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Old March 5, 2013, 06:06 PM   #1
cajun47
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how much more speed a 9mm would have from 4" to 5" barrel?

glock 19 has about 4" barrel and beretta 92f has about 5" barrel.

what would be the speed difference if both shot 115 gr. gold dots and 147 gr. gold dots?
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Old March 5, 2013, 06:29 PM   #2
jmr40
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This is not perfect, every gun is different, but is as good a guess as any. According to this website around 50 fps. I've not chronographed 9mm from anything but my 4" G-19 so I don't have any direct comparison with 9mm.

http://www.ballisticsbytheinch.com/9luger.html

I have shot multiple barrel lengths in 44 mag and 357 mag handguns and several rifle calibers and have found their results with those calibers to be pretty accurate. Not perfect, but close

You also have to consder that each gun/barrel is different. It is not uncommon to see 50 or more fps difference between identical guns with identical barrel lengths firing ammo from the same box.
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Old March 5, 2013, 06:46 PM   #3
RBid
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From a Glock 19 to a Beretta 92FS, I'd expect a difference of about 30-35 fps. I would guess that the G19 makes about 15-20 fps more than a standard 4" barrel, due to polygonal barreling. Subtracting that from the estimated 50... 30-35.

Others may provide more clarity.
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Old March 6, 2013, 07:19 PM   #4
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If you're looking for maximum velocity from a 9mm you may get more benefit from a good +p or +P+ load like those offered by Cor Bon, Black Hills, or Buffalo Bore than you will from an extra inch of barrel. I carry Buffalo Bore 124g+P+ In my S+W M+P compact. It's accurate and still really controllable in that gun.
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Old March 6, 2013, 08:16 PM   #5
481
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Just my experience, but for every inch of barrel past 4", expect to see about 35 fps more velocity from the 9mm.

Of course, I also had a G19 (4") that'd shoot Fed 147 gr. HydraShoks 75 fps faster than my G17 (4.5"), but that just goes to show that there are no guarantees that a longer barrel will shoot faster than a shorter one.
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Old March 6, 2013, 08:27 PM   #6
bamaranger
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G17 v. G34

I just screened a load through the above two pistols the other day for IDPA compliance. The ammo just happened to beh 115 gr JHP with a middling powder charge.

The G17 with its 4.? tube went 1125 average for th string. The G34 w/ its 5.? went 1175 average with the same ammo.

As somebody said above.........50fps, with that load anyhow.
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