Underpowered ammo velocities?

[Giggles]

What velocities would be considered underpowered when it comes to .223 / 5.56?

[Clint]

Velocity and port pressure are not directly related.
The powder burn rate can affect cycling greatly.

[markm]

Velocity and port pressure are not directly related.
The powder burn rate can affect cycling greatly.

Exactly. Bullet weight and powder burn rate can be combined/tuned to various levels.

[T2C]

Velocity and port pressure are not directly related.
The powder burn rate can affect cycling greatly.

Thank you. A lot of people do not understand that.

[TomMcC]

Thank you. A lot of people do not understand that.

I still have a bit of English Radway Green SS109 they dumped on the surplus market some years ago. It only works in my carbine length rifle, but not my rifle length rifle. Burn rate was not optimize to run across the board on barrel lengths, but then they weren't making it for the American AR series.

[T2C]

I still have a bit of English Radway Green SS109 they dumped on the surplus market some years ago. It only works in my carbine length rifle, but not my rifle length rifle. Burn rate was not optimize to run across the board on barrel lengths, but then they weren't making it for the American AR series.

We used Radway Green for shooting High Power Rifle matches when shooting at reduced distances. It shot well enough through my RRA match rifle to score plenty of X's on a MR-31 at 100 yards.

[TomMcC]

We used Radway Green for shooting High Power Rifle matches when shooting at reduced distances. It shot well enough through my RRA match rifle to score plenty of X's on a MR-31 at 100 yards.

Weird, I wonder if they're different vintages. Yours worked in a 20 and mine works in a 14.5.

[davidjinks]

Do you mean “Underpowered” in regards to affects on target? I.E. it lacks penetration, fragmentation, expansion etc...

What velocities would be considered underpowered when it comes to .223 / 5.56?

[Giggles]

I’m asking in reference to internal ballistics not terminal ballistics. I was just wondering after I observed a tuned gun fail to lock back a bolt while firing PMC bronze, and it made me wonder if that ammo is considered “underpowered” especially it’s posted velocity on the box is like 2900 FPS.

[davidjinks]

To answer that you would need to find out the minimum velocity threshold of the particular projectile you are using.

An example would be; Speer Gold Dot 5.56MM 75 grain will penetrate and expand at a minimum of 1800 FPS. I made those numbers up because I don’t use that type of projectile/ammo.

I’m asking in reference to internal ballistics not terminal ballistics. I was just wondering after I observed a tuned gun fail to lock back a bolt while firing PMC bronze, and it made me wonder if that ammo is considered “underpowered” especially it’s posted velocity on the box is like 2900 FPS.