Range Reports

Shooting Accuracy: The 100-Round Group

FIv shot group showing a single ragged hole in the green target

I have often stated that the absolute measure of accuracy is zero. All deviations are a detriment. That being said, the traditional three-shot group fired at 100 yards doesn’t always mean that much. Several events have occurred recently that spurred my interest in accuracy and prompted me to strive to understand it.

bullet holes in a diamond shaped target
This isn’t a one-hole group, but it is excellent by any standard.

One prompt is the result of research, the other practical application. I was reading about a spectacular and well-documented group of a mere .721 inch from the early days of benchrest, fired with a blackpowder rifle. The practical observation involved watching Woody Smith fire a single shot at each bullseye on a benchrest target.

Both are well beyond my own capabilities. I have come to feel that while the three-shot group is interesting, it is also a minimum. A 10-shot group might make more sense, but it is but little better than the three-shot group. I began to wonder if a 50- or 100-round group might make more sense.


Sale ends July 21, 2019


Sale ends July 21, 2019


After all, consider the varmint hunter who may fire 100 rounds or more at coyotes or other pests. He wants a rifle that is accurate and remains accurate despite powder or copper fouling.

I am all for cleaning the rifle and maintaining my gear. But a military sniper or varmint hunter is going to fire and fire again without cleaning. We need to know what the rifle will do in such a situation.

Firing three rounds, running a patch through the bore, letting the rifle cool, then firing again began to look pretty minimal. On the other hand, burnouts mean nothing. Firing 1,000 rounds as quickly as possible simply heats up the rifle and may warp the barrel. No need for that unless you are testing a new LMG for military service.

Two boxes and several loose rounds of Hornady match ammunition
Hornady Match ammunition gave good results.

Climbing the logic ladder, reason tells us that the three-shot group eliminates human error more so than a 20-shot group may. We may hold for three shots, while after a time holding the rifle becomes more of a chore—but then that is part of the test. We will pause, reload, and then reposition the rifle.

I began to guess that some rifles that did not do as well with three-shot groups might be more accurate in the long run, for several reasons. The very small groups and larger-than-average groups will be factored out of the more comprehensive firing session with 50 to 100 shots.

I elected to fire for accuracy with three of my favorite rifles, rifles I am familiar with and that are proven accurate. I would measure the groups at 10, 50 and 100 rounds.

You do not have to ask me twice to go to the range, but just the same, this is the type of repetitive shooting that demands discipline. I felt that my growth as a rifleman would benefit from this test and also that this amount of ammunition would be meaningful in testing each rifle’s potential. But neither would this amount of ammunition be harmful.

Wind and weather cooperated during the test, or the results may have been less valid. Just the same, every variable cannot be taken into account.

Cardboard target with five bullet holes
The more rounds you fire, the more you are likely to have some drift off center.

Rifles and Ammunition

The first rifle was my go-to rifle for alarms and excursions (an unlikely event these days). The Colt LEO 16-inch-barrel carbine is topped with a Redfield Battlezone optic. The magazines used were Magpul.

I elected to use a single loading, the Hornady 60-grain A-MAX. This loading has exhibited an average 1-inch three-shot group at a long 100 yards on many occasions. Occasionally, the groups have been smaller, but five-shot groups have been slightly larger as well.

The second rifle fired was a Savage Apex Storm with stainless steel 24-inch barrel and Vortex 3x9x40mm optic. I used the Hornady 140-grain Match ELD at 2,780 fps in this rifle. This rifle and cartridge combination has demonstrated groups of .85- to 1.25 inch in this accurate rifle.

The AR-15 was easier to use and fire due to its higher capacity, making 30 shots at a setting possible, along with its nice trigger, good ergonomics, and modest recoil. The Savage was not tiresome to fire, and the superb 3-pound Accurate Trigger was an advantage.

Box of Hornady 6.5 Creedmoor ammunition
The 6.5 Creedmoor is a joy to use and fire. Hornady loads are very accurate.

The third rifle is an Arsenal 7.62x39mm underfolder. I used the famous waffle-type magazine and Hornady’s 7.62x39mm ammo. The ammo was the last of a few boxes of 50 rounds I had on hand. Hornady Black is now offered in this caliber.

Test Procedure

I began with the Colt. This is a firearm marked by long familiarity and spotless service for more than a decade. I settled into a solid benchrest firing position and began the test. The initial three-shot group was 1 inch. I fired again, firing seven cartridges slowly and carefully, and the group opened to 1.15 inches. No notable increase was experienced until the end of 30 rounds. The group was now measured at 2 inches.

For a number of rounds the bullets simply disappeared into the black center. At 50 rounds, the group was 2.5 inches, but it would have been 2 inches without a couple of flyers that were probably the shooter’s fault. The next 50 rounds were pretty boring but meaningful. The final spread was 3 inches.

