Return Of The M193 Clones




clone:  one that appears to be a copy of an original form


Part 1

Genuine US Military M193 can no longer be sold to civilians, thanks to the Clinton Administration.  The ammunition that is sold on the commercial market with some form of “M193” in its nomenclature is often referred to as an “M193 clone” because it “appears to be a copy” of genuine M193, but we generally have no idea what specifications of MIL-C-9963 that this ammunition has passed, or has even been tested for.

Genuine M193 must be tested for and pass all of the specifications laid out in the mil-spec, MIL-C-9963.  The required areas of testing included in MIL-C-9963 range from velocity, accuracy, chamber pressure and port pressure to waterproofing, temperature stability, bullet extraction, case hardness, fouling and much more.  

M193 is loaded with a 55 grain FMJ bullet with a cannelure.  The bullet itself, must meet required specifications in order to be used in genuine M193 ammunition.  For example, the specification for the thickness of the gilding metal jacket of the bullet is 0.021" with a tolerance of - 0.002".    For comparison, the jacket of Hornady’s 55 grain FMJ bullet has a thickness of approximately 0.028”.  

Jacket thickness can have a significant effect on terminal ballistic properties, particularly that of fragmentation.  Even the composition of the copper alloy used for the jacket and the lead used for the slug must meet mil-spec requirements for genuine M193.

Genuine M193 can only be charged with powder that has been specifically approved by the US Military for use in this cartridge.  If the ammunition in question is not loaded with one of the approved powders, it is not genuine M193 and naturally we have no way of determining what powder was used in a load simply by visual inspection.

Genuine M193 will have the annealing iris visible on the shoulder and neck portion of the case.  It will also will have crimped and sealed primers. Genuine M193 has a crimped case mouth along with sealant at the case mouth.

In 2010, I posted an in-depth evaluation of four different brands of M193 clones that were readily available at that time.
(Attack of the (M193) Clones)

For this article, I evaluated recent production lots of the same four brands of M193 clones (though not necessarily the same manufacturers.)


Winchester M193



This lot of Winchester M193 is loaded in Lake City brass with a 2021 headstamp.  The case-head stamp exhibits the octal station identifiers found on Lake City SCAMP machinery.  The brass cases have the annealing iris still visible.  The rounds are charged with ball powder.

The primer pockets are crimped, but do not have any sealant.  The case mouths are also crimped, but also have no sealant.








The lot number for this lot of Winchester M193 is pictured below.  The “WLC21” in the prefix of the lot number indicates that this lot of Winchester M193 was manufactured at Lake City in 2021 under Winchester “management.”









Federal XM193




This lot of Federal XM193 is loaded in Lake City brass with a 2021 headstamp.  The case-head stamp exhibits the octal station identifiers found on Lake City SCAMP machinery.  The brass cases have the annealing iris still visible.  The rounds are charged with ball powder.

As with the Winchester M193, the primer pockets of this lot of Federal XM193 are crimped, but do not have any sealant.  The case mouths of this lot of Federal XM193 are also crimped, but also have no sealant.






The lot number for this lot of Federal XM193 is pictured below.  The “WLC21” in the prefix of the lot number indicates that this lot of Federal  XM193 was manufactured at Lake City in 2021 under Winchester “management.”






IMI M193




This lot of IMI M193 is loaded in IMI brass with a 2021 headstamp.  The annealing iris is visible and the rounds are charged with ball powder.  The primer pockets are crimped and sealed and the case mouths are also crimped and sealed.








Prvi Partizan (PPU) M193





The PPU M193 brass has a 2020 headstamp and the annealing iris is visible.  The primer pockets are crimped and sealed, as are the case mouths and the ammunition is charged with ball powder.

















