The Importance of Accuracy in a Carbine

February 22, 2017 1 Comment

The Importance of Accuracy in a Carbine

By increasing our margin of error, we decrease the amount of precision required to the absolute minimum, which means making more hits, and in less time, at the same level of marksmanship skill.

In working with new 3-Gunners (both formally at the Tactical Performance Center and informally at local matches), I commonly hear them refer to themselves as “not good enough” to see the benefits of an accurate rifle/ammunition combination. I’ve also heard more, shall we say, “tactically-minded” shooters downplay the importance of accuracy in the carbine, so long as it’s capable of making “combat-effective” hits.

Rather than get highly technical, I’ll simply give you this anecdote:

In 3-Gun matches in the western U.S., it’s not uncommon to encounter targets 8-10” in size at 350-400 yards, making the target roughly 2 MOA in size at the smallest (actually slightly smaller, since 2 MOA is actually 8.3776” at 200 yards, but that’s neither here nor there). That means that in order to guarantee a hit on target, I need a properly zeroed rifle capable of holding a 2 MOA group. Then I need to be able to do my job and put the optic’s reticle (or iron sights, if you’re a masochist) on the target, and fire the rifle without influencing that sight alignment.

So am I “good” with a 2 MOA rifle if I need to shoot 2 MOA targets frequently?

In theory, yes. In reality...nope. While it’s doable, it requires a far greater level of precision on the shooter’s part. Let’s take the example of the shooter with a 2 MOA rifle/ammo combo, who endeavors to engage an 8” plate at 400 yards. The rifle is well-zeroed to the center of a 2 MOA group, but on our shooter’s first shot, fires .75 MOA to the right of it’s zero point (still well within the established accuracy of the rifle). Combined with a 1 MOA left-to-right wind (3mph at 400yds for my personal 5.56 match loading), our shooter has only a quarter-minute (1” at 400yd) margin for error to the right of dead center target. If our shooter’s rifle is misaligned more than an inch right of center, his shot will be a miss to the right.

Now, let’s take the same shooter, same target, but substitute in a .75 MOA rifle/ammo, which is not unreasonable to expect from a decently-built AR15 with accurate ammunition. Now at the far end, it will shoot .375 MOA right of zero at maximum (rather than our 2 MOA example). With the same wind on the same 8” plate at 400 yards, our shooter now has a .625 MOA margin of error to the right of target.

When we increase our margin of error for what an “acceptable” shot is, we then require less refinement in the relationship between sights and target. In other words, as soon as we see the sights within our target area, we can fire the shot and have good expectation of a hit. For practical disciplines (combat, competition excepting benchrest, hunting, et cetera), this is the only accuracy required of the shooter; he needs to be accurate enough on each shot to make a hit, and that’s all. When we make the rifle more accurate, we take away one layer of accuracy and skill that the shooter has to apply in the field, which in turn contributes to greater speed, and more consistently good performance.

The ability to make an acceptable hit under a time constraint is a natural requirement for all practical disciplines. In practical competitions like 3-Gun, hits at speed equal victory! In High-Power or Precision Rifle competition, time is limited and calm winds don’t last forever! On the hunt, game animals may only expose themselves (or their vital areas) for a short window, combat being much the same - albeit with far more dire consequence for failure.

Accurate rifles enhance our speed both by lessening the requirement for perfect sight alignment on center-target and by allowing us to call shots with greater ease and speed. Let’s return to our 8” steel plate at 400 yards, using a .75 MOA rifle. If our shooter recognizes that his aiming point was within 5” of the target’s center (assuming calm conditions) when the bullet left the barrel, he knows that his bullet will hit the target. Confirmation will come with visual and audio feedback (watching and hearing the target be struck).

In 3-Gun specifically, a Range Officer will also call “HIT” to indicate that he’s witnessed the hit as well (this also serves as a confirmation for the shooter, though if you’re just learning from the RO that you’ve hit the target then you’re behind the power curve). Great speed in long-range shooting for 3-Gun can be found by shortcutting all these forms of confirmation and relying solely on shot-calling. This is the method great 3-gunners use to crush long-range rifle stages, though it comes with the obvious risk of outrunning RO spotters or not realizing a miss because one’s shot-calling ability is not quite honed.

For context, flight time of my personal 5.56 load is about .5 seconds at 400 yards. Typically an RO will recognize and call “hit” within another .75-1.2 seconds (assuming they’re “on the ball”), so to wait for the RO to call “hit” adds 1.2-1.7 seconds per target over the shot-calling method. The “thwack” of the steel will reach the shooter 1.14 seconds after the hit, or 1.64 seconds after the shot is fired (Speed of sound = ~1050 fps, should cover 1200ft in 1.14 seconds). I might also add that many rocks on this earth, as well as many steel target hangers, sound like a hit but are not considered a scoring hit in competition.

By increasing our margin of error, we decrease the amount of precision required to the absolute minimum, which means making more hits, and in less time, at the same level of marksmanship skill.

This type of performance and accuracy in a carbine need not be overly expensive or laborious, though! The AR-15 (and many post-AR carbines such as the SCAR, ACR, etc.) are inherently very easy to make accurate, if they don’t come that way out of the box (and a $1200 DPMS 3G2 is a plenty accurate solution).

Ammunition is a bit of a sticky wicket in that “match-grade” accurate ammunition is typically expensive, though there are a few exceptions. I’ve found that Hornady’s 75 grain “Steel Match” ammo is quite accurate in several of my rifles, if ballistically somewhat unimpressive (2570 fps from my 18” barrel is a bit tame). Steel Match costs around ¢40/round, or ¢10 more than the cheapest reliable bulk “blaster” M193 clones such as PMC Bronze or Wolf Gold (and about the same as Federal/American Eagle M193).

Thanks to my sponsors, Taran Tactical Innovations, Berry's Manufacturing, Leupold Optics, PROOF Research, MGM TargetsSoundGear, and Tactical Performance Center

-Brian Nelson, TPC Instructor



1 Response

Sphamandla
Sphamandla

March 14, 2017

I need training

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