I took time to let the rifle cool but little between the four magazines used. The rifle demonstrated excellent practical accuracy. At any point during the test, the Colt could be counted on to put its shots within 1.5 inches of the point of aim. That is enough accuracy for any need I am likely to have.

Red box of Hornady 7.62x39mm SST ammunition
Hornady’s 7.62x39mm SST provided good accuracy.

The Savage is generally the more accurate rifle, but in this test the need to work the bolt might lead to less repeatability, I felt. I also have developed the habit of catching brass as it is ejecting and feeding it back into the cartridge box. I had to drop this habit or remain on the range all night and day.

The first group was .9 inch for three shots. As I fired, the rifle demonstrated excellent practical accuracy. At 10 rounds, the group was a mere 1 inch. At 25, 1.2 inches. At 50 rounds, the groups were 1.4 inch. By 75 rounds, I believe the barrel may have heated up, as there was some vertical stringing, increasing the group to 2.2 inches—still excellent by any standard. I ended up with a 100-round group of 3 inches. The Savage 6.5 Creedmoor is generally the more accurate of the two rifles, but in this case the AR exhibited more sustainable accuracy.

Firing the Arsenal underfolder with Hornady ammunition resulted in good groups at 50 yards—a change in range was undertaken since this is a fixed sight rifle.

a five-shot group showing a single ragged hole in the green target building to a 100-round group
One-hole groups are nice.

The initial three-shot groups to gauge the rifle’s accuracy were in the 1.5- to 1.7-inch range. As the 30-round magazine was emptied with care with the iron sights, I had more difficulty in aligning the sights, partly due to heat mirage perhaps. At 60 rounds, the group had opened to 2.5 inches. The final group was 3 inches at 50 yards for 50 rounds.

This was not a test firing as quickly as possible but a series of groups with each shot fired as accurately as possible. I think the end results accurately reflect the rifle’s accuracy potential. Most of you have fired rifles for accuracy and found mixed results. Some loads are more accurate than others. This is what handloading is all about—customizing a load to the rifle for maximum accuracy.

A sweet spot in accuracy is found by varying the bullet and powder, bullet weight, and even the overall length of the cartridge when possible. I have found that an accurate combination such as the Hornady Match load will seldom, if ever, be inaccurate in a given rifle. There are simply certain loads a rifle will prefer to the other. Poor performance is generally found with burner-grade ammunition, but that is another story.

Sometimes, inexpensive ammunition surprises with accuracy. A good rifle with good-quality ammunition may be tested thoroughly with this 100-round test, and the end result is a far better gauge of accuracy than the three-shot group.

Which rifle and ammunition combination have you been most impressed with? Have you ever fired a 100-round group for accuracy? How many shots do your fire in a single group to test a rifle? Share your answers in the comment section.

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Comments (5)

  1. Hunting rifles are sighted with clean, cold bores. One shot at a time. I have even gone so far as to sight my rifle after leaving it in case stuffed with blue ice to simulate the October/November chill. I can see where a larger sample size could certainly show some shooter errors that might not otherwise be apparent.
    But, probably not a good idea for the hunting rig. That just isnt how we shoot when we hunt.

  2. Because our indoor range is pistol only (for center-fire cartridges), .22 LR or Black Powder at 1/2 load for rifles, I don’t get the opportunity to fire my rifles as often as I’d like (nearest outdoor range is over an hour’s drive away). I do however reload my pistol ammunition for accuracy in my longer target shooting handguns. I’ve found that 5 shot groups give me the best results for checking the loads I’ve worked up. Whether in 6″ length barreled 9mm semi auto or 8 1/2″ barrel SAA in .357 magnum, the 5 shot group gives me better averages than longer string groups (I relate this to the strain of handgun v. rifle shooting, there is a difference). Longer strings, accuracy widen considerably, and is more likely due to my faults, not the gun or the ammo’s.
    I’ve not tried the experiment with rifles, but hope to see if I get similar results to what you’ve shown.

  3. Interesting waste of ammo. I’m much more I’m much more interested in whether a rifle will put its first shot from a cold bore in the same place every time. Seldom do I fire a 2nd shot at an animal. I can only recall shooting more than twice on 4 occasions. Two times involved a rifle that went wonky (broken scope on one and a stock that got wet and swelled on the other). The 3rd time was an elk and if I hit an animal that is still moving I shoot again. The 4th time involved body shots on a large boar hog when I was trying to learn whether a 223 is really enough cartridge for hogs.

    For ammo testing I use 3 shot groups initially. For fine tuning after the initial workup I use 5 shot groups. If I have two loads that are close I’ll shoot 10 shot groups. I could shoot a 100 shot group but out of a sporter weight bolt gun, it would take all day to tell me something meaningful if even then.

    Short of trying to evaluate a battle rifle, 100 shot groups are just something to write about.

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