Rifle Caliber Pistols and SBRs, many questions

[Ananael]

I was reading the PCC thread, and I wanted to know the opposite: With all the AR pistols and SBRs/PDWs coming out on the market these days, how do the rifle calibers do out of such short barrels?

I've heard that 6.8spc was developed to address losses in effectiveness of 5.56 out of shorter barrels, is this true? What about 7.62/.308?

Basically, are you still getting rifle level ballistics when you shoot these calibers out of shorter barrels from 8-14"?

I'm a total newb to rifles, so if there's an obvious site on which to find this info, maybe something like the rifle version of Ballistics By The Inch, just let me know!

Thanks all!

[DefensiveCarry.com]

[jwhite75]

I think the Rifle caliber pistols are an awesome way to get a SBR without the ATF run around. I would definitely like to have one. KAC is making their PDW in a pistol now...I would love one of those in 6.8 or 5.56

[Ring]

the FPS drops quite a bit over a full sized rifle, but even at that speed, with the right ammo, it would make a great HD gun, but the flash and muzel blast would be bad... if you had a suppressor, it would be awsum..

[HotGuns]

Basically, are you still getting rifle level ballistics when you shoot these calibers out of shorter barrels from 8-14"?

Up to a point.
The idea is to have a quick handling rifle in close quarters. There is enough energy to kill an enemy in an efficient manner.

They are OK up to a point. At extended ranges their performance falls off drastically, which isn't that big of a deal really because at extended ranges you would be using a SBR anyway.

Even the M-4 with its 14" barrel that is in wide use over in the Mid East has been seen as somewhat lacking at ranges over 300 yards. That extra few inches of barrel makes a difference.