The video focuses on measuring how different .223/5.56 projectile weights and AR-15 configurations affect muzzle velocity. The host references a previous barrel-length velocity test and now shifts to comparing twist rates and gas systems using the same barrel length. The primary rifles are a Springfield Saint with a 16-inch barrel, mid-length gas system, and 1:8 twist, and a Daniel Defense DDM4 V7 with a 16-inch barrel, mid-length gas system, and 1:7 twist. Later, a Stag Arms LEO model with a 16-inch barrel, carbine-length gas system, and 1:7 twist is added to compare gas system effects. Ammunition includes 55 grain, 62 grain PMC green tip, and 77 grain open tip match loads. A chronograph is used to record velocities, and a Shadow Systems pistol is briefly fired to confirm the chronograph is functioning correctly before the main tests begin.
The first main test uses 55 grain .223/5.56 ammunition in the Daniel Defense DDM4 V7. Ten shots are fired, producing velocities mostly in the high 2800s to just under 3000 feet per second, with individual readings such as 2,994, 2,871, 2,912, 2,986, 2,940, and 2,973 feet per second. The Springfield Saint then fires ten rounds of the same 55 grain load, with velocities again clustering in the high 2800s to mid-2900s. After averaging ten shots from each rifle, the DDM4 V7 with its 1:7 twist and mid-length gas system records an average of 2,955 feet per second. The Springfield Saint with its 1:8 twist and mid-length gas system averages 2,939 feet per second. The roughly 16 feet per second advantage for the faster 1:7 twist is noted as real but practically negligible for most ballistic applications.
The test moves to 62 grain PMC green tip ammunition to see how a heavier projectile behaves in the same rifles. In the DDM4 V7, ten shots show more variation than expected, with velocities including 2,958, 2,949, 2,849, 2,910, 2,955, and several in the high 2800s to high 2900s. The average for the 62 grain load in the DDM4 V7 comes out to 2,918 feet per second. The Springfield Saint then fires ten rounds of the same 62 grain green tip. Its velocities appear slightly more consistent, with readings such as 2,941, 2,881, 2,838, 2,839, 2,899, 2,833, 2,970, 2,936, 2,935, and 2,982 feet per second. The Saint’s average is 2,900 feet per second. Both rifles show the expected drop in velocity compared to 55 grain, with roughly a 40 feet per second decrease, but the difference between the 1:7 and 1:8 twist remains small.
The final projectile weight tested is a 77 grain open tip match load. In the Daniel Defense DDM4 V7, the first shot records 2,358 feet per second, confirming a substantial drop compared to 55 and 62 grain loads. Subsequent shots include 2,390, 2,475, 2,473, 2,483, 2,494, 2,374, 2,461, 2,388, and 2,379 feet per second. The average for the 77 grain load in the DDM4 V7 is 2,425 feet per second. The Springfield Saint then fires the same 77 grain ammunition. Its velocities are unexpectedly higher overall, with readings such as 2,548, 2,402, 2,321, approximately 2,555, 2,489, around 2,495, 2,494, 2,484, 2,475, and 2,325 feet per second. The Saint averages 2,453 feet per second, making the 1:8 twist rifle slightly faster than the 1:7 twist DDM4 V7 with this heavy bullet, contrary to the earlier pattern and the host’s expectations.
To explore gas system effects, the video compares the Daniel Defense DDM4 V7’s mid-length gas system to a Stag Arms LEO model with a carbine-length gas system. Both rifles have 16-inch barrels and 1:7 twist rates. The 62 grain PMC green tip load is used for this segment. The DDM4 V7’s earlier average with this ammunition is 2,918 feet per second. The Stag Arms carbine then fires ten rounds, producing velocities such as 2,878, 2,964, 2,956, 2,938, 2,964, 2,949, 2,919, 2,954, approximately 2,999, and 2,928 feet per second. These results cluster tightly in the high 2800s to high 2900s. After averaging, the Stag’s carbine-length system yields 2,938 feet per second, about 20 feet per second faster than the mid-length DDM4 V7, contradicting the initial assumption that earlier gas bleed-off in a carbine system would reduce velocity.
The collected data shows that bullet weight has the most obvious impact on velocity: 55 grain loads are fastest, 62 grain loads are moderately slower, and 77 grain open tip match is significantly slower, especially when dropping from roughly 2,900 to the mid-2400 feet per second range. Differences between 1:7 and 1:8 twist rates and between mid-length and carbine gas systems are measurable but small, often around 15 to 20 feet per second. Some results defy the host’s expectations, such as the 1:8 twist Springfield Saint being slightly faster than the 1:7 twist DDM4 V7 with 77 grain ammunition, and the carbine-length Stag Arms rifle edging out the mid-length DDM4 V7 with 62 grain green tip. The video closes by suggesting future tests using barrels from a single manufacturer with controlled variables to isolate how barrel make, twist, and gas system individually influence velocity.
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