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August 1st, 2019

Win Big Prize Packages with August Gearbox Giveaways

Gearbox Giveaway Contest August

To help celebrate National Shooting Sports Month (NSSM), rifle and gear manufacturers are offering big prize packages — the Gearbox Giveaways. Enter to win rifles, pistols, ammo, and other valuable prizes. Many of the Gearbox packages are worth over $3000 with the most valuable package worth over $5000! Enter as many of the Gearbox Giveaways as you choose. You can’t win if you don’t enter.

You’ll find all the Gearbox Giveaways on the NSSF website. Shown below are TEN current Gearbox Giveaways ranked in order of value — starting with the most valuable prize package. Good luck!

Gearbox GiveAway Page — SEE ALL Prize Packages »

Gearbox Giveaway Contest August
ENTER TO WIN FN SHOOTING SPORTS GEARBOX. MSRP $5632.00

Gearbox Giveaway Contest August
ENTER TO WIN THE MOSSBERG SHOOTING SPORTS GEARBOX. MSRP $4024.00

Gearbox Giveaway Contest August
ENTER TO WIN PHOENIX WEAPONRY SHOOTING SPORTS GEARBOX. MSRP $4002.00

Gearbox Giveaway Contest August
ENTER TO WIN SIG SAUER SHOOTING SPORTS GEARBOX. MSRP $3304.64

Gearbox Giveaway Contest August
ENTER TO WIN DANIEL DEFENSE SHOOTING SPORTS GEARBOX MSRP $2953.00

Gearbox Giveaway Contest August
ENTER TO WIN AERO PRECISION SHOOTING SPORTS GEARBOX. MSRP $2883.00

Gearbox Giveaway Contest August
ENTER TO WIN RUGER SHOOTING SPORTS GEARBOX. MSRP $2767.00

Gearbox Giveaway Contest August
ENTER TO WIN GLOCK SHOOTING SPORTS GEARBOX. MSRP $2426.99

Gearbox Giveaway Contest August
ENTER TO WIN AGUILA AMMUNITION SHOOTING SPORTS GEARBOX. MSRP $1416.00

Gearbox Giveaway Contest August
ENTER TO WIN RCBS + HOPPE’S + CHAMPION TARGET + BUTLER CREEK GEARBOX. MSRP $1376.25

Permalink Bullets, Brass, Ammo, Handguns, Hot Deals, News, Tactical 1 Comment »
August 1st, 2019

Ballistics TIP: How Altitude and Air Pressure Affect Bullet Flight

Trajectory of Bullet fired at Sea Level

Trajectory of Bullet fired at 20,000 feet

You can do your own experimental calculations using JBM Online Ballistics (free to use). Here is an extreme example, with two printouts (generated with Point Blank software), one showing bullet trajectory at sea level (0′ altitude) and one at 20,000 feet. For demonstration sake, we assigned a low 0.2 BC to the bullet, with a velocity of 3000 fps.

Suunto AltimeterOne of our readers asked “What effect does altitude have on the flight of a bullet?” The simplistic answer is that, at higher altitudes, the air is thinner (lower density), so there is less drag on the bullet. This means that the amount of bullet drop is less at any given flight distance from the muzzle. Since the force of gravity is essentially constant on the earth’s surface (for practical purposes), the bullet’s downward acceleration doesn’t change, but a bullet launched at a higher altitude is able to fly slightly farther (in the thinner air) for every increment of downward movement. Effectively, the bullet behaves as if it has a higher ballistic coefficient.

Forum member Milanuk explains that the key factor is not altitude, but rather air pressure. Milanuk writes:

“In basic terms, as your altitude increases, the density of the air the bullet must travel through decreases, thereby reducing the drag on the bullet. Generally, the higher the altitude, the less the bullet will drop. For example, I shoot at a couple ranges here in the Pacific Northwest. Both are at 1000′ ASL or less. I’ll need about 29-30 MOA to get from 100 yard to 1000 yards with a Berger 155gr VLD @ 2960fps. By contrast, in Raton, NM, located at 6600′ ASL, I’ll only need about 24-25 MOA to do the same. That’s a significant difference.

Note that it is the barometric pressure that really matters, not simply the nominal altitude. The barometric pressure will indicate the reduced pressure from a higher altitude, but it will also show you the pressure changes as a front moves in, etc. which can play havoc w/ your calculated come-ups. Most altimeters are simply barometers that read in feet instead of inches of mercury.”

As Milanuk states, it is NOT altitude per se, but the LOCAL barometric pressure (sometimes called “station pressure”) that is key. The two atmospheric conditions that most effect bullet flight are air temperature, and barometric pressure. Normally, humidity has a negligible effect.

It’s important to remember that the barometric pressure reported on the radio (or internet) may be stated as a sea level equivalency. So in Denver (at 6,000 feet amsl), if the local pressure is 24″, the radio will report the barometric pressure to be 30″. If you do high altitude shooting at long range, bring along a Kestrel, or remember to mentally correct the radio station’s pressure, by 1″ per 1,000 feet.”

If you want to learn more about all aspects of External Ballistics, ExteriorBallistics.com provides a variety of useful resources. In particular, on that site, Section 3.1 of the Sierra Manual is reprinted, covering Effects of Altitude and Atmospheric Pressure on bullet flight.

Permalink Bullets, Brass, Ammo, Tech Tip 2 Comments »