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June 28th, 2009

TECH TIP: Keep Your Rifle Level for Better Scores

Experienced marksmen know they should keep their rifles level when shooting. But they may not understand exactly what happens if they allow their rifle to be canted (tilted left or right), even a few degrees. While the physics are complicated to explain, here’s what you need to know: if you cant your rifle to the left, your shots will impact to the left, and lower, than your point of aim. Likewise, if you cant your rifle to the right, your bullets will impact low and right.

Effects of Rifle Canting
The effects of rifle canting are explained in great detail on the Long Shot Products Ltd. website. There, you’ll find a technical discussion of the Physics of Rifle Canting, plus a page with Sample Targets shot with canted rifles.

Referring to the above illustration, the Long Shot Products article explains: “Notice how the trajectory of the vertical hold stays within the vertical plane, so when the projectile drops, it drops into the line of sight and down to the center of the target. The trajectory of the cant hold does not achieve the same height as the trajectory of the vertical hold and the projectile diverges from the line of sight, thereby missing the target.”

The Long-Shot article makes two other important points. First, cant error increases with distance, and second, cant-induced windage errors are worsened by mounting your scope high above the bore axis:

“This component of cant error becomes more significant at more distant targets due to the increased original included angle between the line of sight axis and the bore axis (more elevation compensation) at the vertical hold.”

“Use of large-diameter objective scopes, mounted high off the barrel, exacerbates the cant error problem. To keep the scope elevation knobs centered for maximum adjustment, precision shooters sometimes use elevation-compensated scope mounting rings or bases. Although this solves the adjustment problem, it greatly exaggerates cant error because the distance between the bore axis and the line of sight axis increases and the included angle between the sight axis and the bore is larger, producing more windage error when canting.”

Test Targets Reveal Cant Errors
The Long Shot Products Ltd. website also displays actual Test Targets showing the effects of canting error. These targets were shot with air rifles and rimfire rifles, but the same effects can and will occur with centerfire rifles. Shown below is a target shot at 50 yards with a Feinwerkbau .22LR match rifle using RWS Match ammo (1012 fps MV). As you can see, canting the rifle 20 degrees to the left produced a huge movement of the point of impact. The shots from the canted rifle impacted 1.81″ Left, and 0.6″ below the point of aim.

CLICK HERE to view more Canted Rifle TARGETS.

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June 28th, 2009

Australian Team Wins WBC10 — Bukys & Boyer Top Two-Gun

The underdog Australians came and conquered at the 10th World Benchrest Championship just concluded in South Africa. In Team competition, the Australia “A” squad took the Two-Gun Gold. Finishing second was the USA “A” Team, while Team Italy took third place. Congratulations to Australia’s winning team: Brendan Atkinson, Stuart Elliott, Paul Sullivan, and Craig Whittleton. James Kelbly has posted: “Australia has been knocking on the door for many championships. Just got off phone with Roland Thomsen in South Africa and he told me conditions were as tough as he has seen. I would like to congratulate the organizers from South Africa for putting on a great match.”

Australia Benchrest Championship

In individual competition, Gene Bukys is the new Two-gun Grand Agg World Champion. Gene shot great throughout the match to finish at the top with a 0.2798 MOA Two-gun Agg. Second in the Two-gun was legendary Tony Boyer, and Australian Brendan Atkinson finished third. Bukys also won the LV Grand Agg.

You can download all the individual and team scores at the WBC10 website. Despite superb performances by Bukys and Boyer, the Aussies beat the favored Americans by more consistent shooting in very challenging conditions at 200m. If the Americans wish to get back on top, it may be time to experiment with higher-BC bullets for the 200m events, something Lester Bruno and other western-states Benchresters have been doing recently. Team USA was leading through Day 3, but the Aussies took the lead on Day 4 with superior team shooting in the HV 200m stage. Congrats to the winning Australian team!

Brendan Atkinson AustraliaTen Tips for Benchrest Shooters
Australian Brendan Atkinson has authored an excellent article, Ten Tips for Benchrest Shooters. Tip Number 10 is “Never, Ever, Give Up”. This positive attitude surely helped Brendan and his teammates achieve a come-from-behind victory at WBC10:

“You are only as good as your last group/aggregate. In 1980, I once started a 100-yard aggregate with a 1.026 group and then went on to win the overall match. I took the attitude that now that the A target was out of the way I was going to shoot nine very small groups. It was a very rough day, and took a lot of concentration to put shots together. In looking back, it was one of my most enjoyable wins. One should never give up –- even if a disastrous group does happen. Every shoot should teach you something –- even when you lose, don’t lose the lesson. Once a shot is fired on the business target, it is up there forever. There is nothing you can do about it, except get on with it. Do your very best, and curse about the lost shot later, in private.”

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