VV N140 temp sensitivity

[Dave M.]

Per the charts I have read, N140 is rated at 0.4fps/1deg F. However, my most recent testing was quite the contrary. My reloading room is very consistently held at 60F and 46% RH.

Shot on 2/4/24 at 28F / 93% RH / 29.416” Hg in my 6 dasher with 33.2gr of N140 and CBTO of 1.737” (Jam + 5K) muzzle velocities after 10 fouler/sighter shots:
10 shots with an average MV of 3006fps (ES 11fps, SD 2.8fps)

All brass was annealed after firing and the brass was processed in the exact same manner. 0.0005” shoulder bumped, same .265 SAC bushing, same primer batch, same seating depth, and all other processing steps identical.

Shot on 3/2/24 at 48F / 62% RH / 29.402” Hg in my 6 dasher with 33.2gr of N140 and CBTO of 1.737” (Jam + 5K) muzzle velocities after 10 fouler/sighter shots taken to warm rifle:
10 shots with an average MV of 3042fps (ES 18fps, SD 4.6fps)

If N140 (from the same 8lb jug), has an advertised temp sensitivity of 0.4fps/1 deg F and the temperature went up 20F, the resultant velocity should have went up approx 8fps. My testing shows this isn’t the case. I expected to see the initial 3006fps to go up to approximately 3014fps. It actually went up to 3042fps. This equates to 1.8fps/1 deg F, which is even worse than RL-15 which I find to be between 1.4-1.6fps/1 deg F.

Curious of others findings with N140.

Dave M.

 

[Ajwilly96]

Just curious, is this a newer jug or older jug of N140?

 

[Keith Glasscock]

If it's any comfort, I get around 1.4 fps/deg F change in velocity in both my 308 and 6 Dasher. This is fresh powder, less than year old, and using rounds that were loaded all at the same time.

Definitely not 0.4

YMMV

 

[hoz53]

Per the charts I have read, N140 is rated at 0.4fps/1deg F. However, my most recent testing was quite the contrary. My reloading room is very consistently held at 60F and 46% RH.

Shot on 2/4/24 at 28F / 93% RH / 29.416” Hg in my 6 dasher with 33.2gr of N140 and CBTO of 1.737” (Jam + 5K) muzzle velocities after 10 fouler/sighter shots:
10 shots with an average MV of 3006fps (ES 11fps, SD 2.8fps)

All brass was annealed after firing and the brass was processed in the exact same manner. 0.0005” shoulder bumped, same .265 SAC bushing, same primer batch, same seating depth, and all other processing steps identical.

Shot on 3/2/24 at 48F / 62% RH / 29.402” Hg in my 6 dasher with 33.2gr of N140 and CBTO of 1.737” (Jam + 5K) muzzle velocities after 10 fouler/sighter shots taken to warm rifle:
10 shots with an average MV of 3042fps (ES 18fps, SD 4.6fps)

If N140 (from the same 8lb jug), has an advertised temp sensitivity of 0.4fps/1 deg F and the temperature went up 20F, the resultant velocity should have went up approx 8fps. My testing shows this isn’t the case. I expected to see the initial 3006fps to go up to approximately 3014fps. It actually went up to 3042fps. This equates to 1.8fps/1 deg F, which is even worse than RL-15 which I find to be between 1.4-1.6fps/1 deg F.

Curious of others findings with N140.

Dave M.

thats interesting— I think I will do my own test and report back in a few months. Thanks for the info.

 

[JFrank]

@Dave M.
Are you seeing the accuracy drop off or the node moving ?

 

[Cfshooter]

Hard to tell since they were loaded at a different time with brass prepped in a different session. But Keith noticed 1.4 with all else the same so……

 

[Dave M.]

@Dave M.
Are you seeing the accuracy drop off or the node moving ?

Both shot incredibly small even though the Avg velocity had a large shift. I’ll send pictures when I get home tonight.
Dave

 

[Dave M.]

If it's any comfort, I get around 1.4 fps/deg F change in velocity in both my 308 and 6 Dasher. This is fresh powder, less than year old, and using rounds that were loaded all at the same time.

Definitely not 0.4

YMMV

This is almost what I see as well

 

[Dave M.]

This is the chart that the 0.4 appears on

 

[Dave M.]

Just curious, is this a newer jug or older jug of N140?

