New vs Old Vihtavuori N140 Temperature Sensitivity for .223 Remington

[BillC79]

As part of a study on temperature sensitivities of powders for .223 Wylde high power service rifles, I had a chance to compare old and new Vihtavuori N140 under the same conditions. Since I was unable to find data on the new N140, I am posting mine here for more easy access in online searches. Apologies to the forum editor if double posting of the same data on the forum is prohibited.
The link to the full study in progress is below and is being discussed in a separate thread on this forum:

Temperature Sensitivity of Powders for .223 High Power Service Rifle

The newer N140 is reported (and advertised) to be “Temperature-stable” and to contain a “Decoppering agent.”
The new N140 appears to be less temperature sensitive below 68°F (20°C) than the old in the temperature range I tested. New N140 produces significantly higher velocity than the old at the same case charge with a 77 grain bullet. Both the new and the old N140 are moderately temperature sensitive above 68°F compared to Varget. With a case powder charge of 24.3 grains, both the old and the new N140 at 129°F (54°C) produce overpressure signs on primers (primers flattened and partially extruded from the primer pocket).


*p<0.05 Significant temperature-induced increase in muzzle velocity, one-way ANOVA, Holm-Sidak multiple comparison.
There is also a significantly higher velocity (p<0.05) with new N140 by two-way ANOVA and Holm-Sidak multiple comparison.



New Vihtavuori N140 on the left (Lot# 02.06.2021) and Old N140 on the right ( Lot# 01.12.2017)

 

[dhagerty40]

You just confirmed a suspicion I have had for a while but i am loading in the 6BR, 6.5x47L and 7-08. I had to drop anywhere from 1-3 grs to get back to same specs on my loads.

 

[Kiwi Palma]

Never had too much issue with temperature sensitivity with either 2208/Varget or N140 here in NZ in the .308 Palma loads - even in Gisbounes 30+ summer scorcher when accidentally left out in the sun. Still safe and yes the velocities did go up on both but still a safe load to use and both stayed about the same for grouping and ES/SD figures.
With VV N140 now become unobtainium here, having to ration the use to critical competition use only - especially if making the 2028 Palma trip. But good to know that the new N140 is actually different to the older lots with higher velocities being achieved seeings as that version was received in the last shipment and the old version since the main 1993 lot I got, all six lots developed the exact same load data.

Now to work out how ADI/IMR8208 compares - that is a lot easier to aquire and appears to be close to the VV N140 load than ADI2208/Hodgen Varget - including its price!

 

[CF Junkie]

Old VV ratings were rated at 100 fps increase between 0 deg F and 125 degrees F.
Your data seems to confirm that.

Varget was rated at 4 fps for .308s and 8 fps for .223s. That also seems like it confirms your data.

Haven't measured the new N140 or N540 powders for temperature stability over temperature, but, in my .223 bolt action target rifles shot from a bench with a F-class bipod and rear rest, the new N540 performs slightly better than the new N140 by about 0.040 average group size but both average under 0.290 for all the loads shot. My results are based upon Optimum Bullet time loads so they are all loaded for the same bullet Exit Times but the N540 powder loads produce about 20 fps faster average MVs with the same ETs.

 

[SeabeeKen]

According to VV, N-540 is more temp stable then N-140. I was surprised that a double base could be more T stable. This video was posted just over a week ago.

 

[LCazador]

Great information that parallels my tests. Thanks.

 

[RegionRat]

According to VV, N-540 is more temp stable then N-140. I was surprised that a double base could be more T stable. This video was posted just over a week ago.

Agree, I was a little surprised by that video as well but will take a wait and see position.

Chemists can sometimes produce magic.

If they managed to "flatten the curve" for a 500 series and get it to the levels of the 100 series, they are to be commended.

Now I am wondering if they actually re-wrote the play book across the boards, or if it gets real specific to a particular cartridge-use case? Time will tell.

 

[NZ_Fclass]

Never had too much issue with temperature sensitivity with either 2208/Varget or N140 here in NZ in the .308 Palma loads - even in Gisbounes 30+ summer scorcher when accidentally left out in the sun. Still safe and yes the velocities did go up on both but still a safe load to use and both stayed about the same for grouping and ES/SD figures.
With VV N140 now become unobtainium here, having to ration the use to critical competition use only - especially if making the 2028 Palma trip. But good to know that the new N140 is actually different to the older lots with higher velocities being achieved seeings as that version was received in the last shipment and the old version since the main 1993 lot I got, all six lots developed the exact same load data.

Now to work out how ADI/IMR8208 compares - that is a lot easier to aquire and appears to be close to the VV N140 load than ADI2208/Hodgen Varget - including its price!

As Kiwi Palma said - VV Powders have been difficult to obtain - and high prices demanded for a while. But just to mention - N140 is much closer in burn rate to 2206H/H4895 than 2208/Varget. Both produce great loads in the 308 - especially with 155g pills. IMR8208 is also quicker than Varget - loads around 44g produce good velocity. 8208 is also a good choice for 223 - I will be also testing it alongside 2206H for my 6BR shortly, as I have a few Kilos put aside. I'm guessing (at this point) that 8208 is temperature stable, as it is used in Aussie military 223, according to a knowledgeable source. (Having said that...those of a certain age will remember AR2201, also used by the Aussies, that was the most temperature unstable powder ever and probable bent a few Omarks and FN SLR's in its time...)

Thankfully, ADI powders are available to us and we do have enough choice without resorting to Unobtainium (VV) or Overpriceium (Alliant).

 

[charlie b]

I like that 'Overpriceium'

I've been able to get N140 and N540 easier than the alternatives. Haven't seen Varget or 4895 on a shelf for a couple years now but I can usually find one of the VV powders. A bit more expensive, but, so are Bergers