V320 temperature sensitive?

[MilkMyDuds]

I loaded a few thousands rounds in hot Texas summer when I first got V320. I chronoed them under 98-100F temperature and got avg 880fps (10 rounds) with a decent standard deviation of 7.5.

Now a few months passed, and temperature has dropped significantly. I took some of those rounds and chronoed them again under 60F with the same chronograph. The avg now is 860fps with a 8.8 standard deviation for 10 rounds. This renders all these rounds useless for major matches (assuming the matches are 60F weather) because it is too close to the PF floor.

Is this normal? I thought V320 is less temperature sensitive than Titegroup and other powders?

[9x45]

Changes in barometric pressure, ambient air temperature and relative humidity cause the air density to change, and therefore the measured muzzle velocity. So if you live in Florida, and check your loads at sea level, 100F and 85% RH, you can expect greatly different results when shooting a match in Denver at 5,500 ft, 55F and 25%RH. That's why you always load 5% or so above the floor...... It sucks to drop from major to minor, but it sucks more to fail minor. Shooting a match for no score is not fun, so drop in a couple more tenths of powder.

Here is an interesting read.

http://riflebarrels.com/ballistic-effects-of-altitude-temperature-and-humidity/

[a matt]

To me down in the South VV powders are not very temp sensitive. This is from 3 years of soothing only N320 & 3n38 this last year.

But like 9x45 pointed out, still lots of variables

[CZinSC]

I've been using N320 for several years, and i've noticed when the temps get down to 30-40 degrees in the winter, i lose about 10-20 fps.

[LilBunniFuFu]

Down in Florida it's always hot so I have never had a problem with N320 being sensitive. But most of the state is at or barely above sea level. temps range from 60-100 F. I keep my load between 130-135 just to be sure.

[Service Desk]

In my experience N320 is slower the colder it gets.

[Red Ryder]

I have noticed no temp related deviations of any significance. 20 degrees to 95 degrees.

Edited November 7, 2015 by Red Ryder

[Isurg]

I chrono'd N320 at 30 degrees and got about 20-30fps less than my loads during the summer

[Red Ryder]

I chrono'd N320 at 30 degrees and got about 20-30fps less than my loads during the summer

Did you shoot 20+ shot strings? Were the Standard deviation, extreme spread, and Power Factor, same as your warm weather results? I have loaded 10s of thousands of 9mm minor rounds and have found no temp sensitivity or Lot# to Lot# differences. Maybe I am doing something wrong? 3.6 Grains of N320 with a Montana Gold 147 grain CMJ loaded at 1.132 with CCI small pistol primers has chronoed at 6 major matches at a 131.2 to a 131.6 PF for 3 years. All the brass is the same head stamp, RP brass, and has been roll sized with my Casepro100. My OAL deviation is +/- 0.002. Standard deviation across the chrono is 5. I may not shoot fast enough, but I reload very well. You want to reproduce my results? Use a tool head clamp kit on a Dillon 650, EGW Udie, Redding competition seater and crimp dies, and reload slowly with consistent complete motion. Winchester small pistol primers or CCI, it didn't matter. Glock 34. 129 PF in an STI EDGE 9mm this year.

Edited November 17, 2015 by Red Ryder

[MilkMyDuds]

Not sure if the "tool head clamp kit" is a good idea... I contemplated getting it for my 650 that seems to have some play between the toolhead and the machine, but after reading the following I gave that idea up.

The interesting thing is, UniqueTek also offers a "floating toolhead" that is said to move around for best concentricity during seating. Not clear why they offer products with totally conflicting concepts. Maybe the optimal approach is to fix solid some dies but let others float around?

One big difference between your loads and mine is that I use coated bullets. Maybe the powder is not the reason, but the coating of the bullets makes the difference?

Posted: 12/31/2011 2:22:57 PM EST

I considered one but called Gary at Dillon and asked him about it. He said that they specifically designed the presses so the toolhead floats to allow for a smoother reloading process and that he didn't recommend one at all.

Something to consider.

[Red Ryder]

Tool head clamp kit reduced my OAL variation significantly with no other ill affects.

[rancher5]

I chrono'd N320 at 30 degrees and got about 20-30fps less than my loads during the summer

Did you shoot 20+ shot strings? Were the Standard deviation, extreme spread, and Power Factor, same as your warm weather results? I have loaded 10s of thousands of 9mm minor rounds and have found no temp sensitivity or Lot# to Lot# differences. Maybe I am doing something wrong? 3.6 Grains of N320 with a Montana Gold 147 grain CMJ loaded at 1.132 with CCI small pistol primers has chronoed at 6 major matches at a 131.2 to a 131.6 PF for 3 years. All the brass is the same head stamp, RP brass, and has been roll sized with my Casepro100. My OAL deviation is +/- 0.002. Standard deviation across the chrono is 5. I may not shoot fast enough, but I reload very well. You want to reproduce my results? Use a tool head clamp kit on a Dillon 650, EGW Udie, Redding competition seater and crimp dies, and reload slowly with consistent complete motion. Winchester small pistol primers or CCI, it didn't matter. Glock 34. 129 PF in an STI EDGE 9mm this year.

Interesting I shot thousands Blue Bullets 147rn actual bullet weight is 149ish anyway use 3.2 gr N320 PF 151 I've backed off to 3.0 grains Blue Bullets tend to always give me 80+ fps over plated ,jacketed ect, shows chrono'ing is very important for load development ,shot w/CZ TS 9mm

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[Red Ryder]

I use 3.2 grains of N320 with 147 gr Bayou Bullets. OAL 1.135. 132 PF in my G34.