Is a 24" barrel worlds better than a 20"?

>>34430448
google knows

>>34430448
http://www.ballisticsbytheinch.com/calibers.html
http://forum.pafoa.org/showthread.php?t=158039

what the hell's up with the capchas?

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>>34430501
/pol/ probably found something and it is being used to filter posts

I googled it. Its a small diff. Like 2800fps vs 2900, or about 4% faster.

>>34430448

Depends entirely on the round, usually not worth it.

.308 loses about 20fps per inch

barrels on long arms should always be, at minimun, the length needed to fully burn the powder.

unless you have a need for a shorter weapon.

>>34430926

5.56 would need at least 28 inches, and most people think 20 is just fine

>>34430926
The problem with that statement is that handloads complicate the matter, and many people want shorter weapons for weight savings alone.

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>>34430945
ah, let me restate.

barrel length should be for maximum velocity. 20 inches is fine for standard us military 5.56RFNato.

>>34431001

Fair enough, I agree. If you aren't building a meme-room clearing gun or something for home defense than shorter barrels are pointless.

>>34430752
This. It's all about the pressure curve of your cartridge and powder. Incidentally, that's part of why blackpowder arm's were so long - you NEEDED the extra barrel length to fully use the slow-burning powder.

The specifics are well beyond me, mind you. Never could wrap my head around all the math of reloading.

>>34430448
Depends.

For the most part you get more velocity for barrel length, but some rounds will burn all their powder and start slowing down. M855 for instance is optimized for a 20" barrel, while most people wouldn't for below 24" for a 6.5 creedmoor. You choose a cartridge and barrel length by a rifle's intended use.

>>34431001
That's a graph of the M855 from this article:
http://www.sadefensejournal.com/wp/?p=1093

As it points out in the caption the M855 was designed for a 20" barrel. Most .223 and 5.56 round will benefit from extra length, but you start to get diminishing returns.

>>34431001
Why does the speed drop off at 21 and then rise up again?

>>34433178
Friction overcoming the pressure of the gas would be my guess.

>>34430448
No, the difference in velocity is not enough to matter.

From what I got, 20in best for intermediate cartridges, 24in minimum for AR10 cartridges, 30 inches minimum for anything close to .50 Cal and above. 16in and below for CQC, 18in if you can't decide between 16 and 20.

>>34433266
Wrong. 34 inches is where pistol barrels should start, PDW's should start at 38, intermediate cartridge rifels at 44 and full sized rifles at 50.

>but muh ur trolling

You'll come back crying when your military will start loosing battle after battle because your enemy outreached you with his bayonets.