Part 2

Aside from aspects of M193 clones that can be assessed by visual inspection, the two main aspects of M193 clones that we can assess via live fire testing to determine if an M193 clone adheres to the US mil-spec are velocity and accuracy (technically precision).  The velocity specification for M193 as cited in MIL-C-9963F states:

"The average velocity of the sample cartridges, conditioned at 72 degrees, plus or minus 2 degrees Fahrenheit (F), shall be 3165 feet per second (ft/sec), plus or minus 40 ft/sec, at 78 feet from the muzzle of the weapon.  The standard deviation of the velocities shall not exceed 40 ft/sec."

The velocity specification is for a 20” test barrel.  Depending on multiple variables, this velocity specification equates to a muzzle velocity of approximately 3270 ft/sec, plus or minus 40 ft/sec.

As an aside, after reading the above specification, some of you may be wondering, “Why 78 feet from the muzzle?”  The answer to that question is that this specification is simply an historical hold-over from the days when “circuit” chronographs (e.g. Le Boulenge Chronograph and the Aberdeen Chronograph) were used at Aberdeen Proving Ground, Frankford Arsenal and Springfield Armory.  These types of chronographs required a significant distance between their first and second screens to produce accurate results.

As an example, when using the Boulenge Chronograph, the first screen of the chronograph was placed 3 feet in front of the muzzle and the second screen was placed 150 feet beyond the first screen.  For those of you who might not be aware of the following fact; chronographs determine the velocity of the bullet at a point that is midway between the first and the second screen (i.e. not at the location of the first screen).  Therefore, with the above spacing, the velocity of the bullet is determined for a point that is 75 feet from the first screen.  So, add the three feet (from the muzzle to the first screen) to the 75 feet (the midway point of the screens) to obtain the “78 feet from the muzzle” distance.





I chronographed the four M193 clones evaluated for this article from a semi-automatic AR-15 with a chrome-lined, NATO chambered 20” Colt barrel with a 1:7” twist.

Chronographing was conducted using an Oehler 35-P chronograph with “proof screen” technology. The Oehler 35P chronograph is actually two chronographs in one package that takes two separate chronograph readings for each shot and then has its onboard computer analyze the data to determine if there is any statistically significant difference between the two readings.  If there is, the chronograph “flags” the shot to let you know that the data is invalid.  There was no invalid data flagged during this testing.

The velocities listed in the table below are muzzle velocities as calculated from the instrumental velocities using Oehler’s Ballistic Explorer software program. Each string of fire consisted of 10 rounds over the chronograph.









Each round was single-loaded and cycled into the chamber from a magazine fitted with a single-load follower. The bolt locked-back after each shot allowing the chamber to cool in between each shot. This technique was used to mitigate the possible influence of “chamber-soak” on velocity data. Each new shot was fired in a consistent manner after hitting the bolt release.  Atmospheric conditions were monitored and recorded using a Kestrel 4000 Pocket Weather Tracker.





Atmospheric conditions

Temperature:  72 degrees F
Humidity:  78%
Barometric pressure:  30.02 inches of Hg
Elevation:  950 feet above sea level


The muzzle velocities of the four M193 clones are listed in the table below, along with the standard deviations and coefficients of variation.





For those of you who might not be familiar with the coefficient of variation (CV), it is the standard deviation, divided by the mean (average) muzzle velocity and then multiplied by 100 and expressed as a percentage. It allows for the comparison of the uniformity of velocity between loads in different velocity spectrums; e.g. 77 grain loads running around 2,650 fps compared to 55 grain loads running around 3,250 fps.  

The mil-spec for M193 allows for a coefficient of variation of approximately 1.2%, while one of my best 77 grain OTM hand-loads, with a muzzle velocity of 2639 PFS and a standard deviation of 4 FPS, has a coefficient of variation of 0.15%.






For comparison to the velocities of the M193 clones evaluated for this article, the next table shows the muzzle velocities of the four M193 clones that I evaluated in 2010 (also fired from a 20” Colt barrel.)








