Chrony and 135 gr. Gold Dot .38's

[BE Mike]

A buddy invited me to test some loads on his Chrony. When testing the Speer short barrel 135 gr. Gold Dot .38 SPL loads in my S&W 642 we got velocities in the 880-890 range. When I shot the same round in my S&W 60-10 the velocity went up another 90 fps. This surprised me, as I usually apply the rule of thumb of an increase of 35-50 fps for every extra inch of barrel. The Gold Dot round in .357 mag produced velocities near 1,400 fps out of the model 60-10! The temperature was around 85 degrees and we were about 10' from the Chrony. I had never used a chronograph and have to say that this session was very informative.

[Erich]

Yep, time with an actual chronograph will have you rolling your eyes whenever you see a "rule of thumb" posted on a thread about barrel length and velocity.

[acl864]

Originally Posted by Erich

Yep, time with an actual chronograph will have you rolling your eyes whenever you see a "rule of thumb" posted on a thread about barrel length and velocity.

I agree. There are other factors at work in addition to barrel length. B/C gap, powder burn rate, bullet fit and bore condition are some that come to mind. If you want to know the velocity of a particular load. You can make an educated guess, which may or may not be right, or you can run it across a chrono.

[Rule3]

And here I always thought the thumb rule was 100 FPS per inch??

[Alk8944]

The only time that velocity difference per inch means anything is if the test is run in the same gun and the barrel shortened! When shooting different guns with the same ammunition it is not unusual to see as much as 150-200 FPS difference brtween different guns having the same barrel length. This is particulerly true with revolvers.

[BE Mike]

I was really floored that the .357 mag. Gold Dot with 135 gr. bullet would produce such high velocities out of a 3" barrel. It would be interesting to see how well it expands and holds together in gelatin at those velocities. I'll leave that to someone else.

[OKFC05]

It would be interesting to see how well it expands and holds together

YouTube - ‪Snub Nose Water Expansion Test - .357 Mag - 135 Gr. Short Barrel Gold Dot‬‏

[BE Mike]

Those tests in water look pretty impressive. I've loaded up some of the GD 135 gr. bullets in .38 SPL. I used the recommended 6.4 grains of Alliant Power Pistol. They don't quite match the velocity of factory ammo (about 60 fps short), and there are no signs of high pressure. I think I might step up the charge a tenth of a grain or two. Has anyone loaded these bullets with more than 6.4 grains of Power Pistol?

[roundgunner]

My results with factory ammo were not that fast. I have duplicated it for my practice.
357 135 GDSB
2" 952
4" 1132

[maiko]

Originally Posted by BE Mike

A buddy invited me to test some loads on his Chrony. When testing the Speer short barrel 135 gr. Gold Dot .38 SPL loads in my S&W 642 we got velocities in the 880-890 range. When I shot the same round in my S&W 60-10 the velocity went up another 90 fps. This surprised me, as I usually apply the rule of thumb of an increase of 35-50 fps for every extra inch of barrel. The Gold Dot round in .357 mag produced velocities near 1,400 fps out of the model 60-10! The temperature was around 85 degrees and we were about 10' from the Chrony. I had never used a chronograph and have to say that this session was very informative.

near 1400 seems right for the 125gr 357 load but not the 135gr

[BE Mike]

Originally Posted by maiko

near 1400 seems right for the 125gr 357 load but not the 135gr

Actually the velocity recorded was 1,387 fps for the factory load. The handloads for the .357 Mag. with 135 gr. bullet with 9.6 grains of Power Pistol were consistently around 1,200 fps. This was out of a 3" barrel S&W model 60-10. We were around 1,500 feet above sea level and around 85 degrees with 55% humidity that day.

[nitesite]

Originally Posted by BE Mike

Actually the velocity recorded was 1,387 fps for the factory load. The handloads for the .357 Mag. with 135 gr. bullet with 9.6 grains of Power Pistol were consistently around 1,200 fps. This was out of a 3" barrel S&W model 60-10. We were around 1,500 feet above sea level and around 85 degrees with 55% humidity that day.

I would never have imagined that a 135-gr factory load would approach 1400-fps from a 3" J-frame.

Wow! It sounds punishing!!!

[Erich]

My handloaded-to-Speer-recommendation loads were not that warm (and the .38s were not all that accurate):

.38 Spl +P with 6.4 gr Power Pistol (5950' > sea level, 10% humidity, winds calm, 58° F):

From the 3" 36-1: M 917.8/ES 75.9/SD 24.59
From the 2 1/8" DS: M 863.6/ES 59.7/SD 19.65
From the 1 7/8" 37-2: M 854.3/ES 78.9/SD 40.66

.38 Spl +P with 7.2 gr. HS-6 and a CCI magnum primer in .38 PMC cases, with a firm crimp (5950'>sea level, 57°F, c. 40% humidity):

4" GP-100: M 978.8 fps/ES 96.48/SD 36.37
3" S&W 36-1: M 858.8/ES 83.22/SD 33.74
2 1/8" DS: M 827.8/ES 92.01/SD 38.47

I wasn't thrilled with these results, so I shot it again:

4" GP-100: M 942.0/ES 103.1/SD 41.91
3" S&W 36-1: M 878.6/ES 67.11/SD 26.96
2 1/8" DS: M 813.2/ES 46.25/SD 17.74

Okay, now for some .357 Magnum loads from the 2" Rhino (c.55 degrees F/30% humidity/Range (5950'>sea level)

.357 Magnum loadings:

AA#7 12.1 gr under 135-gr Speer short barrel GDHP, CCI 500 std primer, firm roll crimp:

First six: M 1012/ES 39.88/SD 17.66
Second six: M 1022/ES 69.85/SD 25.96

Power Pistol 9.6 gr under same bullet, w/ same primer/crimp:

First six: M 1013/ES 37.42/SD 16.24
Second six: M 1025/ES 46.83/SD 16.03

AA loading was much louder. I'm carrying the Magnum Power Pistol loading in the Rhino . . . seems like a decently useful loading.

[snuf]

Erich:
Thanks for the info. I've been using Power Pistol with 125gr .357 loads, with good results and I'm getting ready to try loading some 125gr .38 Spls with it.

[Erich]

You're welcome - sorry that I don't have data from other barrel lengths - I was specifically looking for a carry load for the Rhino.

[snuf]

I'm interested in the 2"-4" barrel lengths, perfect.