First the disclaimer: Small sample sizes by themselves shouldn’t be relied upon for critical decisions. But when the results are significantly different enough, we can at least use them for the start of an evaluation.

The three groups pictured below were fired in succession from a bench rest with a JP Precision JP-15 AR with 18 inch barrel, 1/8" rifling, and chambered for 223 Wylde. The scopesight was a Leupold Mark 5HD 3.6-18×44mm, magnification set to 18×. Distance was 100 yards with nearly calm wind.

Five shots of Hornady 223 Remington 75 grain BTHP Match. The group measured 0.551 inch center to center (at 0.526 MOA my best group of the day).



On the left 10 shots of Lake City M193 5.56mm NATO, and on the right 10 shots of Federal 223 Remington AE223. As bulk training ammunition the two loads are similar. When they were available, both types usually sold for the same price. Bullets for both loads are 55 grain full metal jacket. Although I haven’t done side by side velocity measurements of the two loads, I believe the AE223 may be somewhat slower than the M193, but not enough for me to have ever noticed any trajectory differences at my usual training distances.



I was actually surprised by how well the AE223 performed from the JP. With my other ARs, I usually expect something on the order of 2 inch groups at 100 yards, so even bulk training ammo can benefit from a high quality rifle. The M193 obviously performed much worse, even based on a sample size of one. So the point? Check your rifle and the ammunition you intend to rely on for yourself. I expected these two types to perform about the same and obviously was mistaken.

As a separate point, I fired 10-shot groups with the two bulk loads to be more certain that the results would provide valid evaluations, but that’s something that many people who test ammunition don’t bother with. Let’s assume, though, that I had fired only three shots, as is not uncommon in reports in the gun periodicals, and that by chance they were the three circled below. Those three went into a group measuring only a little over of a quarter of an inch. If those had been the ones reported in a review article, what conclusions would we might have drawn about the ammunition and/or rifle? That’s always something we should keep in mind whenever someone reports on shooting results.

Good post.


Three shot groups are not statistically significant.


Different rifles/barrels definitely have their preferences for ammo.


M193, the actual milsurp stuff from Lake City, has never proven very accurate for me in any rifle that I have tried it in.

Plenty good enough for 100-200 yards (although 3-4 MOA is marginal at 200). M193 has velocity and reliability going for it. Although some of that velocity comes with high pressure. I have only ever seen a blown primer lock up a gun when it was Lake City M193. The man who was shooting the gun that day was an exceptionally qualified and respected individual who had a long career with 5th Special Forces Group. He was not using substandard equipment. Just something to keep in mind when making ammo purchasing decisions.

I don't want to (and probably can't) do the math on how significant a 3 shot group is versus a 10 shot group. I do think it is highly unlikely that the circled three shots were three in row, so the strong likelihood is a three shot group will tell you what you need to know.

Of course 5 shots is better, and 10 shots better still. But in reality it may be unnecessary to shoot more than three to be statistically conclusive. I'll ask one of my better math educated sons if they can do it.

M193 is widely known not to be terribly accurate. My own tests mirror your results.

If you really want accuracy, try Federal AE 50-grain hollowpoint. It's harder to find than the 55-grain FMJ, but only a little more expensive, and it is twice as accurate, not even kidding.

quote:

Originally posted by honestlou:
I don't want to (and probably can't) do the math on how significant a 3 shot group is versus a 10 shot group.

Interesting point. Long ago the American Rifleman ran an article discussing the mathematics (statistics?) of how groups would grow with additional numbers. I.e., if a five-shot group measured X, for example, a 10-shot group could be expected to measure X + (or ×) some factor. That’s the only discussion I’ve ever seen of the question and often wondered whether it had some theoretical basis or was just an empirical observation. It was presented as the former, but I don’t know enough about such things.

If anyone can answer for certain it would be interesting to know.

quote:

Originally posted by sigfreund:

The group measured 0.551 inch center to center (at 0.526 MOA my best group of the day).

You missed the target Shoot dot drills!

quote:

Originally posted by offgrid:
You missed the target Shoot dot drills!

Doh!

Some rifles shoot FMJ ammo fairly well, at least for a few groups here and there. AE223 tends to show better accuracy than many other 55 FMJ loads, but it still is an inaccurate load. All of my DI uppers have produced a few sub-MOA 5-round groups with AE, at distances from 100 to 300 yards. And then the next 5-round group might be 2 or 3 MOA. There's no consistency, especially as distances and winds increase. My piston LWRC upper is 1.5 MOA at best with AE55, but really is a 2.5 to 3 MOA rifle with AE55.

I stock AE55 for close distance, high volume, training on paper -- for specific stages in a 2-rifle match. I no longer shoot AE55 in my DI rifles, as I find it a waste of valuable barrel life.

I know there are people who consider the 55 FMJ the greatest thing since sliced bread. Other than low price, I don't see the appeal.

You have to take inTo account that the military requirement was only 4MOA when the M193 was introduced. Further down the timeline, IIRC, the M193 is now supposed to be 2MOA....

So target ammo it is not.

But yes, everyone should see what your barrel likes before getting too much of any one type of ammo packed into the boonker.

quote:

Originally posted by MikeinNC:
You have to take inTo account that the military requirement was only 4MOA when the M193 was introduced. Further down the timeline, IIRC, the M193 is now supposed to be 2MOA....

So target ammo it is not.

But yes, everyone should see what your barrel likes before getting too much of any one type of ammo packed into the boonker.

It's a bit late in the 2020 game to anticipate testing ammo, and stocking the boonker with the good performers.

Testing a few groups from what we already have in the boonker and loading up magazines with the good stuff might be a more attainable goal.

quote:

Originally posted by honestlou:
I don't want to (and probably can't) do the math on how significant a 3 shot group is versus a 10 shot group. I do think it is highly unlikely that the circled three shots were three in row, so the strong likelihood is a three shot group will tell you what you need to know.

Of course 5 shots is better, and 10 shots better still. But in reality it may be unnecessary to shoot more than three to be statistically conclusive. I'll ask one of my better math educated sons if they can do it.

5 shots is enough to tell you something. 3 shots is little better than nothing. I probably could do the math, but it's been a while since I took stats.

quote:

Originally posted by MikeinNC:
You have to take inTo account that the military requirement was only 4MOA when the M193 was introduced.

For the past 100+ years, minimum accuracy requirements for the various US military service rifles with service ammo have only been ~4-5 MOA.

They're designed for hits on human-sized targets, not bullseye competitions.

quote:

Originally posted by offgrid:
You missed the target Shoot dot drills!

No, I didn’t: I hit the center of the target with all five shots.