Jump to content
Brian Enos's Forums... Maku mozo!

Powder temp sensitivity


jstagn

Recommended Posts

Would like chrono results on temperature sensitivity on the following powders:

E-3, Claydot, Clays Vitn320 all in 40 cal. Seems like e-3 and Claydot did not show any for me, interested in hearing from other reloaders.. Thanks..........

PS I have read conflicting reports on Clays and Vitn320..

Link to comment
Share on other sites

My limited testing has shown that e3 is slightly temp sensitive which is contrary to what many others say.

I'm using e3 for 40 minor.

ETA:

3.2gr e3, 155gr Ranier, 1.125" 129PF @ 80F

Exact same load at 38F, 124PF. FTE's every now and again.

Link to comment
Share on other sites

My testing of e3 doesn't show a bit of difference from 29 to 105 degrees. I also placed the ammo I was testing in the direct sunlight for a few minutes (the summer test) trying to heat it up for even more spread. I was testing the same exact batch of ammo, fired from the same gun, and over the same chrono. My computer couldn't find a difference.

Link to comment
Share on other sites

Well, I haven't found e3 to be temp sensitive at all. Here is some comparison data:

CCI 500 primer, 3.1gr e3, 180gr LTC loaded to 1.135". 10-shot strings- same batch of reloads.

39 deg: Avg vel, 844 fps, SD 8.98, 151.9 PF

85 deg: Avg vel, 844 fps, SD 8.88, 151.9 PF

I'd say that was pretty consistent, and not indicative of much temperature sensitivity (at least within that temp range).

I only shoot Clay Dot in 45 ACP, and it does show a little temp sensitivity. However, I've been shooting it in the 16 to 35 degree temp range, so I don't have a definite opinion yet.

I don't know about N320. I do know that N310 is extremely temp sensitive in 45 ACP. Geez, my bullseye load goes 674fps @ 41 deg, 733 fps @ 56 deg and 749 @ 85 deg. If you shoot this load below freezing, it barely operates the gun.

Link to comment
Share on other sites

For 320, when the outside temps get down in the 40's and lower, you'll lose 10-30 fps. Not a big deal if you have a comfortable margin built in to your PF, but if you're blade running, you will get hosed at a chrono eventually.

for general every day use, not much of difference to make a big deal.

eta: this is based on first hand experience two winters in a row

Link to comment
Share on other sites

My testing of e3 doesn't show a bit of difference from 29 to 105 degrees. I also placed the ammo I was testing in the direct sunlight for a few minutes (the summer test) trying to heat it up for even more spread. I was testing the same exact batch of ammo, fired from the same gun, and over the same chrono. My computer couldn't find a difference.

You need to heat it up for more than a few minutes for the powder to actually heat up.

Link to comment
Share on other sites

Well, I haven't found e3 to be temp sensitive at all. Here is some comparison data:

CCI 500 primer, 3.1gr e3, 180gr LTC loaded to 1.135". 10-shot strings- same batch of reloads.

39 deg: Avg vel, 844 fps, SD 8.98, 151.9 PF

85 deg: Avg vel, 844 fps, SD 8.88, 151.9 PF

I'd say that was pretty consistent, and not indicative of much temperature sensitivity (at least within that temp range).

I only shoot Clay Dot in 45 ACP, and it does show a little temp sensitivity. However, I've been shooting it in the 16 to 35 degree temp range, so I don't have a definite opinion yet.

I don't know about N320. I do know that N310 is extremely temp sensitive in 45 ACP. Geez, my bullseye load goes 674fps @ 41 deg, 733 fps @ 56 deg and 749 @ 85 deg. If you shoot this load below freezing, it barely operates the gun.

Was your ammo 39F as well? Where do you store your ammo? Chances are if you store your ammo inside and drive to the range, your powder isn't anywhere near ambient temp when very cold or very hot.

