Revisiting Old Load/Chrono Data

[Old Jeff H]

At some point I intend to load up a bunch more 180gr JHP 40 S&W so I was reviewing my old data (from almost 11 years ago). This is my chrono data for 180gr XTP's, Hodgdon Longshot, WSP primer, and shot through my Ruger Police Carbine. Right hand column is charge weight.

1) 1124.0 -123.4 6.5
2) 1153.0 -94.4 6.6
3) 1161.0 -86.4 6.7
4) 1184.0 -63.4 6.8
5) 1210.0 -37.4 6.9
6) 1227.0 -20.4 7
7) 1265.0 17.6 7.1
8) 1258.0 10.6 7.2
9) 1248.0 0.6 7.3
10) 1291.0 43.6 7.4
11) 1292.0 44.6 7.5
12) 1294.0 46.6 7.6
13) 1313.0 65.6 7.7
14) 1312.0 64.6 7.8
15) 1284.0 36.6 7.9
16) 1342.0 94.6 8

Tell me what you think was going on here, what your final charge would be, and what you might try differently. I have my own ideas, but curious as to what you think as well.

 

[Old Jeff H]

No one?

My guess is that beyond 7.4 grains I was getting incomplete powder burn? The only anomaly with that theory was the bump at 8.0 grains - maybe it just happened to get a more complete burn that shot.

I ended up settling on 7.4 grains as my final load, but I'm thinking about trying the load over again but with magnum primers.

 

[knockonit]

No one?

My guess is that beyond 7.4 grains I was getting incomplete powder burn? The only anomaly with that theory was the bump at 8.0 grains - maybe it just happened to get a more complete burn that shot.

I ended up settling on 7.4 grains as my final load, but I'm thinking about trying the load over again but with magnum primers.

hehe, you be a lone 40 cal shooter, hehehe, its a thing ya know, do what ya gotta do, wind some up, send'm down range, and finger it out.
times they be a changing, have ammo for every gat, as much as you can, the days of freedom could be numbered
RJ

 

[delta6]

Did you only fire one round of each powder weight?

 

[Ben7]

That’s mighty odd.

 

[Old Jeff H]

Did you only fire one round of each powder weight?

Yes. I wasn't going for groups, I was looking at velocity. The following weekend I fired 50 rounds at 7.4 grains with an average of 1246.6 fps and an SD of 24.9. So I don't think I missed out on anything by not loading up multiple rounds of each charge for the velocity ladder test?

 

[Old Jeff H]

That’s mighty odd.

I agree. Especially with what happened with 7.1 to 7.3 and 7.4 to 7.9.

 

[delta6]

As a general rule.. one round doesn't really give you verifiable emperical data.

 

[Old Jeff H]

No one?

My guess is that beyond 7.4 grains I was getting incomplete powder burn? The only anomaly with that theory was the bump at 8.0 grains - maybe it just happened to get a more complete burn that shot.

I ended up settling on 7.4 grains as my final load, but I'm thinking about trying the load over again but with magnum primers.

hehe, you be a lone 40 cal shooter, hehehe, its a thing ya know, do what ya gotta do, wind some up, send'm down range, and finger it out.
times they be a changing, have ammo for every gat, as much as you can, the days of freedom could be numbered
RJ

If I ever get my hands on a Ruger PC Carbine in 40 I'll be loading the hell out of 'em. :lol:

 

[Old Jeff H]

As a general rule.. one round doesn't really give you verifiable emperical data.

True, but I think the 50 shot group velocity and SD validate the powder weights and velocities were accurate.

There are clearly a couple of odd nodes there. Just wondering if they're related to powder burn, or the behavior of that particular combination of components and the carbine.

 

[delta6]

Yes, only for those 50 shots, but doesn't invalidate any of the other combinations which could show better results.

 

[Old Jeff H]

Yes, only for those 50 shots, but doesn't invalidate any of the other combinations which could show better results.

Hmm. I based this test on the theory of the 10 shot load development ladder I used for my F-T/R loads. Only I wasn't looking for nodes in accuracy (particularly since this rifle's accuracy is poor even at 50 yards) but for changes in velocity. It seems reasonable that if you're confident that your powder charges are accurate, you should be able to see an accurate representation of velocity changes as you progress through the shots. If I was able to pick a charge weight and validate it with a 50 shot group that well represented what I saw from the previous test, I'm inclined to believe the previous test was reliable?

 

[delta6]

Yes, only for those 50 shots, but doesn't invalidate any of the other combinations which could show better results.

Hmm. I based this test on the theory of the 10 shot load development ladder I used for my F-T/R loads. Only I wasn't looking for nodes in accuracy (particularly since this rifle's accuracy is poor even at 50 yards) but for changes in velocity. It seems reasonable that if you're confident that your powder charges are accurate, you should be able to see an accurate representation of velocity changes as you progress through the shots. If I was able to pick a charge weight and validate it with a 50 shot group that well represented what I saw from the previous test, I'm inclined to believe the previous test was reliable?

Yes... if the 16 shot ladder, firing 1 shot for each charge, was reliable. I guess one could argue both sides. I have found especially with pistols, that one shot per charge is not always very reliable.

