to older, longer cartridge designs of similar performance.

Recent design advances are yielding bullets with here-to-fore unheard-of ballistic efficiency; depending on the cartridge, they can make or break ones decision. Ballistic coefficients (“BC” — a numerical expression of a bullet’s ballistic efficiency) are soaring to new heights, and there are many exciting new avenues to explore.

The ideal choice [involves a careful] balancing act between bullet BCs, case capacity, velocity, barrel life, and recoil. But, as with new-car decisions, choosing can be half the fun!

Factors to Consider When Evaluating Cartridges
For competitive shooters… pristine accuracy and ballistic performance in the wind are critical. Flat trajectory benefits the hunter who may shoot at long, unknown distances (nowadays, range-finders help). However, this is of much less importance to competitors firing at known distances.

Recoil is an issue, particularly when one fires long strings during competition, and/or multiple strings in a day. Its effects are cumulative; cartridges with medium/heavy recoil can lead to shooter fatigue, disturbance of the shooting position and lower scores.

For hunters, who may only fire a few shots a year, recoil that does not induce flinching during sight-in, practice and hunting is a deciding factor. Depending on their game and ranges, etc., they may accept more recoil than the high-volume High Power or Long Range competitor.

Likewise, throat erosion/barrel life is important to competitive shooters, who fire thousands of rounds in practice and matches, vs. the medium/big game hunter. A cartridge that performs well ballistically with great accuracy, has long barrel life and low recoil is the competitive shooter’s ideal. For the hunter, other factors may weigh more heavily.

Cartridge Efficiency and Energy — Another Perspective
Lapua staffer Kevin Thomas explains that efficiency can be evaluated in terms of energy:

“Cartridge efficiency is pretty straight forward — energy in vs. energy out. Most modern single-based propellants run around 178-215 ft/lbs of energy per grain. These figures give the energy potential that you’re loading into the rifle. The resulting kinetic energy transferred to the bullet will give you the efficiency of the round. Most cases operate at around 20-25% efficiency. This is just another way to evaluate the potential of a given cartridge. There’s a big difference between this and simply looking at max velocities produced by various cartridges.”

Permalink Bullets, Brass, Ammo, Reloading 3 Comments »
August 5th, 2018

Semi-Auto 17 HMR Rifle — Savage’s A17

Savage 17 HMR .17  A17 A-17 varmint hunting semi-auto rifle accurateshooter.com

One of our favorite cartridges for small varmints is the 17 HMR. Yes, the newer 17 WSM rimfire has better ballistics, but 17 HMR ammunition is considerably less expensive, and you have a much larger selection of rifles and pre-chambered aftermarket barrels. And out to 150 yards or so the 17 HMR is great on ground squirrels and prairie dogs.

If you are looking for a 17 HMR varmint rifle, one rig you should definitely consider is the Savage A17. Now that this model is offered in a nice laminated thumbhole stock, you can get a fine little 17 HMR rifle for about $450.00. We much prefer the laminated stock A17 over the basic Tupperware version.

Savage A17 thumbhole stock

How does an A17 shoot? That question was answered a couple seasons back by Varminter.com in a First Hunt Report. Accurate and affordable, the Savage A17 is also the first .17 HMR to feature a delayed blow-back action. Eric Mayer, Editor of Varminter.com, put the semi-auto Savage A17 through its paces.

CLICK HERE for Savage A17 First Hunt Report on Varminter.com

Mayer wanted to see how the new Savage would perform, accuracy-wise, and he also wanted to see how the A17 fared in the field. Mayer achieved one-MOA accuracy with the Savage A17 using the latest CCI-brand ammo, and he demonstrated the A17 is wickedly effective on ground squirrels. Below we’ve provided highlights from Varminter.com’s Savage A17 First Hunt Report.

“I [collected] as many versions of the currently available .17 HMR ammunition as I could get my hands on. I had already picked-up and tested the new CCI A17 ammunition, so I filled up my ammo safe with other CCI ammunition, as well as Hornady and Winchester, including the lead free 15.5 grain NTX versions, also from Hornady and Winchester. After spending some time at the bench, I saw that this rifle shot the CCI A17 ammunition best, with most groups hovering right around 1″ to 1.20″ at one hundred yards, and some of the other ammo choices in the 1.25″ to 1.50″ range. This was with a warm barrel and in-between cleanings during the break-in process.”

Savage 17 HMR .17  A17 A-17 varmint hunting semi-auto rifle accurateshooter.com

Mayer found the A17 was easy to maintain: “I was very impressed by the ease of pulling the rifle apart for cleaning out in the field. Even with the scope mounted, I was able to quickly and easily remove the parts needed to give me complete access to the barrel through the breach, so cleaning was a breeze.”

A17 Reliability Lessons — Seat Those Rotary Magazines Correctly Folks
Some early A17 purchasers have noted occasional failures to feed. We believe this is because the magazine was not fully seated (and locked in place) in the firearm. The experience of Varminter.com’s Editor seems to confirm this. Mayer reports “As I began to shoot the rifle, I experienced what a few others have reported, with the magazine falling out while shooting. I quickly realized that I was not snapping the magazine into place every time. I found that popping in the magazine while the bolt was pulled, or locked back, resolved the issue. I did have a few failures to feed, but only on some of the older ammunition I was shooting, namely the first year Hornady ammo and the lead free ammo (which is about 3-4 years old). The newer ammo did not have any issues and functioned well, even while shooting some 10-round ‘mag-dumps’. The trigger is on the heavy side.”

A17 Reliability Shown in Video
The Savage A17 went through a very thorough manufacturer’s testing process before it was released to the market. In fact Savage put over 500,000 test rounds through A17 prototypes. When AccurateShooter.com tested the A17 at Media Day — it worked flawlessly, so long as you make sure the magazine is fully seated. We had zero issues, making us think that reported issues may be related to “driver error”; specifically not seating the magazine properly. Watch AccurateShooter.com video with rapid fire sequence.

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August 5th, 2018

Get Concealed Carry Permits Honored in 32 States

concealed carry permit CarryGuard NRA Utah Virginia permit class convention

Serious competitive shooters and hunters often travel across state lines to pursue their hobbies. And many of those same firearms owners have pistol carry permits for their home state. Now wouldn’t it be great if you could obtain a permit package that is recognized in 32 states? Believe it or not, that IS possible. If you obtain BOTH the Utah (UT) and Virginia (VA) Non-Resident Carry Permits, your carry privileges will be honored in 32 states, as shown in this map from USACarry.com.

concealed carry permit CarryGuard NRA Utah Virginia permit class convention

So how do you get the UT/VA Permits that covers you in 32 States? Well one of the simplest ways is to attend a Carry Permit Class that specifically covers all the requirements. One such course will be offered at the NRA Carry Guard EXPO in Richmond, Virgina, September 14-16, 2018.

This $65.00 course covers the entire process for obtaining the Utah Non-Resident Carry Permit, as well as the VA Non-Resident Permit. (It also covers the VA Resident permit for Virginians who don’t already have a VA permit). This course includes completion of the applications for both Utah and Virginia, required course instruction, fingerprints and photos. Yes, this course includes fingerprinting AND passport photos! That’s all included in the $65.00 price*.

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