Bob writes:
As a new(ish) shooter I have a question. Why would you practice with different ammunition at the range than you would use in a match? Doesn’t the different ammunition affect your accuracy and point of aim?
Well Bob, the answer is a little complicated, but basically boils down to cost. Step right in AH SAY step right in son, let me ‘splain this to ya . . .
The only real difference between “match grade” ammunition and “value pack” ammunition is consistency, and consistent ammunition closes what’s referred to as the “cone of uncertainty.”
No matter how well you load your ammunition there will always be some slight variation in muzzle velocity, and that variation is not only due to the powder charge. The temperature of the powder, the fouling in the barrel, and even the size of the bore (which expands VERY slightly when heated) dictate how fast the bullet leaves the gun.
That slight variation in velocity (and fouling) means that the bullet might go in a slightly different direction than the last one through no fault of your own or your ammunition.
To illustrate this point, imagine firing 50 rounds at a target 25 yards away. Both you and I know you’re never going to get all 50 rounds to go through the same hole, and so your imaginary target has a “pattern” of impacts roughly in the shape of a circle.
If you were to shine four lasers from the end of your barrel and through the furthest apart holes in your target (up and down, left and right) you would see an ever-expanding cone formed by these lasers.
That’s the “cone of uncertainty” for your firearm and your ammunition; every round you fire will fly within that cone until it strikes a target. That cone exists even with bench rest shooting (where the firearm is in a vice and doesn’t move) because the variation is not solely a factor of your own personal accuracy, but also that of the firearm.
Ever wonder why there are guys at the range who let their barrel cool between each shot and meticulously clean it round after round? They’re trying to eliminate those factors (heat and fouling) and shrink their cone of uncertainty.
Match grade ammunition is designed to eliminate as many factors as possible and shrink that cone of uncertainty, which is why we here at TTAG test for muzzle velocity consistency as the benchmark for how good ammunition is.
If you take a look at the latest consistency testing results you can see that the best ammunition so far is only about half as inconsistent as the worst ammunition (PLEASE ignore my handloads).
Wile the difference in consistency isn’t that great, the difference in price is gigantic. Wilson Combat 77gr .223 Rem costs about $1.50/round, but Wolf ammunition can be found for $0.25/round. That means you get to fire six rounds of Wolf for every round of Wilson Combat.
The idea behind using the cheaper ammunition: the shooter gets more practice with the rifle. Dry firing can only get you so far; in order to master the firearm you need to feel the recoil and condition yourself to follow through every single shot. For the shooter on a budget, that means sacrificing a little accuracy on the practice range in exchange for putting more holes in paper.
So long as you understand that your “cone of uncertainty” is slightly larger with the cheap stuff, there’s no problem. What should be a 1″ hole at 100 yards is now a 1.5″ or 2″ hole, but what matters is where the center of that pattern is located. As long as you’ve placed your rounds in and around your point of aim, it’s ammo well spent.
However, if by “different ammunition” you meant “different weight of bullet and vastly different velocity” then there might be an issue. You should always try to practice with ammunition loaded to about the same velocity and with the same weight of bullet because otherwise the trajectory will be skewed, but if you use 77gr and practice with 40gr it’s still not the end of the world.
Every round downrange is one more repetition with the weapon and one more chance to practice trigger control and follow through, and as long as you get a good group SOMEWHERE on the target you’re doing just fine. Just keep in mind that cone of uncertainty and the difference in trajectories.
So, in answer to your question, “it’s cheaper and it doesn’t have any ill effects.” Practice is practice, and more is always better.
Hornaday has recently introduced a line of ammunition they call their “Steel Match” ammo, which has all the consistency of their normal ammo combined with the cost savings of steel cased ammo and costs only slightly more than Wolf. I haven’t tested it out yet but it seems like the perfect practice ammunition, cheap AND consistent.
If you have a topic you want to see covered in a future “Ask Foghorn” segment, email guntruth@me.com.