VV N 560 Temp stability

[Dubious]

Has anyone collected any data on how temperature swings effect vv n560 powder? I’m having really good luck with it in my 25-06ai and 300wm. The 300 I’ve got a stable no issue load to 3050fps using Berger 210 vldh but I’m close to where the bolt starts to get sticky at 3100 FPS I’ll probably continue to develop that load around 3000 to be safe leaving a bit of a buffer. With the 25 I’ve haven’t found pressure yet but I must be close @ 3350 FPS with a 115gr Berger vldh using h4813 in the past that’s about the speed where I started to see issues on the brass.

[marky_mark]

Originally Posted by Dubious

Has anyone collected any data on how temperature swings effect vv n560 powder? I’m having really good luck with it in my 25-06ai and 300wm. The 300 I’ve got a stable no issue load to 3050fps using Berger 210 vldh but I’m close to where the bolt starts to get sticky at 3100 FPS I’ll probably continue to develop that load around 3000 to be safe leaving a bit of a buffer. With the 25 I’ve haven’t found pressure yet but I must be close @ 3350 FPS with a 115gr Berger vldh using h4813 in the past that’s about the speed where I started to see issues on the brass.

Thats cookin!

[Dubious]

Originally Posted by marky_mark

Thats cookin!

Ya this is a my latest quick load project the n560 was near the top of the list for these bullet caliber combos and it just happened to be in stock at Flys etc. The goal it to develop a fast stable safe readily available off the shelf high B.C. single loading round for knocking on the gong out at the ranch. This won’t be a hunting load the col is excessively out of the mag.

[marky_mark]

Originally Posted by Dubious

Ya this is a my latest quick load project the n560 was near the top of the list for these bullet caliber combos and it just happened to be in stock at Flys etc. The goal it to develop a fast stable safe readily available off the shelf high B.C. single loading round for knocking on the gong out at the ranch. This won’t be a hunting load the col is excessively out of the mag.

I have some n565 and n570 for my 338 lapua
Ive decided to single feed it for long range accuracy and develop a second load for a frames or something like that for in close like 400yards or less

[Dean2]

Originally Posted by marky_mark

Thats cookin!

Yes it is. With those kinds of speeds temp stability isn't the biggest worry. Those are far over any published load velocities for the 300 WM, in fact those are at or just over 300 RUM speeds. You may not be seeing pressure signs but speed equals pressure so I would suggest you want to back the loads off another 150 fps. Your gun, your choice, but I wouldn't be shooting loads that hot even on cold days.

[Dubious]

Originally Posted by Dean2

Yes it is. With those kinds of speeds temp stability isn't the biggest worry. Those are far over any published load velocities for the 300 WM, in fact those are at or just over 300 RUM speeds. You may not be seeing pressure signs but speed equals pressure so I would suggest you want to back the loads off another 150 fps. Your gun, your choice, but I wouldn't be shooting loads that hot even on cold days.

these loads have been dropped 150 fps already. 3100fps is in excess and was the extreme end of testing and won't be used.

[Dean2]

Originally Posted by Dubious

these loads have been dropped 150 fps already. 3100fps is in excess and was the extreme end of testing and won't be used.

Smart move and good to hear. Let us know what your temp testing shows in terms of velocity variation as the temperature changes. Most Nitro added powder like N560 tend to be less temp stable than those without it so be interesting to see what you find.

[Dubious]

Originally Posted by Dean2

Smart move and good to hear. Let us know what your temp testing shows in terms of velocity variation as the temperature changes. Most Nitro added powder like N560 tend to be less temp stable than those without it so be interesting to see what you find.

there seems to be mixed feeling about this powder some reports are saying its very stable other not so much the data I collected yesterday it was -8º I guess ill have to wait for a warmer day and shoot the same load and get an average I didn't collect any ES or StD data as these loads where one offs looking for plateaus.

[Dean2]

For a bunch of fairly complicated reasons Nitro powders tend to be fairly stable at 50F to 100F but less stable as the temperature drops and particularly below 20 F. The velocity change per degree usually increases again after -10. I have never temp test N560, so not sure if it will show the same pattern as other Nitro powders.

[Dubious]

Thanks dean I appreciate the help. How did you test in the past just warm day cold day?

[Dean2]

Pretty much. I keep detailed records of loads, velocities, SD, ES but I don't always shoot thorough a Chronograph, especially at longer distances, so the most important is elevation or dial up at longer ranges. You can convert the elevation differences into velocity pretty easily, though you do have to record and account for elevation, humidity and pressure to be really accurate.. I used to target shoot pretty much year round so over a couple of years a guy got some pretty good data on the rifles I shot targets with a lot.

[Dubious]

I also shoot year round and collect a lot of data. I record speed for each shot in a string average speed min and max speeds ES StD date temp pressure and location of range. Haven’t accounted for altitude but I only shoot at 2 ranges so it wouldn’t be hard to figure out. This powder I haven’t used before so I Only have 30 shots worth of data

[waldedw]

I've got some test loads loaded up now with N560 behind a 190 gr nosler accubond long range in my 300 RUM, have not shot them yet, had hoped to this week but the cold and wind every day changed my mind

[Dubious]

-6° avr (5rnd) 3343
-1° avr (15 rnd) 3347
+6° avr (15 rnd) 3381

*Temperatures taken from weather network app and may not be accurate to range conditions

*Velocity recorded with LabRadar.

[Dean2]

Originally Posted by Dubious

-6° avr (5rnd) 3343
-1° avr (15 rnd) 3347
+6° avr (15 rnd) 3381

*Temperatures taken from weather network app and may not be accurate to range conditions

*Velocity recorded with LabRadar.

That seems about right, averaging 3.3 FPS per degree, which is actually quite a lot and not what I call temp stable. I bet once you get to try this same test at 15-25 C you will see a much smaller FPS difference per degree, I would expect it to get down around 1-1.3 FPS.

[Dubious]

I’ll be trying 4831sc I have a load developed and hear it it much more temp stable. I would like to test 5 more with the n560 and a bore that has been treated with wipe out the high speeds on the last test set where unexpected with the groups falling apart. Would be interesting to see if that effects the velocity aswell as the std I have been playing with in the other thread.