January 7th, 2013

New RCBS Summit Single-Stage Press

RCBS Summit Reloading PressRCBS has a new made-in-USA single-stage reloading press. With its innovative “moving die/static cartridge” design, the new RCBS Summit Press definitely demonstrates “out of the box” thinking. Unlike other presses, the case does not move. Rather, the reloading die comes down to the case. With the press bolted on your reloading bench, all operations of the Summit take place ABOVE the bench-top.

The new Summit Press features a rugged cast-iron frame with all-steel linkages. The press is very strong with minimal flex and slop in use. This allows you to “bump” your case shoulders and seat bullets with great precision and repeatability. The handle can be switched from right to left side (good for southpaws), and the open-front design provides good access, facilitating quick die changes. The 4.5-inch opening allows you to work with tall cases. Beneath the shell-holder is a spent primer catcher.

The new Summit press has a beefy 2-inch diameter ram, with compound linkages for plenty of leverage. A zerk fitting is included for easy lubrication. The press will accept larger bushings for oversize 1-inch dies.

Summit Press for $207.94
The new Summit Press (RCBS item #09290) lists for $269.95. However, Midsouth Shooters Supply offers the Summit Press for $207.94. An optional short handle costs $15.27 at Midsouth ($19.95 MSRP).

RCBS Summit Reloading PressRCBS Summit Press Features:

• Bench-top operation
• Massive 2-inch diameter ram
• Ambidextrous handle
• Compound leverage
• 4.50-inch operating window
• Spent primer catcher
• Full frontal access
• Accepts bushings for 1″ die bodies
• Press adapter bushing
• Zerk lubrication fitting
• Made in USA

Product tip by EdLongrange. We welcome reader submissions.
Permalink New Product, Reloading 10 Comments »
January 7th, 2013

G1 vs. G7 Ballistic Coefficients — What You Need to Know

The better, up-to-date ballistics programs let you select either G1 or G7 Ballistic Coefficient (BC) values when calculating a trajectory. The ballistic coefficient (BC) of a body is a measure of its ability to overcome air resistance in flight. You’ve probably seen that G7 values are numerically lower than G1 values for the same bullet (typically). But that doesn’t mean you should select a G1 value simply because it is higher.

Some readers are not quite sure about the difference between G1 and G7 models. One forum member wrote us: “I went on the JBM Ballistics website to use the web-based Trajectory Calculator and when I got to the part that gives you a choice to choose between G1 and G7 BC, I was stumped. What determines how, or which one to use?”

The simple answer to that is the G1 value normally works better for shorter flat-based bullets, while the G7 value should work better for longer, boat-tailed bullets.

G1 vs. G7 Ballistic Coefficients — Which Is Right for You?
G1 and G7 refer both refer to aerodynamic drag models based on particular “standard projectile” shapes. The G1 shape looks like a flat-based bullet. The G7 shape is quite different, and better approximates the geometry of a modern long-range bullet. So, when choosing your drag model, G1 is preferrable for flat-based bullets, while G7 is ordinarily a “better fit” for longer, boat-tailed bullets.

G1 G7 Ballistic coefficients

Drag Models — G7 is better than G1 for Long-Range Bullets
Many ballistics programs still offer only the default G1 drag model. Bryan Litz, author of Applied Ballistics for Long Range Shooting, believes the G7 standard is preferrable for long-range, low-drag bullets: “Part of the reason there is so much ‘slop’ in advertised BCs is because they’re referenced to the G1 standard which is very speed sensitive. The G7 standard is more appropriate for long range bullets. Here’s the results of my testing on two low-drag, long-range boat-tail bullets, so you can see how the G1 and G7 Ballistic coefficients compare:

G1 BCs, averaged between 1500 fps and 3000 fps:
Berger 180 VLD: 0.659 lb/in²
JLK 180: 0.645 lb/in²

The reason the BC for the JLK is less is mostly because the meplat was significantly larger on the particular lot that I tested (0.075″ vs 0.059″; see attached drawings).

For bullets like these, it’s much better to use the G7 standard. The following BCs are referenced to the G7 standard, and are constant for all speeds.

G7 BCs:
Berger 180 VLD: 0.337 lb/in²
JLK 180: 0.330 lb/in²

Many modern ballistics programs, including the free online JBM Ballistics Program, are able to use BCs referenced to G7 standards. When available, these BCs are more appropriate for long range bullets, according to Bryan.

[Editor's NOTE: BCs are normally reported simply as an 0.XXX number. The lb/in² tag applies to all BCs, but is commonly left off for simplicity.]

Permalink Bullets, Brass, Ammo, Reloading 8 Comments »
January 7th, 2013

SHOT Show Start to Finish in Ninety-Six Seconds

SHOT Show 2012 Las VegasIf you’ve never visited SHOT Show, you may not know what a huge operation it represents. Filling the Sands Expo and Convention Center in Las Vegas with 1600 exhibits covering 630,000 square feet is like building a small indoor city from scratch. Starting from bare floors and walls, workers labor furiously to assemble 1600+ booths before Show attendees storm the gates. And then, a few days later, all those exhibits must be torn down, boxed up, and shipped out. It’s a Herculean task. And here, with the aid of time-lapse photography, you can experience the entire SHOT Show in just 96 seconds.

In this short video filmed at SHOT Show 2012, time-lapse photography is used to compress the entire SHOT Show into one 96-second montage. Watch a small section of the Show floor from start to finish (including prep time) at this year’s event. It’s a fun video to watch — you can “experience” an entire Show day in a mere 10 seconds. For example, Tuesday starts at the 0:33 second mark and Wednesday begins just 10 seconds (of video time) later. Appropriately, the soundtrack is “Flight of the Bumblebee” by Nikolai Rimsky-Korsakov.

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