Surplus Ammo Test Results (long)

[kotengu]

I conducted a sampling test of six different surplus .308 ammo types to find which one was suited best to my gun and skill level (or lack thereof). I conducted this test on Sept. 22, 2001 at Bend of The River Range in Cookeville, TN. The temperature started at 75 degrees and rose to 81 by the time I finished. The humidity was about 68%, and the sky was mostly clear. The range is 100 yds, and I was shooting from a bench and bags.

I was shooting an STG-58 kit I built on an Imbel receiver, with the bipod removed, and open sights. I cleaned the barrel and chamber after every nine shots (before I changed type of ammo). The rest of the gun was left un-cleaned and un-adjusted. I was single loading and shooting one wind condition (calm), so time between shots varied with the wind, but I always allowed at LEAST 15 minutes between ammo changes to allow the barrel to cool (it stayed warm to the touch, but not hot). I shot three, three shot groups for each type of ammo and measured group size and position of group (made a triangle from three shots and measured to middle of triangle), and calculated mean group size as well as position in relation to the bull (vector mean).

“HO” Headstamp - Singapore 1983
Group 1: 3.91” @ 12:15 by 1.50”
Group 2: 4.02” @ 7:00 by 2.50”
Group 3: 1.93” @ 6:30 by 3.35”
Mean Group Size: 3.29” with a standard deviation of 1.18”
Mean position: 6:45 by 1.46”

“HD” Headstamp - Singapore 1983
Group 1: 2.45” @ 7:30 by 3.60”
Group 2: 3.45” @ 7:00 by 2.10”
Group 3: 4.05” @ 7:30 by 2.10”
Mean Group Size: 3.32” with a standard deviation of 0.81”
Mean position: 7:20 by 2.60”

“* 79 * 7.62x51” Headstamp - Hirtenberger 1979
Group 1: 8.26” @ 9:00 by 1.25”
Group 2: 1.09” @ 5:30 by 3.30”
Group 3: 3.74” @ 5:30 by 5.80”
Mean Group Size: 4.36” with a standard deviation of 5.13”
Mean position: 5:50 by 2.92”

“FNM 2-81 (NATO cross)” - Portuguese 1981
Group 1: 4.00” @ 7:00 by 4.45”
Group 2: 4.40” @ 7:00 by 5.23”
Group 3: 3.65” @ 6:30 by 6.50”
Mean Group Size: 4.02” with a standard deviation of 0.38”
Mean position: 6:50 by 5.35”

“ P S 8 1” - maybe Czech, German, Spanish, or S. Korean 1981
Group 1: 3.87” @ 7:00 by 6.75”
Group 2: 3.65” @ 6:00 by 5.20”
Group 3: 3.73” @ 7:00 by 4.59”
Mean Group Size: 3.75” with a standard deviation of 0.11”
Mean position: 6:45 by 5.52”

“LC MATCH 71” US Match 1971
Group 1: 2.98” @ 7:30 by 1.6”
Group 2: 4.76” @ 6:00 by 3.55”
Group 3: 3.74” @ 5:30 by 4.00”
Mean Group Size: 3.83” with a standard deviation of 0.89”
Mean position: 6:00 by 2.85”

The results were not what I expected. Evidently, the match ammo did not make that much difference in this gun and with my (lack of) skill. The best group sizes came from the “HD” headstamped Singapore ammo, but the most consistent group sizes came from the “FNM” stuff. I only charted the positions out of curiosity to see how the impact points varied from different ammo sources - sights can be adjusted easily enough to account for that.

Sorry for the length, but it was an interesting study that I'll have to repeat when I finish my L1A1 kit.....

Matt

[DC]

thanks for the report. I wonder why the Hirt was so inconsistent.

[kotengu]

Dunno about the Hirt - it was interesting that I shot my best group with it, but I also shot my WORST group with it. I do think the barrel temp probably affected the groupings a little, but I was too impatient to wait 30 minutes in between each shot :)

I also think the groups would be smaller if I scoped it - but I don't normally shoot with a scope, so I wanted to see what iron sights would do.

[Doc AV]

Interesting spread of ammo.You have a mixture of two different primer types(boxer and berdan) and two different Boxer Flash-hole diameters (HP uses a smaller hole than the standard US/Korean/Israeli versions)

BTW, the PS 81 ammo is Poongsan Corp, ROK.
(PS Sevilla, Spain, for 7,62x51 has the H/S
SB-S and PS Czech did not make 7,62x51; I doubt it is still in operation)

Whilst not statistically accurate, your tests do show one thing, that variables will influence accuracy and group size.
You are right, though that FNM is the most consistent, and therefore the most reliable.

