Tested first batch - need guidance

[CZinSC]

I went to the range today and fired off about 75 of my very first batch of reloads, so I have a few questions. My batch was:

Winchester once fired brass

9mm 124 MG JHP

Win Primers

Titegroup 4.0gr

OAL 1.115

When I was shooting it was about 91 degrees. I was about 7-10 feet from the chrono. I got the following velocities: 1044,1027, 1031, 1056, 1038, 1033, 1021, 1043, 1044, 1021, 1033

I shot some WWB 115FMJ under the same conditions, for a comparsion, I got: 1179, 1174, 1187, 1200

Questions:

1 - How much will the heat affect the performance? Would I have gotten higher fps if it was cooler, or lower?

2 - Is it normal to have that much variance in readings? I would have thought from the same batch the readings would have been more similar?

3 - Based on my calculatons, I got PF's 126.6 up to 130.944. Average was 128.4. If going to a major match, I'd rather have some breathing room, so I'd like to go a litter hotter. Should I go up .1 or .2 grains?

[mhop]

i have had no change in titegroup from 35 degrees to 100, in my sp-01 with 4.0 grains i get 130 pf i would go up .1 grain and call it good

[G-ManBart]

I went to the range today and fired off about 75 of my very first batch of reloads, so I have a few questions. My batch was:

Winchester once fired brass

9mm 124 MG JHP

Win Primers

Titegroup 4.0gr

OAL 1.115

When I was shooting it was about 91 degrees. I was about 7-10 feet from the chrono. I got the following velocities: 1044,1027, 1031, 1056, 1038, 1033, 1021, 1043, 1044, 1021, 1033

I shot some WWB 115FMJ under the same conditions, for a comparsion, I got: 1179, 1174, 1187, 1200

Questions:

1 - How much will the heat affect the performance? Would I have gotten higher fps if it was cooler, or lower?

2 - Is it normal to have that much variance in readings? I would have thought from the same batch the readings would have been more similar?

3 - Based on my calculatons, I got PF's 126.6 up to 130.944. Average was 128.4. If going to a major match, I'd rather have some breathing room, so I'd like to go a litter hotter. Should I go up .1 or .2 grains?

First off, your extreme spread (ES, high to low) is actually pretty good at 35fps. Did you write down what your standard deviation (SD) was? I'd guess something like 10 or less which is also quite good. I'd be happy with those numbers, but you need to bump that load quite a bit. If you go sub minor, you're shooting for fun, not score. If you go up a tenth, you're almost within the range of variation that's normal from shot to shot, so you may not see much change, and you need to be well above 130PF to be sure. Right now there's a thread in the "match screwups" section about someone going under 125PF after their load, which went something like 129 at home, went 122 at Area-5. Try to get 135PF, it won't slow you down, and you will be sure of making PF at any match you go to. I'd go up .2gr and chrono, but I'd suggest running strings of 20 shots, not just ten. Chrono on multiple days, in different conditions, until you know what to really expect from your load. R,

[Sarge]

Others have had fluctuations though. TG is temp sensitive, meaning the hotter the temp the hotter the load. as it gets cool the pressures will decrease along with velocity and PF. How much? Thats a guess but there is plenty of data here to do some research on the subject. Don't ever count on any given load to perform as you expect it to in different weather unless you have chronoed under the same conditions.

What gun are you shooting these out of? You can safely go to 4.2 easy. I personally would shoot for 135PF. There are plenty of horror stories going around about not making pf at major matches. MG generally take a tenth or so more powder to bring them up to speed compared to some other bullets. I was running 4.3-4.4 TG with MG 124's @1.14 out of my M&P pro last year.

Once you get up around 135 pf then start paying attention to your SD and ES readings off your chrono. After you get to pf those are the most important numbers. Good ES numbers are in the teens while good SD numbers are in the single digits. This past weekend I chronoed my loads with N320 and got an av ES of 13 and av SD of 5.5.

Edited to add: you want to stay at ten feet from the chrono as this will eliminate muzzle blast as a factor.

Edited June 21, 2010 by Sarge

[CZinSC]

Did you write down what your standard deviation (SD) was?

No, how do I figure that out? I found an SD calculator on line, and it said 9.82

but I'd suggest running strings of 20 shots, not just ten.