Part 3

The US accuracy specification for M193 cited in MIL-C-9963F is as follows:

“The average of the mean radii of all targets of the sample cartridges, fired at 200 yards, shall not exceed 2.0 inches.”

These averages are from 10-shot groups fired from machine rested, bolt-actioned, heavy test barrels. All things being equal this specification equates to a mean radius of 1 inch at 100 yards (the distance at which I tested this ammunition).

I conducted an accuracy (technically, precision) evaluation of the four M193 clones following my usual protocol.  This accuracy evaluation used statistically significant shot-group sizes and every single shot in a fired group was included in the measurements. There was absolutely no use of any Group Reduction Techniques (e.g. fliers, target movement, Butterfly Shots).

The shooting set-up will be described in detail below. As many of the significant variables as was practicable were controlled for. Also, a control group was fired from the test-rifle used in the evaluation using match-grade, hand-loaded ammunition; in order to demonstrate the capability of the barrel. Pictures of shot-groups are posted for documentation.

All shooting was conducted from a concrete bench-rest from a distance of 100 yards (confirmed with a laser rangefinder.) The barrel used in the evaluation was free-floated. The free-float handguards of the rifle rested in a Sinclair Windage Benchrest, while the stock of the rifle rested in a Protektor bunny-ear rear bag. Sighting was accomplished via a Leupold VARI-X III set at 25X magnification and adjusted to be parallax-free at 100 yards. A mirage shade was used. Wind conditions on the shooting range were continuously monitored using a Wind Probe. The set-up was very similar to that pictured below.







The Wind Probe . . .





The test vehicle for this evaluation was one of my semi-automatic precision AR-15s with a 20” stainless-steel Lothar Walther barrel.  The barrel has a 223 Wylde chamber with a 1:8” twist.















Prior to firing the M193 clones, I fired a 10-shot control group using match-grade hand-loads topped with the Sierra 52 grain MatchKing.  That group had an extreme spread of 0.64”.







Prvi Partizan (PPU) M193

Three 10-shot groups of the PPU M193 ammunition fired consecutively from the Lothar Walther barreled AR-15 at a distance of 100 yards had the following extreme spreads:

3.00”

2.28”

3.48”

for a 10-shot group average extreme spread of 2.92”.  I over-layed the three 10-shot groups on each other using RSI Shooting Lab to form a 30-shot composite group.  The mean radius of the 30-shot composite group was 0.80”.

The smallest 10-shot group . . .




The 30-shot composite group . . .





Winchester M193

Three 10-shot groups of the Winchester M193 ammunition fired consecutively from the Lothar Walther barreled AR-15 at a distance of 100 yards had the following extreme spreads:

2.21”

2.65”

2.09”

for a 10-shot group average extreme spread of 2.32”.  I over-layed the three 10-shot groups on each other using RSI Shooting Lab to form a 30-shot composite group.  The mean radius of the 30-shot composite group was 0.72”.


The smallest 10-shot group . . .




The 30-shot composite group . . .





Federal XM193


Three 10-shot groups of the Federal XM193 ammunition fired consecutively from the Lothar Walther barreled AR-15 at a distance of 100 yards had the following extreme spreads:

2.36”

2.67”

1.77”

for a 10-shot group average extreme spread of 2.27”.  I over-layed the three 10-shot groups on each other using RSI Shooting Lab to form a 30-shot composite group.  The mean radius of the 30-shot composite group was 0.66”.


The smallest 10-shot group . . .




The 30-shot composite group . . .






IMI M193


Three 10-shot groups of the IMI M193 ammunition fired consecutively from the Lothar Walther barreled AR-15 at a distance of 100 yards had the following extreme spreads:

1.84”

2.86”

2.16”

for a 10-shot group average extreme spread of 2.29”.  I over-layed the three 10-shot groups on each other using RSI Shooting Lab to form a 30-shot composite group.  The mean radius of the 30-shot composite group was 0.64”.


The smallest 10-shot group . . .




The 30-shot composite group . . .





