Good Standard Deviation for 9mm 147g?

[ny32182]

I normally use Titegroup for everything, and I shoot 147's in 9mm. My SD's are normally around 30 FPS I think, so 10 sounds REALLY good to me too.

Two thoughts:

1) You are very right that this is getting into stuff that doesn't really matter from a competitive standpoint in action shooting like IDPA. Make a load that averages the power factor you want, and runs in your gun, and then don't mess with it. Time spent chasing some last little bit of ammo performance would be better spent practicing.

2) Going for a velocity of 880 is really scraping the floor, in my opinion. You'll probably be safe most of the time, but not all chronos are created exactly equal, and ambient conditions at the time will also have an affect on the velocity. I was grouped in the squad with all the pros at last weekend's Production nationals. One guy went 126.x, and another guy went 127.x There were some raised eyebrows, "I've got to call my ammo guy", and worried looks from some of the guys left in line. Mine chronoed 130.x, where as normally at home that load shows ~135 for me. Sometimes the chrono is just running lower than expected at the match. The recoil difference between 127pf and 135pf doesn't matter, but that difference can sure matter if you are on the low end, run into a slow chrono, and go sub-minor. It isn't worth it. Just go for 135pf and you'll always be safe.

 

[LiveLife]

Good point. That's why most match shooters load to 130 PF as "insurance" at the lower end of velocity and powder temperature sensitivity.

If you chrono'ed your match loads in summer, expect drop in velocity during colder months with "normal" temperature sensitive powders and higher with "reverse" temperature sensitive powders - http://www.thehighroad.org/showthread.php?p=10117881#post10117881

Here's an example shot with 17" JR carbine chronoed with just 20 degrees difference:

79 F RMR 115 gr HM RN 4.8 gr W231/HP-38 @ 1.130": 1303-1289-1298-1311-1323 fps

59 F RMR 115 gr HM RN 4.8 gr W231/HP-38 @ 1.130": 1275-1263-1253-1290-1248 fps

 

[Jim Watson]

W231 has been infamous for temperature sensitivity for a long time.
One reason is it less used in power factor ammo than it used to be.

 

[pdjms1]

Latest results. Note, use this info at your own risk. I am not advising that anyone should use these recipes. I am just reporting what I have done for reference.

Constants -
Ambient Air: 90 F
Location: Mansfield, Tx
Bullets: 147g Cimmeron LC (Moly)
Gun: STI Eagle 5"
Chrono: Caldwell Ballistics
Shots: 10 shots per group
distance: 11ft 6in from muzzle to chrono


Summary: I got some interesting results. VV needs to be bumped up in power and retested but seems promising (albeit expensive). CFE shot very well. Titegroup & HP-38 did well and I need to do some ladder charges to find out the proper charge for my needs as they ended up a littler higher then I would like. I think I am getting close to picking my top 3 for further testing. Hope this info is helpful for anyone else. Link to 5 shot targets from 21yrds picture at bottom of the post


3.5g HP-38:
Avg FPS - 940.5
Stdev - 11.7
min - 923
max - 958
MV - 941
note -

3.7g CFE:
Avg FPS - 880.5
Stdev - 15.7
min - 864
max - 913
MV - 881

3.7g VV N350:
Avg FPS - 849.5
Stdev - 15.3
min - 814
max - 867
MV - 850
note- this is underpowered but it felt very soft need to bump up to my PF goals

3.2g Titegroup:
Avg FPS - 954.8
Stdev - 7.5
min - 946
max - 967
MV - 955
note-

Freedom: (control)
Avg FPS - 922.3
Stdev - 9.0
min - 905
max - 934
MV - 922
note-

4.2g True Blue: (only 5 shots)
Avg FPS - 934.2
Stdev - 17.5
min - 908
max - 945
MV - 934
note-

Also had a friend test some of the same loads with his walther PPQ 4"

3.5g HP-38:
Avg FPS - 805.9
Stdev - 11.6

3.7g CFE:
Avg FPS - 894.9
Stdev - 6.7

3.7g VV N350:
Avg FPS - 805
Stdev - 22.3

3.2g Titegroup:
Avg FPS - 903.9
Stdev - 11.6