February 15th, 2018

Quarter-MOA, Half-MOA? How Much Precision Is Really Enough?

Jim See Elite Accuracy
This impressive 15-round group was shot by Jim See of Elite Accuracy.

Different shooting disciplines demand different levels of precision/accuracy. In the rapid-fire 3-Gun game, you could probably “clean” most stages with a 2-MOA rifle. By contrast, in the short-range group benchrest game, to compete with the best, you’ll need a rifle that shoots in the “ones” (i.e. 0.1-0.19 MOA) in perfect conditions. In 1000-yard F-Class competition, the top shooters want a rifle that will hold one-third-MOA of vertical at that distance.

What is your standard of accuracy? How good is “good enough”. Jim See, a skilled gunsmith and successful PRS competitor, has answered that question for his tactical discipline. For the kind of matches Jim shoots, he likes to have a rifle that will hold half-MOA for five (5) shots, 3/4-MOA for 15 shots, and 1 MOA for twenty shots. Remarkably, Jim’s rifle can do that with factory ammo. Above is an impressive 15-shot group shot with .260 Remington Federal Premium Ammo.

Jim See Elite Accuracy

“I say it all the time, my loads need to print 5 under 1/2″, 10 under 3/4″, and 20 under 1″. It’s simple, if a hot barrel will keep 20 rounds fired in succession under my standard it will be a good barrel and load for Precision Match Shooting. Federal Premium Gold Metal Match .260 with Sierra bullets made the cut for me today. 15 consecutive shots under 3/4 MOA.” –Jim See

It’s said that you “can never have too much accuracy”, but there are acceptable standards for each discipline, and they’re not the same. A 100/200 yard Benchrest shooter will be sorely disappointed with a rifle/ammo set-up that can only deliver half-MOA. On the other hand, a PRS competitor like Jim See can achieve great success with a lesser degree of precision. This means you can save time and money. You can run your barrels longer between cleanings, and you don’t have to go “full OCD” when loading your ammo. The PRS shooter does not need to weigh-sort primers, or load powder to single-kernel standards. Proof is the performance. Jim See recently took third place at the Spearpoint Shootout, and he has been a podium finisher at other events. Learn more about Jim’s gunsmithing and training operations at EliteAccuracy.com.

Download This Load Development Target

Jim’s target seemed a bit familiar. AccurateShooter.com created this Diamond and Dot Target a few years back. On each aiming point, there are high-contrast black horizontal and vertical lines for aligning your cross-hairs. The gray circle lets you see the bullet impacts above, without obliterating the red diamond, which is quite useful for precise aiming (we put fine cross-hairs on the points of the diamond). This target sheet includes data entry tables below each of the three aim points. There are many other free targets out there, but this format is very popular. We’re pleased to see Jim using it. You can download this and dozens of other FREE Targets from the AccurateShooter.com Target Page.

AccurateShooter precision load development free target

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February 15th, 2018

Shooting on a Spinning Planet — The Coriolis Effect

Whittington Coriolis Effect
Photo by Dustin Ellermann at Whittington Center Range.

The Coriolis Effect comes into play with extreme long-range shots like this (2100 yards at Raton, NM). The rotation of the earth actually moves the target a small distance (in space) during the long duration of the bullet’s flight.

Coriolis Effect Bryan Litz Applied BallisticsWhen you’re out at the range, the Earth seems very stable. But it is actually a big sphere zooming through space while spinning around its axis, one complete turn every 24 hours. The rotation of the earth can create problems for extreme long-range shooters. During extended bullet flight times, the rotation of the planet causes an apparent deflection of the bullet path over very long distances. This is the ballistics manifestation of the Coriolis Effect.

Bryan Litz of Applied Ballistics discusses explains the Coriolis Effect in his Ballistics Books and Seminars. Bryan notes that Coriolis is “a very subtle effect. People like to make more of it than it is because it seems mysterious.” In most common shooting situations inside 1K, Coriolis is not important. At 1000 yards, the Effect represents less than one click (for most cartridge types). Even well past 1000 yards, in windy conditions, the Coriolis Effect may well be “lost in the noise”. But in very calm conditions, when shooting at extreme ranges, Bryan says you can benefit from adjusting your ballistics solution for Coriolis.

Bryan explains: “The Coriolis Effect… has to do with the spin of the earth. You are basically shooting from one point to another on a rotating sphere, in an inertial reference frame. The consequence of that is that, if the flight time of the bullet gets significantly long, the bullet can have an apparent drift from its intended target. The amount [of apparent drift] is very small — it depends on your latitude and azimuth of fire on the planet.”

Coriolis Effect Bryan Litz Applied Ballistics

Coriolis is a very subtle effect. With typical bullet BCs and velocities, you must get to at least 1000 yards before Coriolis amounts to even one click. Accordingly, Bryan advises: “Coriolis Effect is NOT something to think about on moving targets, it is NOT something to think about in high, uncertain wind environments because there are variables that are dominating your uncertainty picture, and the Coriolis will distract you more than the correction is worth.”