Link to comment
Share on other sites

My testing of e3 doesn't show a bit of difference from 29 to 105 degrees. I also placed the ammo I was testing in the direct sunlight for a few minutes (the summer test) trying to heat it up for even more spread. I was testing the same exact batch of ammo, fired from the same gun, and over the same chrono. My computer couldn't find a difference.

You need to heat it up for more than a few minutes for the powder to actually heat up.

Well it was in the bed of my pickup for a 30 minute drive to the range in ambient temps of 103 to 108 during the drive. My truck thermometer said 105 when I pulled up to the gate. Then in direct sun while I setup the chrono and shooting other loads. Trust me the Oklahoma sun on a 105 degree day is plenty brutal enough.

Link to comment
Share on other sites

My testing of e3 doesn't show a bit of difference from 29 to 105 degrees. I also placed the ammo I was testing in the direct sunlight for a few minutes (the summer test) trying to heat it up for even more spread. I was testing the same exact batch of ammo, fired from the same gun, and over the same chrono. My computer couldn't find a difference.

You need to heat it up for more than a few minutes for the powder to actually heat up.

Well it was in the bed of my pickup for a 30 minute drive to the range in ambient temps of 103 to 108 during the drive. My truck thermometer said 105 when I pulled up to the gate. Then in direct sun while I setup the chrono and shooting other loads. Trust me the Oklahoma sun on a 105 degree day is plenty brutal enough.

Yeah, it was probably close to ambient temp then.

Link to comment
Share on other sites

d_striker, I have no way of knowing what the actual temp of the ammo was. I can say that on the 39 deg day it sat on the bench for about two hours before it was shot over the chrono. It was the last string shot.

On the 85 degree day, it was the second string shot, so it sat on the bench for between 30 and 45 minutes before being shot.

In both cases the ammo was close enough to ambient that I wouldn't worry about it. Even if the temp of the ammo was 80 and 45 respectively, the point remains the same. There was no temp sensitivity noted.

Link to comment
Share on other sites

d_striker, I have no way of knowing what the actual temp of the ammo was. I can say that on the 39 deg day it sat on the bench for about two hours before it was shot over the chrono. It was the last string shot.

On the 85 degree day, it was the second string shot, so it sat on the bench for between 30 and 45 minutes before being shot.

In both cases the ammo was close enough to ambient that I wouldn't worry about it. Even if the temp of the ammo was 80 and 45 respectively, the point remains the same. There was no temp sensitivity noted.

I believe you.

I've been scratching my head on my findings as the large majority of e3 users report no temperature sensitivity.

Link to comment
Share on other sites

"I've been scratching my head on my findings as the large majority of e3 users report no temperature sensitivity."

I think it is not temp sensitivity you are seeing, but load variation. It may be that your load is too light with that 155gr bullet. I tried to get 155s to run at minor, but gave up when I could not get the consistency I wanted. SDs were just plain lousy. Things started to shape up at 132PF and continued to improve as I upped the speed. At 144PF the SDs were still at 14, so I just gave up.

My go to 180gr minor load gives 139FP with SDs in the 6-7 range. It is super accurate to boot. The best I've been able to do with 165s was SDs in the 10-11 range.

If you are getting high SDs with that load, it may just have been luck that gave you a higher velocity at 80. Did you use the same batch of reloads for each test? How many shots in each string?

Link to comment
Share on other sites

If you have a load that is inconsistent, then no amount of testing in different temps is going to prove anything. I also am sure that certain combinations will also differ. You have to have the same load done at the same time and shot at least 10-20 rounds to have a decent average. Then you can save some of that load and test on a hot/cold day. I also warm up my gun by shooting from 20-30 rounds just to have a 'warmed-up' barrel. Then the chrono begins.

Link to comment
Share on other sites

"I've been scratching my head on my findings as the large majority of e3 users report no temperature sensitivity."