The table below summarizes the accuracy/precision results for this article.






For comparison, the next table summarizes the accuracy/precision results from the 2010 evaluation.








…..

A PRIMER ON THE MEAN RADIUS


The mean radius is a method of measurement of the radial dispersion of shot-groups that takes into account every shot in the group. It provides a more useful analysis of the consistency of ammunition and firearms than the commonly used method of extreme spread.

Mean radius as defined in Hatcher's Notebook “is the average distance of all the shots from the center of the group. It is usually about one third the group diameter (extreme spread)” for 10-shot groups. The ratio is actually closer to

3.2 x the mean radius = the extreme spread

for 10-shot groups, depending on the sample size and the morphology of the particular groups sampled.

To obtain the mean radius of a shot-group, measure the heights of all shots above the lowest shot in the group. Average these measurements. The result is the height of the center of the group above the lowest shot. Then in the same way, get the horizontal distance of the center from the shot farthest to the left. These two measurements will locate the group center. Now measure the distance of each shot from this center. The average of these measures is the mean radius.

Once you get the hang of measuring groups using the mean radius it becomes very simple to do. While being very simple to do, it is also very time consuming. Modern software programs such as RSI Shooting Lab and On Target make determining the mean radius a snap.

The picture below is a screen capture from RSI Shooting Lab. The red cross is the center of the group (a little high and right of the aiming point). The long red line shows the two shots forming the extreme spread or group size. The yellow line from the red cross to one of the shots is a radius. Measure all the radii and take the average to obtain the mean radius.




Mean Radius Demonstration


Let’s say you fired a 5-shot group from 100 yards and the resulting target looks like this. (The X-ring measures 1.5” and the 10-ring measures 3.5”.)






The extreme spread of the group measures 2.83”, but we want to find the mean radius (or average group radius.) In order to find the mean radius we must first find the center of the group. By “eye-balling” the target most people would see that the group is centered to the left of the “X-ring” and probably a little high, but we need to find the exact location of the center of the group.


Locating the Center of the Group

The first step in finding the center of the group is to find the lowest shot of the group and draw a horizontal line through the center of that shot.





Next, find the left-most shot of the group and draw a vertical line through the center of that shot.






Now measure the distance from the horizontal line to the other four shots of the group that are above that line. Add those numbers together and divide by the total number of shots in the group (5).






2.50” + 1.03” + 2.01” + 1.30” = 6.84”

Divide by 5 to get 1.37”. This number is the elevation component of the center of the group.

Next we need to find the windage component of the center of the group. From the vertical line, measure the distance to the other four shots of the group that are to the right of the line. Add those numbers together and again divide by the total number of shots in the group (5).










1.76” + 2.54” + 0.45” + 1.19” = 5.94”

Divide by 5 to get 1.19” This is the windage component of the center of the group.

Finding the windage and elevation components of the center of the group is the most difficult part of this process. Once that is done the rest of the process is a piece of cake.

Using the windage and elevation components, locate the position on the target that is 1.37” (elevation component) above the horizontal line and 1.19” (windage component) to the right of the vertical line. This location is the center of the group!









Determining the Mean Radius


Now that we have located the position of the center of the group, the first step in determining the mean radius is to measure the distance from the center of the group to the center of one of the shots. This line is a single “radius”.




Now measure the distance from the center of the group to the center of each of the rest of the shots in the group. Add the measurements of all the radii together and then divide by the total number of shots in the group (5).





0.85” + 1.35” + 1.38” + 0.84” + 1.61” = 6.03”

Divide by 5 to get 1.21”. This is the mean radius (or average group radius) of the group!

Using the mean radius measurement to scribe a circle around the center of the group gives you a graphic representation of the mean radius. This shows the average accuracy of all the shots in the group. This demonstrates why the mean radius is much more useful than the extreme spread in evaluating the radial dispersion of our rifles and ammunition.






