Range Report: Speer LE 75 Grain Gold Dot
Speer LE 75 Grain Gold Dot
Following in the footsteps of their successful 62/64 grain Gold Dot LE 223 Remington ammunition, Speer has introduced a 75 grain version of their blind-to-barriers “bonded” soft-point ammunition (#24475).
This ammunition is loaded in nickel-plated brass cases with crimped and sealed primers, however, there is no sealant at the case mouth. The load is charged with “ball” powder. The head-stamp reads:
“SPEER 15 223 REM”.
The form of the 75 grain Gold Dot is just what you would expect it to be; a longer and heavier version of the 62/64 grain Gold Dots.
Left to right: 1) 62 grain Fusion, 2) 62 grain Gold Dot, 3) 64 grain Gold Dot, 4) 75 grain Gold Dot.
Accuracy
I conducted an accuracy (technically, precision) evaluation of the Speer LE 75 grain Gold Dot ammunition 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 Competition Series 45x45mm scope adjusted to be parallax-free at 100 yards. A mirage shield was attached to the objective-bell of the scope. 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 accuracy evaluation was one of my semi-automatic precision AR-15s with a 24” Krieger barrel. The barrel has a 5.56mm Match chamber with a 1:7.7” twist. Prior to firing the 75 grain Gold Dot ammunition, I fired a 10-shot control group using match-grade hand-loads topped with the Sierra 55 grain BlitzKing. That group had an extreme spread of 0.62”.
Three 10-shot groups of the Speer LE 75 grain Gold Dot ammunition were fired in a row with the resulting extreme spreads:
1.12”
1.03”
1.05”
for a 10-shot group average extreme spread of 1.07”. The three 10-shot groups were over-layed on each other using RSI Shooting Lab to form a 30-shot composite group. The mean radius for the 30-shot composite group was 0.32”.
The smallest 10-shot group . . .
The 30-shot composite group . . .
Velocity
I chronographed the Speer LE 75 grain Gold Dot ammunition from a semi-automatic AR-15 with a chrome-lined, NATO chambered, 20” Colt M16A2 barrel.
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 a difference, the chronograph “flags” the shot to let you know that the data is invalid. There was no invalid data flagged during this testing.
The velocity stated below is the muzzle velocity as calculated from the instrumental velocity using Oehler’s Ballistic Explorer software program. The 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: 75 degrees F
Humidity: 33%
Barometric pressure: 30.05 inches of Hg
Elevation: 950 feet above sea level
The muzzle velocity for the 10-shot string of the Speer LE 75 grain Gold Dot ammunition fired from the 20” Colt barrel was 2652 FPS with a standard deviation of 11 FPS and a coefficient of variation of 0.42%.
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Last edited by Molon; 05-23-16 at 22:44.
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