 

[shawnff]

I would also think it is the chrono. I have a couple of them, and the old school ones that use light can have wild results from time to time.

 

[Old Jeff H]

I would consider that a possibility, but I fired 11 strings that day and all the other ones seem fine?

 

[knockonit]

no doubt chronos are subject to some issues, i have a new one that doesn't like direct sunlight, in shade its the cats meow, otherwise, you m ay think you drank the celebratory libation way too soon.
Rj

 

[delta6]

I would also think it is the chrono. I have a couple of them, and the old school ones that use light can have wild results from time to time.

Agree..

 

[Old Jeff H]

If it was the chrono, it's a bit odd that it chose only that string to behave that way.


CED Data Collector - 5/23/10
(f = flyers, (ED) = edited shots)

Total Strings = 11
Feet Per Second

String 1 - Federal 55gr FMJ Factory Ammo
3069
3057
3060
3046
3082

High: 3082.0
Low: 3046.0
E.S.: 36.0
Ave.: 3062.8
S.D.: 13.5
95%: ｱ18.7

String 2 Hornady 55gr FMJ LC Brass 23 Grains H335
2700
2663
2627
2668

High: 2700.0
Low: 2627.0
E.S.: 73.0
Ave.: 2664.5
S.D.: 29.9
95%: ｱ54.9

String 3 Hornady 55gr FMJ LC Brass 23.5 Grains H335
2670
2682
2671
2740

High: 2740.0
Low: 2670.0
E.S.: 70.0
Ave.: 2690.8
S.D.: 33.3
95%: ｱ61.2

String 4 Hornady 55gr FMJ LC Brass 24.0 Grains H335
2782
2809
2786
2785

High: 2809.0
Low: 2782.0
E.S.: 27.0
Ave.: 2790.5
S.D.: 12.4
95%: ｱ22.8

String 5 Hornady 55gr FMJ LC Brass 24.5 Grains H335
2841
2839
2842
2892

String 5A Hornady 55gr FMJ LC Brass 25.0 Grains H335
2868
2901
2889
2885

High: 2939.0
Low: 2841.0
E.S.: 98.0
Ave.: 2882.1
S.D.: 32.2
95%: ｱ28.8

String 6 Federal Factory 180 FN FMJ
1) 1103.0 0.7
2) 1100.0 -2.3
3) 1095.0 -7.3
4) 1097.0 -5.3
5) 1112.0 9.7
6) 1094.0 -8.3
7) 1111.0 8.7
8) 1110.0 7.7
9) 1103.0 0.7
10) 1098.0 -4.3

High: 1112.0
Low: 1094.0
E.S.: 18.0
Ave.: 1102.3
S.D.: 6.7
95%: ｱ5.1

String 7 - Speer Brass 180 Gr XTP Longshot Powder
1) 1124.0 -123.4 6.5
2) 1153.0 -94.4 6.6
3) 1161.0 -86.4 6.7
4) 1184.0 -63.4 6.8
5) 1210.0 -37.4 6.9
6) 1227.0 -20.4 7
7) 1265.0 17.6 7.1
8) 1258.0 10.6 7.2
9) 1248.0 0.6 7.3
10) 1291.0 43.6 7.4
11) 1292.0 44.6 7.5
12) 1294.0 46.6 7.6
13) 1313.0 65.6 7.7
14) 1312.0 64.6 7.8
15) 1284.0 36.6 7.9
16) 1342.0 94.6 8

High: 1342.0
Low: 1124.0
E.S.: 218.0
Ave.: 1247.4
S.D.: 64.6
95%: ｱ35.6

String 8 155 Gr XTP 5.4gr Titegroup
1) 1181.0 -35.0
2) 1214.0 -2.0
3) 1217.0 1.0
4) 1218.0 2.0
5) 1250.0 34.0

High: 1250.0
Low: 1181.0
E.S.: 69.0
Ave.: 1216.0
S.D.: 24.4
95%: ｱ33.9

String 9 155 Gr XTP 5.6gr Titegroup
1) 1249.0 -11.6
2) 1262.0 1.4
3) 1251.0 -9.6
4) 1273.0 12.4
5) 1268.0 7.4

High: 1273.0
Low: 1249.0
E.S.: 24.0
Ave.: 1260.6
S.D.: 10.5
95%: ｱ14.6

String 10 155 Gr XTP 5.8gr Titegroup
1) 1243.0 -23.0
2) 1265.0 -1.0
3) 1278.0 12.0
4) 1277.0 11.0
5) 1267.0 1.0

High: 1278.0
Low: 1243.0
E.S.: 35.0
Ave.: 1266.0
S.D.: 14.1
95%: ｱ19.6

String 11 Winchester Factory 180gr JHP
1) 1078.0 -16.8
2) 1089.0 -5.8
3) 1113.0 18.2
4) 1103.0 8.2
5) 1091.0 -3.8

High: 1113.0
Low: 1078.0
E.S.: 35.0
Ave.: 1094.8
S.D.: 13.5
95%: ｱ18.7

(End Of Data)

Just for S's & G's, I'm going to reproduce the load but with 3 rounds at each charge weight.