“Where you could think about Coriolis, and have it be a major impact on your hit percentage, is if you are shooting at extended range, at relatively small targets, in low-wind conditions. Where you know your muzzle velocity and BC very well, [and there are] pristine conditions, that’s where you’re going to see Coriolis creep in. You’ll receive more refinement and accuracy in your ballistics solutions if you account for Coriolis on those types of shots. But in most practical long-range shooting situations, Coriolis is NOT important. What IS important is to understand is when you should think about it and when you shouldn’t, i.e. when applying it will matter and when it won’t.”

The Coriolis Effect — General Physics
The Coriolis Effect is the apparent deflection of moving objects when the motion is described relative to a rotating reference frame. The Coriolis force acts in a direction perpendicular to the rotation axis and to the velocity of the body in the rotating frame and is proportional to the object’s speed in the rotating frame.

A commonly encountered rotating reference frame is the Earth. The Coriolis effect is caused by the rotation of the Earth and the inertia of the mass experiencing the effect. Because the Earth completes only one rotation per day, the Coriolis force is quite small, and its effects generally become noticeable only for motions occurring over large distances and long periods of time. This force causes moving objects on the surface of the Earth to be deflected to the right (with respect to the direction of travel) in the Northern Hemisphere and to the left in the Southern Hemisphere. The horizontal deflection effect is greater near the poles and smallest at the equator, since the rate of change in the diameter of the circles of latitude when travelling north or south, increases the closer the object is to the poles. (Source: Wikipedia)

Permalink Shooting Skills, Tech Tip 3 Comments »
February 15th, 2018

Save with 2018 Rebates on Guns and Gear

Gun gear reloading rebate optics burris

There a number of good rebate programs going on right now, but some conclude in just a few weeks. To take advantage of these deals you’ll need to start your shopping soon. Here are some current Rebate Programs for rifles, loading equipment, and shooting accessories. You can save up to $125.00 with these direct Rebate offers, or you can get bullets worth over $175.00 (500 count). The RCBS promo runs through 2/28/2018, while the Browning and Winchester rebates go through 3/31/2018. Hornady’s Get Loaded promotion is good all year

1. Browning Sales Tax Event — 10% Rebate

Browning Spring 2018 Sales Tax Rebate

When you buy a new Browning firearm at retail between February 1 and March 31, 2018, you can receive a rebate of 10% of the purchase price to reimburse you for your state sales tax. This applies to a wide range of Browning firearms including rifles, shotguns, and pistols. All purchasers must be citizens or legal residents of the United States

Start Date: February 1, 2018
End Date: March 31, 2018
Redemption Deadline: April 15, 2018

Get Rebate Form HERE
NOTE: Browning Rebates must be Redeemed Online

2. RCBS February 2018 Bucks or Bullets Promotion

Rcbs bucks bullets promotion Spring 2018 Rebate

Get Bucks or Bullets with purchase of Qualifying RCBS Products. This offers buyers a choice of money or bullets. You get a $10 Prepaid Card or 100 Free Bullets with: Qualifying Die Sets, Hand Priming Tool, Universal Hand Priming Tool, Trim Mate Case Prep Center, or a M500 Mechanical Scale. Alternatively, you can get a $50 Prepaid Card or 500 Free Bullets with: Rock Chucker Supreme Kit, Universal Case Prep Center, Explorer or Explorer Plus Kits, Pro Chucker 5 or 7, or an Ultrasonic Case Cleaner 2.

Start Date: February 1, 2018
End Date: February 28, 2018
Redemption Deadline: March 31, 2018

Shop Qualifying Items HERE
Get Rebate Form HERE

3. Winchester Spring Warm-Up Rebates

Winchester Spring 2018 Rebate

Here’s a great deal if you are looking for a new hunting rifle. Purchase any NEW Winchester XPR rifle and receive $75 via mail-in rebate. With this promotion, you can buy a new XPR for just $264.99 after rebate. You can also save $25, $50, or $100 on qualifying Winchester shotguns.

Start Date: February 1, 2018
End Date: March 31, 2018
Redemption Deadline: April 15, 2019

See Qualifying XPR Rifles HERE
Submit Rebate HERE

Hornady Get Loaded 2018 Rebate

Hornady Spring 2018 Rebate

Receive 100 or 500 Free Bullets when you purchase select Hornady Products. The 500 Free Bullets (worth up to $181.05) are available with purchase of one of these Lock-N-LoadĀ® products: Iron Press Kit, Classic Kit, Classic Kit Deluxe, Classic Kit with Auto Charge, Ammo Plant, AP Press, Case Prep Center, Deluxe Control Panel, or Hot TubĀ® Sonic Cleaner. NOTE: Hornady requires you to pay for return shipping on the bullets. You must submit a check for the shipping with your rebate form. No check, no bullets — got it?

Start Date: January 1, 2018
End Date: December 31, 2018
Redemption Deadline: February 15, 2019

Shop Qualifying Items HERE
Get Rebate Form HERE

RCBS Rebate Recommendation from EdLongRange. We welcome reader submissions.
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