N120 temperature sensitivity

[JimSC]

I have been playing with my 30 BW ( 30 Major ) lately using VV N120 and have worked up to 30.3 gns with no pressure signs but I seem to have plateaued at .3 groups. The ambient temperature is dropping into the 30F - 40 F during the days. Summer temps here will be in the mid 90's and come next summer I am worried about pressure spikes with loads developed in the low temps. Since this is my first time working with VV N120 I am wondering what others have experienced with developing a load in cold weather when the temps rise. I am pretty experienced with Varget and H4350 but this VV is a new experience for me. Thanks in advance for any recommendations

 

[joebougard]

I've shot 30.6 of VV120 with 118 Barts here in Georgia, in the 90's with no problems. Slightly compressed load.

 

[jackieschmidt]

Is N120 humidity sensitive like N133?

Quite a few of us who shoot short range group with 133 tune mostly by humidity.

 

[FNSafari]

Have you tried varying your seating depths in your test loads to be on, in and off the lands some? Do you have a tuner on the rifle? Have you used that to try and fine tune your .3" groups?

 

[JimSC]

I bought the rifle last year for shooting 100/200 BR for score but never got around to doing any load development until last week. I will be practicing this winter and plan to shoot it at club level next spring. I guess the smart thing to do is start tuning seating depth, at the moment I am doing a hard jam of .015 with .001 neck tension. I think you are right and I need to play with seating depth first and I need to play with neck tension also, I just got a couple of new mandrels for that.

It's pretty cool here this time of year, but our club only competes in the summer months. I guess I will just have to monitor the FPS over the course of the winter and try and do some tests on the warmer days before competition.

 

[culpeper]

Hogdon has a reloading supplement on this topic. It is on their website. You'll be surprised how insensitive most powders are to temp. I think N140 was like 50 fps 0-125 degreees. Varget was like 8 degrees. Anyway, find the supplement. It is eye opening.

 

[JimSC]

. It is eye opening.

found it and it was indeed, thanks

 

[Ned Ludd]

Hogdon has a reloading supplement on this topic. It is on their website. You'll be surprised how insensitive most powders are to temp. I think N140 was like 50 fps 0-125 degreees. Varget was like 8 degrees. Anyway, find the supplement. It is eye opening.

It's eye opening if one is actually able to obtain the same results as did Hodgdon. Otherwise, it's largely a marketing ploy, as was the term, "Extreme Powders" used by Hodgdon. In my hands, numerous Lot#s of Varget over the years have shown much greater thermal velocity variance than the values Hodgdon claims. The same is true with H4895. I routinely record velocity data at various temperatures and would estimate the variance due to temperature is at least 2-3 times higher than the numbers reported by Hodgdon. The important caveat to that is that Varget and H4895 are still exceedingly good powders with respect to temperature-sensitivity when compared to other powders of similar burn rate. They are both extremely good powders and I use them and love them. Nonetheless, anyone that thinks they're really going to see only an 8 fps change in velocity with a given charge weight over a 40-50 F degree temperature change (let alone 125 degrees F) when using Varget is likely to be very disappointed.

 

[JimSC]

I really did not pay much attention to the Varget/H4350 etc numbers since I have shot them from the mid 20's F to 100F and never had a issue. I try to develop loads that give me a .3 gn or better window, middle nodes when possible. Way at the bottom of that page though was a chart with N140, I am hoping the N120 behaves similarly to N140. Anyway I will play with seating depth and may even pick up a tuner for the rifle. I have a few months to play before next spring

 

[culpeper]

It's eye opening if one is actually able to obtain the same results as did Hodgdon. Otherwise, it's largely a marketing ploy, as was the term, "Extreme Powders" used by Hodgdon. In my hands, numerous Lot#s of Varget over the years have shown much greater thermal velocity variance than the values Hodgdon claims. The same is true with H4895. I routinely record velocity data at various temperatures and would estimate the variance due to temperature is at least 2-3 times higher than the numbers reported by Hodgdon. The important caveat to that is that Varget and H4895 are still exceedingly good powders with respect to temperature-sensitivity when compared to other powders of similar burn rate. They are both extremely good powders and I use them and love them. Nonetheless, anyone that thinks they're really going to see only an 8 fps change in velocity with a given charge weight over a 40-50 F degree temperature change (let alone 125 degrees F) when using Varget is likely to be very disappointed.

I usually don't see any material difference considering other factors that get lost in the noise from one shooting session to another. It is not uncommon for my zero to shift .1 mil or so. Could be the temps could be other factors mixed together. I do agree the Hogdon claims are in a vacuum but I also don't see a material difference with single based VV or Accurate. I just don't shoot that good and a proven .75 moa rifle is good enough for my purposes. Not enough accuracy for me to worry about temps in my experience. I'm seeing on average about .3 fps per degree single based Hogdon and about twice that much for VV and Accurate single based powders. Makes it hard for me see any material difference out to 600 yards all things else considered and a quick minor adjustment for precision. Unless it is one of those days where it is so cold my hands and fingers feel like needles are stuck in them and getting beat with a hammer. Damn thing about shooting is we have to sit still no matter the temp. The inner and outer fringes of cold and hot is where knowing powder sensitivity makes a difference if there is no opportunity to zero and validate at distance. That and Tier 1 competition shooters.

 

[Larry Koch]

I have been playing with my 30 BW ( 30 Major ) lately using VV N120 and have worked up to 30.3 gns with no pressure signs but I seem to have plateaued at .3 groups. The ambient temperature is dropping into the 30F - 40 F during the days. Summer temps here will be in the mid 90's and come next summer I am worried about pressure spikes with loads developed in the low temps. Since this is my first time working with VV N120 I am wondering what others have experienced with developing a load in cold weather when the temps rise. I am pretty experienced with Varget and H4350 but this VV is a new experience for me. Thanks in advance for any recommendations

What bullet weight? What year of vvn120?? I think you can go up a whole grain to 31.3 and still be good in the heat of summer.

 

[JimSC]

What bullet weight? What year of vvn120?? I think you can go up a whole grain to 31.3 and still be good in the heat of summer.

115 Bergers, VV N120 is dated 12.01.2018

 

[Larry Koch]

I use 31.3 v 120 115 grains bergers with Federal Primer 205m in the 30 Major with out issues. And a few tenths more in cooler weather. 3040 fps 26" barrel