IMI M193 Accuracy Over A Span Of 15 Years
IMI M193 Accuracy Over A Span Of 15 Years
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I started shooting M193 ammunition produced by Israel Military Industries (IMI) in the year 2000. At that point in time, IMI was still using their headstamp of TZZ. I first noticed the IMI headstamp on a 2002 lot of this ammunition.
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Unfortunately, much of my early test data for IMI M193 was lost due to a tragic boating accident (hard drive crash actually), so the accuracy/precision data for this article will start with a lot from 2006.
The 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" at 100 yards. All testing for this article was conducted at a distance of 100 yards (verified with a laser range finder).
The accuracy (technically, precision) evaluations of the IMI M193 ammunition were performed following my usual protocol. These accuracy evaluations 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, control groups were fired from each barrel used in the evaluations using match-grade hand-loads. As an example, the 10-shot group pictured below was fired from the 20 Lothar Walther barrel at a distance of 100 yards using a hand-load topped with the Sierra 52 grain MatchKing. The group has an extreme spread of 0.58 In all cases, the extreme spreads and mean radii of the control groups were significantly smaller than those of the ammunition being tested.
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All shooting was conducted from a concrete bench-rest from a distance of 100 yards The barrels used in the evaluations were free-floated. The free-float handguards of the rifles rested in a Sinclair Windage Benchrest, while the stock of the rifles 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.
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The Wind Probe . . .
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2006
The 2006 lot of IMI M193 was tested using a chrome lined, NATO chambered 20 Colt HBAR with 1:7 twist.
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The average extreme spread for three, 10-shot groups fired in a row was 2.48. The three, 10-shot groups were over-layed on each other using RSI Shooting Lab forming a 30-shot composite group. The mean radius for the 30-shot composite group was 0.72. The 30-shot composite group is pictured below.
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2007
The 2007 lot of IMI M193 was also tested using a chrome lined, NATO chambered 20 Colt HBAR with 1:7 twist. The average extreme spread for three, 10-shot groups fired in a row for this lot was 2.65. The 30-shot composite group had a mean radius of 0.94.
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2009
The 2009 lot of IMI M193 was tested using a chrome lined, NATO chambered 16 Colt HBAR with a 1:9 twist. This 2009 lot is the same lot that I tested for my 2010 article Attack of the M193 Clones.
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Three, 10-shot groups fired in a row had an average extreme spread of 2.80. The mean radius for the 30-shot composite group was 0.97.
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2011
The 2011 lot of IMI M193 was the most consistent lot of this ammunition that Ive tested. The barrel used to test this lot was a 20 Lothar Walther stainless steel barrel with a 223 Wylde chamber and a 1:8 twist.
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While it is sometimes possible to obtain slightly better accuracy from mil-spec/NATO pressure ammunition by firing it from an AR-15 that has a stainless steel match-grade barrel with a hybrid chamber, such as the Noveske Match Mod 0 chamber or a 223 Wylde chamber, you're not going to make a silk purse out of a sows ear doing this.
This lot of IMI M193 was so consistent in preliminary testing, that I decided to fire eight, 10-shot groups in a row for the formal evaluation. The average extreme spread for the eight, 10-shot groups was 2.07. All eight of the 10-shot groups were over-layed on each other to form an 80-shot composite group. The mean radius for that 80-shot composite group was 0.64.
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2021
Skipping ahead 10 years from the previous lot tested, the IMI M193 ammunition is still performing like it did with the previous lot. This lot was also tested using the 20 Lothar Walther stainless steel barrel with a 223 Wylde chamber and a 1:8 twist. The average extreme spread for three, 10-shot groups fired in a row was 2.31. The mean radius for the 30-shot composite group was 0.65.
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The grand average extreme spread for all 20 of the 10-shot groups tested for this article was 2.36. The grand mean radius for all 200 of the rounds fired for this article was 0.75.
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