9mm gain more advantage from long bbl than 40 or 45


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Dr_2_B
May 5, 2012, 06:49 PM
For the life of me, I can't find the post. But awhile back I recall reading that the 9mm benefits a great deal more from the length of a rifle barrel than a corresponding barrel length increase in, say, the 40 or 45.

Can anybody point me to that info?

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MachIVshooter
May 5, 2012, 11:21 PM
None of those gain much going from 4" or 5" to 16" or so. They all use fast powders. In my experience, .45 Auto gains the most.

Magnum-type cartridges with larger charges of slower powder benefit more from extra barrel length. 10mm Auto, .357 Mag., .44 Mag, etc.

TonyAngel
May 6, 2012, 01:33 AM
It's been a while, but from what I recall, the 9mm will pick up about a couple of hundred feet per second when coming out of a carbine length barrel as opposed the coming out of a 4 or 5" barrel. It isn't much, but it's something.

I would speculate that the 9mm and .40 cal would benefit more from being shot out of a longer barrel. I say this simply because these two cartridges are typically loaded with slower burning powder when max loads (or factory duplication loads) are used.

R.W.Dale
May 6, 2012, 01:55 AM
The greater pressure rating and and bore case ratio of 9mm/40 gives them a better ability to gain from more barrel than the very low pressure 45acp

56hawk
May 6, 2012, 10:25 AM
http://www.ballisticsbytheinch.com/mepngs/9mmluger.png
http://www.ballisticsbytheinch.com/mepngs/40sw.png
http://www.ballisticsbytheinch.com/mepngs/45auto.png

Pigoutultra
May 6, 2012, 01:11 PM
I guess smg's have it right with non I've seen having a barrel length of more than 10in.

Walkalong
May 6, 2012, 01:18 PM
It depends a lot on the powder. In general, fast powders will see little gain, and slower powders will show the most gain.

A Hornady 115 Gr RN over 6.3 Grs of HS-6 gave me 1039 FPS form a 3" EMP, 1168 FPS from a 5" 1911, and 1330 FPS from a 16" AR. (Check data and start low)

True Blue, AA #5, N340 etc give similar results, with N340 being the king of the 3" velocities.

N320, 700X, etc gave very little gains in the 16" barrel.

NMGonzo
May 6, 2012, 02:26 PM
Hit what you intend to.

Dr_2_B
May 8, 2012, 06:18 PM
Thanks 56Hawk. I find charts like those mesmerizing. I'll spend several minutes looking at those.

56hawk
May 8, 2012, 06:33 PM
Thanks 56Hawk. I find charts like those mesmerizing. I'll spend several minutes looking at those.

You're welcome. I got them from this site: http://www.ballisticsbytheinch.com/ They have the raw data and tests from specific firearms also.

MichaelK
May 8, 2012, 06:38 PM
I don't yet have data for .40S&W, but I've shot .38 specials in a 6" revolver and 16" carbine using 8 grains of Blue Dot. Blue Dot is definately over on the slow side of the burning curve and I got 1090 fps and 1265 fps respectively. That's only 175 fps from an extra foot of barrel. That's the same amount of Blue Dot I load with Lee's 120 TC in 9mm.

That data seems to correlate well with Lyman's data comparing pistol and carbine length barrels. For 9mm I believe you only got another 125 fps with a carbine barrel; nice, but not barn burning fast!

If you really want to see increased long-barrel performance, you need to go with larger revolver cases that can handle large amounts of H110.

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