Actually it started out as a brand new sealed jug on 2/4/24 and then I reloaded again on 2/26/24 for my range session yesterday. Viht controls their powder packaging at 45% RH and I keep close tabs on my reloading room and for the last 4 months straight it has not deviated 45% RH humidity by more than 4% in either direction. I also record the RH every time I reload and the first session it was 46% and the second session it was 44%, so nearly identical.
I like the idea of loading several identical rounds at once and then shooting them at various temps. I can actually do this using yesterday’s data because I still have 16 rounds remaining from the range session that match all parameters exactly. This would take the data from session one out of the mix.
Dave

 

[JFrank]

Both shot incredibly small even though the Avg velocity had a large shift. I’ll send pictures when I get home tonight.
Dave

Good to hear, the one lot I’m working with now is actually from 2014 while my newest is 2023. I’ll keep my eye on them both.
Thanks
Jim

 

[Dave M.]

Good to hear, the one lot I’m working with now is actually from 2014 while my newest is 2023. I’ll keep my eye on them both.
Thanks
Jim

Here are a 4 shot and a 3 shot group from 100 yards shot in anything but still conditions.
Shot on 2/4/24 (weather and reloading conditions located above in previous post):


Shot on 3/2/24 (weather and reloading conditions located above in previous post):

Shot on 3/2/24 (weather and reloading conditions located above in previous post), this a 5 shot group fired at 100 yards .005” longer CBTO than the picture above:


Dave

 

[JFrank]

Do you have any follow up data from a little more distance to the target ?

 

[Dimner]

If it's any help, of the powders that have values on that chart, every powder I have personally tested has been far worse.

0.73 for IMR 3031 is way off
Benchmark, H4895, and H4350 are about 50-75% higher than noted in the chart.

Ramshot Hunter at 0.86 is absolutely laughable. It's super temp sensitive in my 7x57 Tikka.

I wish I could find accurate information, but I ended up having to stop paying attention to charts like that. Now I just make sure that I have tuned and tested at likely temps I know I'll shoot in. Recreational loads, 50-85 degrees. Hunting loads 55 to 25 degrees. I don't compete thank goodness and don't have to worry about shooting in temps where I would rather be doing something else.

if I did compete, i would lean on and learn a barrel tuner even if it took 1000 rounds to get the process down.

 

[Dave M.]

Do you have any follow up data from a little more distance to the target ?

Not yet because I haven’t been able to take it out to 600 yards yet, but the 100 yard groups look promising. My main concern is the instability of the N140 powder which I was always told is very temp stable (certainly not my finding nor those of a few other members using this powder.) I can tell you the N140 cleaned like a dream, but in all fairness, I’m used to cleaning RL-15, which is by far the dirtiest powder I shoot.
Dave

 

[Dave M.]

If it's any help, of the powders that have values on that chart, every powder I have personally tested has been far worse.

0.73 for IMR 3031 is way off
Benchmark, H4895, and H4350 are about 50-75% higher than noted in the chart.

Ramshot Hunter at 0.86 is absolutely laughable. It's super temp sensitive in my 7x57 Tikka.

I wish I could find accurate information, but I ended up having to stop paying attention to charts like that. Now I just make sure that I have tuned and tested at likely temps I know I'll shoot in. Recreational loads, 50-85 degrees. Hunting loads 55 to 25 degrees. I don't compete thank goodness and don't have to worry about shooting in temps where I would rather be doing something else.

if I did compete, i would lean on and learn a barrel tuner even if it took 1000 rounds to get the process down.

It seems you are spot on. I just got excited to try a temp stable powder for a change. Seems like they might be like unicorns.

 

[JFrank]

Well I’m about ready to re-test from my previous -0- to 10 degrees at 500 yards to around 40 degrees, I have chrono numbers to compare although I’m not hung up on numbers I’d rather follow the target.

 

[JFrank]

Today I small sample tested again in 53 degrees temperatures.
N140 /300 yards R-L 5-7 hum 46%

Today 31.6 avr 2897 \___12 fps
Zero - 31.6 avr 2885 /

 

[Dimner]

Am I reading that wrong? 0F to 53 degrees! 12fps increase? You sir, have the holy grail lot! I hope my 2023 lot does the same. Cannot wait to try it.

And I get what you are saying about following the target results over getting too worried about FPS. For me I guess the fps is a mental thing. It sits there in the back of my mind. I need to let some variables go. Or like you say trust the target. And I can do that by running the test over and over again until I build that trust. I think that's what I'm gonna be doing this spring!

 

[Dave M.]

12fps over 53F temp swing, is incredible. My results are not in line with that at all and neither are the results of some of the other posters that commented on my original testing.
Dave