Monday, June 1, 2015

More .38 special & .357 Carbine observations: Now with 5" Gp100 and .38 SC loads

As the weather has turned very nice for us here in NW Ohio I've been able to spend more time on the range. In between helping run matches and doing range work I hauled out a chronograph to try a 2nd test batch of hand-loads I cooked up over the winter and late spring.

I shot these loads over two sessions, the first session was mostly handgun work with some carbine thrown in, the second session was mostly carbine with a few out of the revolver for comparison in velocity only.

Toying with multiple bullet weights I'm trying to get an idea what the carbine and revolver like as a combination. The twist rate in the carbine is 1:16 with 1:18 in the 5" GP100 revolver, although it was easy to find the max bullet weight these twist rates would stabilize I was not able to find what minimums were with velocity and weight, something I would have to toy with myself to see how well it shoots in the end anyways. All my cast bullets are straight wheel weights and lubed with the superb Carnuba Red from lars lube . In this test session I was also able to test bullets from my newly arrived 360640 mold a 125-135gr adjustble mold with removable hallow point pins. I cast about 150 bullets with the large HP pins in place and loaded those up.

First off I tried the odd duckling out of the bunch, I had loaded up a small batch of .38 Short colt rounds using the 125gr 360640 HP bullet the day before hitting the range and wanted to see how they shot (and sounded since the other short colt loads I've tried have been louder than expected) I loaded these with 2.0gr of red dot. The only bad thing was that the chronograph didn't want to read ANY of these rounds out of the revolver? probably operator error there.

All testing in both sessions was performed at a mere 50 yards, the 2nd session I scoped the Carbine with a low power scope for giggle. On to the data, we'll go from short colt to special and then magnum data.

  • .38 Short Colt (NOT SPECIAL)- 125gr cast 360640 HP - 2.0gr Red Dot  (shows potential with decent group) 

              77/357- 706,721,743

The above load shows massive efficiency potential if proven in further accuracy testing if you ask me

  • .38 Special- 75gr cast wadcutter-3.0gr of Bullseye
          GP100 5"-604,649,672

The above caught my attention as these loads were all assembled at the same time and the fact the velocity kept going up is something that I need to test again. The light 75gr pill might not give enough resistance for super consistent ignition in such a large bore? However 2 of the shots were touching at 50 yards with the 3rd only a few inches away. However the entire group was about 18" under the bull which isn't surprising really looking at the velocity and figuring drop at 50 yards.
  • .38 Special -125gr cast 360640 HP- 4.0gr red dot 
           77/357- 1126,1074,1117
           Gp-100 5"- 903,888,872

Nothing really jumped out with the above load,  I'll have to compare this load with my staple 158gr lee SWC over 4.2gr of red dot as I seem to remember I was getting almost 1000fps out of that load in a 4" barreled smith I would have expected at least upper 900's out of a 5" barrel with 4.0gr of red dot and a lighter bullet but then again this is part of learning.

  • .38 Special -173gr Keith - 5gr of Unique 
            77/357-1097,1088, did not capture 3rd shot
            GP100 5"-919, 871,910

This load shows a lot of potential in both guns, a heavy 173gr bullet moving at moderate speeds seems to always be the answer, although not that much gain in the carbine over the powder does that I've learned. Accuracy was definitely noted with this load.

  • .38 Special- 148gr SPEER factory wadcutter- 2.7gr of Bullseye

This "target" load is a staple of many bullseye shooters it seems like and with loads going up to just above 3.0gr of Bullseye there is some velocity to be gained but there really isn't a need when just punching paper. This load is a good place to start when looking for accuracy performance out of a gun. This load shot well in the carbine in previous tests and achieved 750+fps as I stated in the previous "observations" post.

  • .357 Magnum 125gr cast 360640 HP-15.0gr of 2400
          77/357 1749,1862,1780
          GP100 5"-1139,1352, did not capture 3rd shot - Erratic velocities between 1 and 2?

The above was a mild .357 load, was just a starting point to move up from I may revisit this load again and move down from it to see what happens to group size.

  • .357 Magnum 125gr cast 360640 HP- 16.5gr of 2400 Win primers
          Gp100- 1303,1403

  • .357 Magnum 125gr cast 360640 HP- 16.5gr of 2400 CCI primers


The above I shot in the rifle alternating primers between shots It seems like the CCI may be a little more consistent with 2400 in both the carbine and revolver. From here the primers looked good and I felt ok moving on to 17.0gr of 2400 which was still 2.5gr under "max" in one of my books.

  • .357 magnum 125gr cast 360640 HP- 17.0gr of 2400
           77/357-1978,1981,2008 (WOW)
           GP100-1403,1443 (no real flash compared to sim loads with jacketed bullets)

I was impressed when I saw the 2008 fps show up on the screen, though its of no real practical value its interesting to note that one can get into the upper 1900's with a pistol caliber carbine. Hitting the bullet energy calculator filling in 1990 for the velocity thats giving us just over 1100 ft-lbs of energy at the muzzle.

  • .357 Magnum 125gr Jacketed HP- 16.5gr of 2400
            77/357-1888,1888 with confirmed duplicate

The above seem VERY consistent in initial testing and its interesting to note here that the handgun velocity as well as rifle velocity was slightly lower with the jacketed bullet than with cast (lead is a natural lubricant...even if it sticks to barrels sometimes)

  • .357 Magnum 160gr Cast Wadcutter -12.0gr of 2400
           77/357-crap I forgot to write these down

This heavy wadcutter load showed potential in both carbine and revolver. I like the idea of a wadcutter as a hunting bullet

  • .357 Magnum 173gr Kieth SWC -12gr 2400
          GP100 5"- 1132,1142

  • .357 Magnum 173gr Kieth SWC- 12.5gr 2400
          GP100 5"-1142,1136,1077 

The 2nd load of .357 mag with the 173gr bullet and 2400 had no appreciable gain in velocity in the revolver although if fired in the carbine (didn't load enough ammo for that) it might have shown a little more velocity.

  • .357 Magnum 92Gr RN cast 14.0gr of 2400
           77/357-1727- ( I only fired one round over the chrono out of curiosity, solid round nose bullets don't excite me but I was curious what the little pill would do) 

  • .357 Magnum 148gr Speer wadcutter 5.5gr bullseye
           77/357-1321,1293 (Very accurate with following shots on target)
           GP100-1050,1083,1224 (erratic ?)

  • .357 Magnum 158gr Lee SWC 6.5gr unique
The above load with 6.5gr unique and the 158gr Lee SWC showed some promise to being a good load in both the revolver and the carbine. This 158gr bullet as I may have mentioned before is one of my favorite bullets for the .38/.357.

Some might be annoyed that I didn't go on about what was accurate and what wasn't but this is just a starting place for me to work from. I took further notes on accuracy but nothing was super stellar enough to be passed along, more so I thought the velocity readings were more interesting as from that we can calculate energy....something that we want to know if going afield.

1 comment:

Mo said...

Thanks for posting this excellent report. very informative and interesting.