I think it is not temp sensitivity you are seeing, but load variation. It may be that your load is too light with that 155gr bullet. I tried to get 155s to run at minor, but gave up when I could not get the consistency I wanted. SDs were just plain lousy. Things started to shape up at 132PF and continued to improve as I upped the speed. At 144PF the SDs were still at 14, so I just gave up.

My go to 180gr minor load gives 139FP with SDs in the 6-7 range. It is super accurate to boot. The best I've been able to do with 165s was SDs in the 10-11 range.

If you are getting high SDs with that load, it may just have been luck that gave you a higher velocity at 80. Did you use the same batch of reloads for each test? How many shots in each string?

It could be load variability. I developed the 3.2gr load a couple of summers ago and it easily made 132PF. I started shooting Production over the winter with said ammo and PF was down around 124PF.

I've since bumped up my .40 minor load to 3.4gr, same OAL, same bullet. I actually set the throw to just a hair below 3.4gr with what seems like +/- .1gr variation. Even with this loading, I got 127PF at 38F and 141PF at 70F. Ammo was sitting in the sun for a few hours when I clocked it at 141PF. That was only 10 shots over the chrono.

Link to comment
Share on other sites

This is intriguing. Let's have some numbers. What is your OAl, and what are your SDs?

I have numbers from when the load went 126.9PF. I don't have numbers from when the 5-10 shots went 140PF as I was practicing with some friends and didn't document the velocity when I got home. Below are the numbers from 126.9PF.

776

821

823

822

815

830

851

798

781

809

777

825

821

829

824

868

851

3.3-3.5gr e3, 155gr Xtreme, 1.125", mixed brass

AVG-818.9

SD-25.467

PF-126.9

Link to comment
Share on other sites

Well, that's an awful string. With an SD of 25 you really cannot "test" for anything, because the wide variations in velocities make any reading a matter of luck. You can prove this to yourself by shooting three separate, consecutive ten shot strings over the chrono. Depending on the luck of the draw, you will probably see a wide variation in SDs. It is even possible, although not likely, you will see three SDs in the teens. If the ammo sorted itself so that a preponderance of the low speed stuff was in the first string, middlin' in the second and higher in the third, you would get three very similar SDs but a wide variation in average velocities.

I was having similar problems when trying to develop light loads in 45ACP. Geez, one string had an SD of almost 41. I tried a variety of fixes. On a tip, I polished the bottom of the powder bar and the track it rides on. It helped a little with consistent drops. Same for polishing the rest of the powder drop system, including the funnel IDs.

Next I improved my chrono technique. It is amazing how much of a difference seemingly minute differences make. To get accurate readings, the bullet must travel straight down the axis, parallel to the plane of the sensors and always at the same height above the sensors. Once I developed procedures to make that always the case, SDs improved quite a bit without any other changes.

However, they were still bad. With 152gr bullets at a 129PF, the best I could do was SD 40.7. Driving them faster and faster improved the SDs. Same thing with 185gr bullets. It's only when I use a slower powder and get over 160PF that I get into the SD10~12 range. With 200gr bulllets (my preferred weight) I can make short range accurate squibb loads, but to get to 50 yard bullseye accurate I have to go above 800fps. My most accurate 50 yards load is 170PF with SDs in the 6~7 range.

I've also found that primers make a difference. WLPs always give me faster and more consistent results in identical loads than CCI 300 primers. I've found the same to be true in 40sw. WSPs are faster and more consistent than CCI500s.

Some or all of these things may be contributing to your lousy SDs. I think the most likely is your 40 (like mine) does not like light, slow bullets. I've completely given up on 155gr. I've had good luck with Xtreme 165gr HP-HPCB bullets ahead of 3.2gr e3. It makes 144PF with an SD of 10.17. It is accurate, but not as accurate as 180gr LTC in my pistol. My best minor load is 2.8gr e3 behind a 180gr LTC bullet for 139PF and SD6.75. It is great for plates and pins, but a touch slower than the 165 for double taps.

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...