Barrel legnth vs Velocity ? for 357

crimsondave · February 16, 2010, 02:59 PM

OK. Can anyone say what the difference would be in velocity of a 18.5" barrel vs 24" barrel in .357 mag, 124 gr XTP w 22.0 gr of H110? I'm at 1500 out of a 4" S&W.

SL1 · February 16, 2010, 03:32 PM

Dave,

That is a little hard to answer, because QuickLOAD's defaults give me a serious overload with 22.0 grains of H-110 in that bullet + cartridge combination. Looking at some load data, it appears that 22.0 grains is probably based on the old CUP standard, so I am not exactly sure what pressure to try to match in psi.

So, here is what I did to get you an estimate. I increased the case capacity until I got the pressure down to 44,600 psi and noticed that the velocity in a [4" barrel + 1.7" cylinder =] 5.7" barrel was about 1750 psi. QuickLOAD can't calculate the effect of the barrel-to-cylinder gap, so that leaves about 250 fps to account for that to get to what you are actually observing in your revolver. Revolvers vary a lot in velocity from gun-to-gun, so that isn't necessarily the right match.

IF that is a reasonable representation of your load, then the velocities for the 18.5" and 24" barrels are 2286 and 2379 fps.

I also tried increasing the case capacity to get the pressure down to 40,000 psi, and got 1699, 2246, and 2341 fps for the 5.7", 18.5" and 24" (unvented) barrel lengths, respectively. That seems as reasonable as the first try.

So, my best guess is that you will get something like a 95 fps difference between the two longer barrel lengths with that load. But, remember, this in only a computer program, and reality may vary.

SL1

kiwi56 · February 17, 2010, 12:58 AM

Dave my figures from Load From A Disk based on 23.4 grains of H110 is as follows.
inch barrel velocity pressure (cup)
16 2152 44,466
18 2187 44,400
20 2215 44,342
22 2239 44,306
24 2261 44,307

Lost Sheep · February 17, 2010, 02:52 AM

The short answer is, "yes".

www.ballisticsbytheinch.com/

Lost Sheep

crimsondave · February 17, 2010, 06:13 AM

Thanks for all the replies. Very helpful.

Don P · February 17, 2010, 11:35 AM

Quote:

OK. Can anyone say what the difference would be in velocity of a 18.5" barrel vs 24" barrel in .357 mag,

Quote:

I'm at 1500 out of a 4" S&W.

I'm so confused?

crimsondave · February 17, 2010, 11:52 AM

Quote:

I'm so confused?

Want a rifle in that caliber.

Don P · February 17, 2010, 01:05 PM

Quote:

Want a rifle in that caliber.

No thanks. 38spl maybe since I know nothing about rifles

crimsondave · February 17, 2010, 02:17 PM

"I" want a rifle in that caliber. Weighing pros and cons of barrel legnth.

February 16, 2010, 02:59 PM	#1
crimsondave Senior Member Join Date: September 30, 2009 Location: North Augusta, SC Posts: 490	Barrel legnth vs Velocity ? for 357 OK. Can anyone say what the difference would be in velocity of a 18.5" barrel vs 24" barrel in .357 mag, 124 gr XTP w 22.0 gr of H110? I'm at 1500 out of a 4" S&W.

February 17, 2010, 12:58 AM	#3
kiwi56 Senior Member Join Date: May 19, 2009 Location: Auckland NewZealand Posts: 350	Barrel Length vs velocity Dave my figures from Load From A Disk based on 23.4 grains of H110 is as follows. inch barrel velocity pressure (cup) 16 2152 44,466 18 2187 44,400 20 2215 44,342 22 2239 44,306 24 2261 44,307

February 17, 2010, 02:52 AM	#4
Lost Sheep Senior Member Join Date: January 24, 2009 Location: Anchorage Alaska Posts: 3,341	Ballistics by the inch The short answer is, "yes". www.ballisticsbytheinch.com/ Lost Sheep

February 16, 2010, 03:32 PM	#2
SL1 Senior Member Join Date: November 8, 2007 Posts: 2,001	Dave, That is a little hard to answer, because QuickLOAD's defaults give me a serious overload with 22.0 grains of H-110 in that bullet + cartridge combination. Looking at some load data, it appears that 22.0 grains is probably based on the old CUP standard, so I am not exactly sure what pressure to try to match in psi. So, here is what I did to get you an estimate. I increased the case capacity until I got the pressure down to 44,600 psi and noticed that the velocity in a [4" barrel + 1.7" cylinder =] 5.7" barrel was about 1750 psi. QuickLOAD can't calculate the effect of the barrel-to-cylinder gap, so that leaves about 250 fps to account for that to get to what you are actually observing in your revolver. Revolvers vary a lot in velocity from gun-to-gun, so that isn't necessarily the right match. IF that is a reasonable representation of your load, then the velocities for the 18.5" and 24" barrels are 2286 and 2379 fps. I also tried increasing the case capacity to get the pressure down to 40,000 psi, and got 1699, 2246, and 2341 fps for the 5.7", 18.5" and 24" (unvented) barrel lengths, respectively. That seems as reasonable as the first try. So, my best guess is that you will get something like a 95 fps difference between the two longer barrel lengths with that load. But, remember, this in only a computer program, and reality may vary. SL1

February 17, 2010, 06:13 AM	#5
crimsondave Senior Member Join Date: September 30, 2009 Location: North Augusta, SC Posts: 490	Thanks for all the replies. Very helpful.

February 17, 2010, 02:17 PM	#9
crimsondave Senior Member Join Date: September 30, 2009 Location: North Augusta, SC Posts: 490	"I" want a rifle in that caliber. Weighing pros and cons of barrel legnth.