I shot strings of about 20, but unfortunately, after the first several readings, I did a quick calculation on my Blackberry's calculator, and must have made a mistake, because I was thinking i was under 125 for most readings. Duh! So I stopped writing down the readings.

What gun are you shooting these out of?

CZ SP01

[Sarge]

What chrono are you using? I use a pro chrono digital and it gives me the following at a touch of the review button : Hi, Lo, AV, ES, SD for the entire string. I thought all chronos did these basic measurements.

I'm not too high tech so I right down everything when I chrono. The only thing I really have to calculate is PF by multiplying the AV times weight.

Also, even though I have never owned one, it is my understanding CZ's like shorter loads. Have you removed the barrel and done a chamber check with your loads to make sure they plop in and fall right out without touching the rifling?

[G-ManBart]

Others have had fluctuations though. TG is temp sensitive, meaning the hotter the temp the hotter the load. as it gets cool the pressures will decrease along with velocity and PF. How much? Thats a guess but there is plenty of data here to do some research on the subject. Don't ever count on any given load to perform as you expect it to in different weather unless you have chronoed under the same conditions.

What gun are you shooting these out of? You can safely go to 4.2 easy. I personally would shoot for 135PF. There are plenty of horror stories going around about not making pf at major matches. MG generally take a tenth or so more powder to bring them up to speed compared to some other bullets. I was running 4.3-4.4 TG with MG 124's @1.14 out of my M&P pro last year.

Once you get up around 135 pf then start paying attention to your SD and ES readings off your chrono. After you get to pf those are the most important numbers. Good ES numbers are in the teens while good SD numbers are in the single digits. This past weekend I chronoed my loads with N320 and got an av ES of 13 and av SD of 5.5.

Edited to add: you want to stay at ten feet from the chrono as this will eliminate muzzle blast as a factor.

Actually, I'd call ES in the teens and SD in the low single digits as great, not good. The lowest SD I've ever gotten was something like 4.5 (with N320 in 9mm). Even an ES of 25-30 and an SD of 10 or so would be good. I've shot groups in the 1-1.25" at 25yds with a load that higher ES and SD than that

[gm iprod]

I use heaps of TG in 38Super and some in 9mm. I use a 125gr Zero and your results are so close to mine in 9mm that you stole my notebook.

4.2gr is a lot hotter than I like, I found 4.1gr gave my about 1080 average with the lowest going about 1065. That would give yoy a PF of 133 or so at worst. I would be happy with that. Even at the coldest here (which is not cold by US standards) I never drop below 130pf with that. I do load an OAL of 1.15max.

FYI, ammo loaded here in New Zeland in May (winter about 40F) and shot in Missouri one week later (85F) gave my the exact same velocity. Even when I went to AZ and shot in 110F they still only imporved 20fps. So who knows. Extreme increase in temperature (ie: stored in hot direct sunlight) will be an issue. Properly stored but warm ammo will not be something that I would panic over.

Do not go below 130pf under any circumstances though.

[CZinSC]

I use heaps of TG in 38Super and some in 9mm. I use a 125gr Zero and your results are so close to mine in 9mm that you stole my notebook.

I only peeked at it...I actually chose to steal your wallet instead!

Seriously though, thank you all for the data. Looks like I'm on the right path. Just need to tweak a thing or two and hopefully test another batch before this week's match.

[CZinSC]

What chrono are you using? I use a pro chrono digital and it gives me the following at a touch of the review button : Hi, Lo, AV, ES, SD for the entire string. I thought all chronos did these basic measurements.

I'm not too high tech so I right down everything when I chrono. The only thing I really have to calculate is PF by multiplying the AV times weight.

Also, even though I have never owned one, it is my understanding CZ's like shorter loads. Have you removed the barrel and done a chamber check with your loads to make sure they plop in and fall right out without touching the rifling?

I guess it would have helped reading the directions. I have the ProChrono Digital. So I'll have to check out that review button.

Yes, I was using the barrel for a case gauge. I have the Dillon case gauge and found that with the MG124 JHP with an OAL of 1.117 the round will easily fall free of the gauge, but will not fall free from the barrel. At 1.116 it will. When I finally set the die, i was at 1.115, so i'm good to go there.

[Sarge]

I guess it would have helped reading the directions. I have the ProChrono Digital. So I'll have to check out that review button.