Regards, Doc AV

[usmc326]

If you had chronographed each type you would have found that the Portuguese FNM also has the lowest deviation in velocity, an average of about 16 fps,
which also contributes to consistent accuracy.
SOF magazine tested it a few years ago, and said it was the only surplus .308 that is as consistent, or better,
than Match ammo.
I don't think that waiting 30 mins. would've accomplished much, as all too many times the first shot out of a cold barrel becomes the one "flyer" of an otherwise good group.
Alot of good work that you put in. We are obviously grateful.

[kotengu]

I was just looking at my results again and I noticed I overlooked the PS81 - which turned out to be South Korean - as having a remarkably low standard deviation (about 1/3 of the FNM), with better group sizes than the FNM. Too bad I've never seen it before and bought it on a whim as an "un-identifiable" last package at the gun shop - has anybody seen any of this out there for sale?

[70 SS 454]

I dont understand all of this data

can someone explain
"Mean position: 6:50 by 5.35"
i understand what 6:00 or 8:00 etc would be but what does the :50 mean?

also what does the 5.35 mean..is that center of group to center of bulls eye?if so does that imply the fnm is significantly lower velocity causing it to "fall" that much more than the others?

or are factors other than velocity involved in where a bullet impacts vertically vs point of hold?

[ November 04, 2001: Message edited by: 70 SS 454 ]

[BUFF]

I can answer one of your questions. Oddly enough, ammunition shooting the same weight bullet at the same velocity from one gun will not always group to the same point of impact.

I have a Remington Model 700 .30-06, the first real gun I owned. I learned to handload on it. In college, it was not unusual to shoot 2,000 rounds a year from it. just about all were handloads. My standard deer load was a 150 grain spitzer at 2,900 fps, which I could get with several different hunting bullets and several different powders, ranging from medium-burning (relative to each other) to slow-burners like IMR-4350 and H-4198 (this was 25 years ago! Things have changed a bit!). I had a chronograph. I worked up 10 different loads to that velocity. All would group 5 shots into less than 3" at 100 yards from a rest. The best loads' groups averaged 1-1/4". If I shot ten 5-round groups, one 5 round group with each load (which I did several times as an experiment), on the same target, I ended up with a group over a foot in diameter! Of course, the big group was made up of ten little groups, some hitting several inches apart.

I then shot the same ten loads in 5 round groups from a buddy's Browning BAR, and got a 24 inch group!

I think it has to do with the different rates the powders burn at, the resulting different pressure curves, the different amounts of ejecta (the weight of the burned powder and resulting gasses, weight of the bullet, weight of the priming compound leaving the gun with the powder gasses), etc.) varying, and the different barrel harmonics they each produced.

Even with similar bullet weights and similar bullet velocities of the milsurp 7.62 ammo we can buy now, it is not at all surprising to have a point of impact difference of several inches between loads. The point of impact difference (higher or lower, left or right) can't be predicted from the cartridges' velocities. The fastest one won't always be the highest.

Man, I get wordy when I am tired and relive my youth!

[farranger]

SS 454, I believe what he means when he says for example "6:00 by 5.20" is that his bullets were impacting the target at 6:00 to point of aim and that they were 5.2 inches below point of aim. If I"m wrong someone please correct me. Kyle

[farranger]

great job Kotengu, forgot to say that in previous post.

[kotengu]

farranger got it right. I was using vector co-ordinites to document where POI was in relation to POA, but used the "o'clock" system instead of the degree system to measure the angle, and really only guessed at it. 6:50 just means not quite 7:00, and 5.35" means that was the distance from the bullseye (POA) to the middle of the group, found by drawing lines between the holes and finding the center of the triangle (POI).

As I said above - it's far from a "real" statistical analysis, but I learned a lot from it and will definitely repeat the process on my L1A1.

[marko16]

I concur with the Hirt ammo. Just when I get rid of it and think Radway is better, it will out shoot it, then it all goes bad and shoots bad.

[MK ULTRA]

I would check for something loose. I've never seen an 8" group from a FAL. My AK and SKS do better.

I'm not knocing you. I think something is wrong somewhere. How tight did you get the barrel in the receiver?? If you get the barrel too tight it will hurt your accuracy. I always try to hand tighten it to 11:00 with anti seeze on it and go on with the wrench.

good luck next time........

MK ULTRA.....OUT....... :D :D :D