January 18th, 2020

Accuracy Vs. Precision — They Are Not the Same Thing

Applied Ballistics Accuracy Precision
This image is from Modern Advancements in Long Range Shooting, Volume 2.

The next time a shooter comes up to you at the range, and says: “My rifle shoots one-third MOA all day long”, challenge him to put a first-round hit on a 1/2 MOA plate at 1000 yards. There’s a difference between shooting small groups at close range (Precision) and “on-target” Accuracy at long range.

Article by Applied Ballistics, LLC
Just how much better is a 0.5 MOA rifle vs. a 1 MOA rifle? Is it worth chasing quarter-MOA if you have half-MOA rifle? This is an important question. If you look across Facebook you will find scores of shooters posting 1/3-MOA or 1/4-MOA shot groups [usually at 100 yards]. Some of those guys are spending countless hours trying to chase that golden quarter-MOA group.

Don’t take this statement the wrong way, having a good, consistent rifle is a key to success. But accuracy is extremely important to long range shooting. Having a precision (0.5 MOA) rifle, but not having put the time in to practice accuracy (hitting a 0.5 MOA plate first shot at 1000 yards) is counter-productive. [Editor: By this, we mean that you can have a rifle capable of shooting small groups at 100 yards, but you won’t see that gun’s full potential unless you can practice and perfect the skills of long-range shooting. Successful long range shooting demands more than precision alone.]

What if, your goal was to produce 5-shot, sub-half-MOA groups at 1000 yards instead of 100 yards? Think about how much more you would be including in the learning process, especially that all-important factor: managing the wind! Here is a good article that talks about Precision vs. Accuracy: Hitting Targets at Long Range.

This is not intended to say that precision is not important; rather it is intended to show that balance is important. You can use WEZ to do your own studies on this very subject, and it might be surprising to the shooter just how much you don’t gain by chasing precision over accuracy. Two books which cover this subject really well are Accuracy and Precision for Long Range Shooting and Modern Advancements in Long Range Shooting Vol 2.

Here’s a stunning combination of Precision (small group) WITH accuracy (centered on target). Yep that’s ten shots at 1000 yards, all in the middle of the target:
Scott Nix Dasher Record

Video Demonstrates Amazing 1000-Yard Accuracy AND Precision

Watch the video. You can see the group form up, shot by shot. It’s pretty amazing. Scott’s first shot (at the 45-second mark of the video) was right in the X-Ring, and four of Scott’s first five shots were Xs. That’s drilling them!

Comments

“Accuracy with precision is the route for me. It is not an either/or game. If I have a precision rifle (0.25 MOA or less) and I practice to be accurate, then high scores will be the result — Jim Borden

“I would agree for PRS, hunting, and to a certain extent F-Class. However, for 1000-yard IBS benchrest competition, 0.5 MOA groups in good conditions will almost always loose the relay.” — James B

“Another thought is that [at 1000 yards] a 1 MOA gun with single-digit standard deviations [may] out shoot a 0.5 MOA rifle with standard deviations of 20+ fps.” — Beard Owens

“Both… you need both: Accuracy AND Precision. I competed in varmint matches — we shot small silhouettes at 600 yards. I started with a factory .260 Rem rifle that was 0.8 MOA on a good day. I typically hit 8-9 of 20 targets, but rarely nailed the small chickens — which had a hit zone just 4″ in diameter. I then started using a semi-custom 6mmBR rifle that could reliably deliver 1/4 MOA at 100 yards (honest). My hit count on the silhouettes zoomed to 15-18, and suddenly the chickens were going down. In that game — small targets at 600 yards — there was no substitute for precision.” — Paul McM

Permalink Competition, News, Shooting Skills 2 Comments »
January 18th, 2020

Flash-Hole First Aid — Clearing Obstructions in Flash-Holes

Flash-hole reamer

Even with high-quality brass from Lapua, Norma, and RWS, occasionally you may find one or two cases per box which have a small flake or obstruction in the flash-hole. This will appear like a thin crescent on one side of the flash hole (see photo). You should inspect ALL new brass before loading to identify any pieces with a partially-obstructed flash hole. It’s a good idea to remove any flake or thin crescent left as an artifact of the flash-hole forming process. Because the flash-hole itself is normally centered and of the correct diameter, it is not necessary to ream the flash-hole to a larger diameter. All you really need to do is remove the small obstruction(s). This can be done quickly with inexpensive tools.

Use a Small Pin Vise to Remove Flash-Hole Obstructions
Folks have asked if there is a tool that can remove obstructions from a Lapua small, BR-sized flash hole without opening the hole size. The Lapua PPC/BR flash hole is spec’d at 1.5mm, which works out to 0.059055″. Most of the PPC/BR flash-hole uniforming tools on the market use a 1/16″ bit which is nominally 0.0625″, but these often run oversize — up to 0.066″.

If you want to just clear out any obstructions in the flash hole, without increasing the flash hole diameter, you can use an inexpensive “pin vise” with an appropriate drill bit. For $0.99, eHobbyTools.com sells a 1.5mm drill bit, item 79186, that matches the Lapua flash hole exactly. Other vendors offer a #53 pin vise drill bit that measures .0595″ or .060″ (depending or source). An 0.0595″ bit is close enough. You can find pin vises and these small-diameter drill bits at hobby stores.

Pin vises Lapua Flash hole

For quite some time, Sinclair Int’l has sold a similar device for small (PPC and BR-size) flash holes. Like the 07-3081 unit for large flash holes, the 073000 Reamer for small flash holes works from the outside, so it can index off the primer pocket. It reams to .0625″, and also costs $29.99. The standard dimension for Lapua 220 Russian and 6mmBR flash holes is 1.5mm or .0590″. This tool will permit standard-size decapping rods with .0625″ tips to work without binding. However, note that both Forster and Redding normally supply .057″ decapping pins with their PPC and BR dies. So, it is NOT necessary to ream your Lapua BR/PPC flashholes, unless you prefer to do so for uniformity. It IS, however, a good idea to check BR/PPC flash holes for burrs before loading the first time.

AccurateShooter Sinclair Flash Hole Reamer

NOTE: If you purchase either the 073081 or 073000 Sinclair Flash Hole Reamer tools, we recommend you mic the cutter tip before you process a bunch of cases. Sometimes a tip comes through that is oversize. This will ream the flash holes larger than you may intend.

Permalink Bullets, Brass, Ammo, Reloading 2 Comments »