The table below will give you an idea of the relationship between the mean radius and extreme spread for 10-shot groups.






Here are some interesting quotes on the subject from old issues of American Rifleman.

“Mean radius is the mean distance of bullet impacts from the center of the test group. It is used in government ammunition acceptance because it takes account of every shot and comes close to maximizing the test information. While there is no exact relationship between this measure and the simpler and more convenient group diameter, the 10-shot group diameter averages slightly over 3 times the mean radius.”

"These examples illustrate the sensitiveness of the extreme spread to number of shots in the group. Indeed, as the table indicates, the measures made to only the outside shots of the group, e.g. the extreme spread, are very sensitive to number of shots, while the measures made to all the shots, e.g. the mean radius are far less so. It may be added that the latter measures are also less variable in their representation of the group; they are more efficient. This explains why the target testing of U.S. military rifle ammunition is by mean radius."



…

In on historic Molon thread

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Awesome thread. Thanks Molon.

Nice work!

Love this! Great work molon. Can't wait for you to get around to the m855 clones.

I don't shoot my ARs a fraction of what I used to, but tagged anyway. GREAT thread.



In before sub-moa M193 claims.

Attached File

Time to neckbeard IMI.

What a time to be alive

In! Thank you for all your work and dedication.

Nice job.

OST!

Outstanding! Thanks for sharing.

I read every word.  Interesting, informative and entertaining.  10 out of 10.

Molon, I know you did a review of MEN 193 before, but was wondering why it was left off this review?

I’m so glad you’re still around. Thanks for teaching us all so much.

Can't thank you enough for providing this kind of data.

Over the years, it keeps me coming back to arfcom.

Attached File

Thanks for all the work!

_{... though my stash of M193 is a lot closer in age to your first report}

Tag

Subscribage

Molon,

Thank you for providing us with your posts.  The amount I learn in your posts is astonishing.

You are an asset to this forum.

great info. Thanks for taking the time to test and document your results.

So federal XM193 is the way to go?

Nice data, thanks!

hell yeah. thanks OP

in on 1

I always appreciate your detailed analysis.  Thank you for sharing. Would love to see if a slower twist such as 1/12 would make an improvement.

This article was an evaluation of the same four brands of M193 clones that I tested in 2010.  I didn't test any MEN M193 in 2010.

Damn, nice post.

As always, @Molon, thank you for all of your hard work and fact based data. You are an asset to this site.

Thank you for this very important information. BTW, the LC lot numbers also tell you the month of production via the letter after the year of production.
A= January
B= February
C= March

I'm sure that guy from the other day will be along to post a more informative article refuting your accuracy claims and showing us what that loading can really do.

Attached File


Attached File

thanks, great info

Cliff notes for the stupid?  I seriously don't have the time to read it, during this x-mas time.

Thank you Molon for still coming around. You're 2010 thread led me to stack the IMI 193 when I was still relatively new to the AR and it was still at stackable prices. I've also recommended it several to friends in the years since as they got into ARs.

I realize there is prohibition on sale to the civilian market... but can't a few stripper clips still find their way off a range to be cannibalized for examination?

Outfuckingstanding!!!

Glad to see you back posting here again.

What's up with IMI dropping 100 fps since your last eval? That's what I usually horde because it shoots so nicely in my rifles.

Thanks, Molon. Great post.

Cheap ammo 3 MOA
Expensive ammo 1 MOA
Cheap 1 MOA ammo is lie

Awesome!

Seems like the biggest change over time is that IMI is sort of neutered in velocity compared to what it once was.

@thatguywhoshoots1moawithM193

Thanks

Thanks for posting real stuff. Beans/no beans and tranny threads get old.
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Glorious. As usual.

Impressive, thanks!

Now try it again with a Del-Ton barrel...

Great work, as always! It's posts like this and the Ammo Oracle that originally got me hooked on this site.

Have you done any evaluations for newer calibers, such as .300 Blackout or 6.5 Grendel?