.300 Blackout Velocity by Barrel Length

Velocity by barrel length for .300 Blackout (also known as ".300 BLK" (SAAMI) or ".300 AAC Blackout" (C.I.P.) - From MrGunsnGear on YouTube. We'll also briefly discuss best barrel length for something like an AR-15 pistol, below to allow you to better navigate various typical barrel length offerings.

Barrel Length	110 gr. (Velocity)	110 gr. (Energy)	125 gr. (Velocity)	125 gr. (Energy)	150 gr. (Velocity)	150 gr. (Energy)	220 gr. (Velocity)	220 gr. (Energy)
16"	2412 fps	1421 ft lbs	2221 fps	1339 ft lbs	1854 fps	1154 ft lbs	1102 fps	593 ft lbs
12.5"	2289 fps	1280 ft lbs	2118 fps	1245 ft lbs	1789 fps	1066 ft lbs	1027 fps	515 ft lbs
10.3"	2203 fps	1185 ft lbs	1984 fps	1094 ft lbs	1709 fps	973 ft lbs	960 fps	450 ft lbs
9"	2167 fps	1147 ft lbs	1975 fps	1090 ft lbs	1661 fps	919 ft lbs	957 fps	447 ft lbs
7.5"	2118 fps	1096 ft lbs	1957 fps	1063 ft lbs	1709 fps	973 ft lbs	953 fps	444 ft lbs

Best Barrel Length For .300 Blackout

For Subsonic Loads

Based on the data above, it appears that for subsonic loads such as 220 grain (where the .300 BLK really shines), barrel length can be an afterthought, particularly if you plan on using a suppressor. Something like a 7.5" barrel with an appropriate 7 to 8 inch suppressor would allow for a package that is still shorter and a little handier than a typical 16" barrel setup. Keep in mind that many manufacturers will not warranty their suppressors on barrels shorter than around 7.5 inches. This would still make a handy setup for military and law enforcement applications, as well as home defense or just a fun recreational setup for novelty.

For Maximum Velocity

If one were so inclined to use their .300 AAC Blackout setup as a full barrel length "AK replacement" in an AR-15 platform and without a suppressor, a 16" barrel will of course give you the most velocity out of any load, and more energy out of subsonic loads as well. Of course, adding a suppressor to that setup would give you a functional barrel length of over 22", which is not particularly handy. This could be acceptable for 5.56 but not as justifiable in a shorter range .300 Blackout rifle. Also, with the added length of the suppressor, some subsonic loads might break the sound barrier, so this is also something to consider beforehand.

Best Overall Barrel Length for .300 Blackout

The major question still comes down to whether you plan on using a silencer or not. If strictly looking for quietest and best handling setup, one could easily go as short as 5.5" which is offered by a number of manufacturers. Remember, a 7 to 8 inch suppressor will add velocity and make up for such a short barrel, but not fully. Overall a good compromise would be a barrel in the 7" to 9" range, which will offer an overall barrel length of about 14 to 16", granting solid muzzle velocity with all loads, handling that is slightly better or similar to a typical 16" carbine setup, and has the benefit of having a suppressor attached. 7.5" would probably be your best bet overall with a suppressor, especially since this is the minimum warranty barrel length for most suppressor manufacturers. If you want maximum velocity with a barrel still shorter than the norm and don't plan on using a suppressor, 12.5" is a great choice for a pistol style setup. And even if you opted to add one, you're still around (or just under) 20 inch barrel length, which isn't terribly excessive. Another thing to note is that shorter and thicker suppressors are out there, such as the Brevis II line from Delta P (5.5 inches long). This would allow a 12.5" barrel to make much more sense, but suppressors like that are not cheap.

Other Information

• Velocity by Barrel Length of Various Calibers
• 5.56x45mm NATO
• .277 Wolverine
• .300 Blackout
• .300 HAM'R

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