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

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Dr_2_B

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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?
 
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.
 
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.
 
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
 
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.
 
Thanks 56Hawk. I find charts like those mesmerizing. I'll spend several minutes looking at those.
 
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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