We seem to have a lot of posts asking about temp sensative powders. I suspect we're making far far too much of an issue here and wonder if others agree.

The only time I got into trouble with temp sensitive powders was when I was shooting prairie dogs on a 106 degree day.....and then when I would load a round into a hot chamber and let it simmer there a bit until I shot it. Further I had the rounds loaded to max and possibly a bit more.

The other time was when I had left ammo in a box on the dashboard and the sun baked it to temps so hot it was hard to hold in the hand.

These things happened thirty years ago and I was told to keep the ammo in a cooler.....and I learned fast.

There was no serious loss except for a few sticky bolts.

I've never had a problem hunting in the cold and I've hunted to -20 F.....

So what say you.....are we going off the deep end with temp sensitivity?

Yep....another one of those drum beatin, turd polishin non-problems that is a problem. I hunt all over CO from the top of the mountains in freezing temps to the summer prairie at three digits. It has never been a problem for me. If you hunt in conditions that fall outside of that range you are at some miniscule risk of a temp sensitive problem.

I use alot of RL-22 which is supposed to be one of the temperature sensitive powders. I don't own a chrony so I really can't tell what the real difference velocity might be. But what I can say is that all of my loads this year were worked up in the late summer/early fall where the temps were probably in the mid 70's to mid 80's. My last deer was shot the morning after Thanksgiving and if I recall correctly the temps were in the -10's. I didn't notice any difference in where my shots were going.

I use temperature-insensitive powders when I can get them, and I almost always can. I spend entirely too much time tweaking a load with a half-grain of powder here and 0.005" seating depth there to want to have the effect mucked up with a temperature change. John Barsness cited a 200 fps velocity change, IIRC, on some loads put together at 70F and fired at 30F.

It seems to me that the half-grain of powder is to tune the barrel harmonics to an optimum based on a certain velocity. Why would we expect the point of impact to remain unchanged if the velocity changes the equivalent of four or five grains because of cold?

Another reason I like insensitive powders is that some of my load tweaking takes place in the heat - not just ambient temperature, but from a heated barrel and receiver. I prefer to take advantage of the technology when I can.

Jaywalker

I have shot the same loads that were max for my rifle's in temperatures ranging from -20 to 80F and never noticed any difference. But I never ran them across the chrono either. It didnt matter to me as along as they shot to the same point

I built up this real nice accurate load when it was 5F outside with RL22. Then I went that summer at about 75F and shot and locked the brass in my chamber. so I figure I was on the edge in the winter. Other than that, I see some loads that are not very accurate in the summer as they are winter.

I guess I have taken the bait hook line and sinker on temp senitive powders too, I hate to admit. As I try to use it when I can. But still use all the IMR powders.

I just wonder if H1000 would have reacted the same as teh RL22.

I used to load IMR 4350 for my 30-06 and shoot in the cold weather to work up accurate loads. If I shot the same load during the summer it was to hot.
Solution would be to work up a load while it is so hot outside that you can fry an egg on the sidewalk then it should be fine during the winter, or you can buy the powder that is not temp sensitive and save your self some grief.

Working up a load with RL22 for the 300 win mag or RL19 for the 338 win mag here in Houston is definitely never the same as when I go hunting in Colorado in November. However, I figure that the loss in velocity due to temperature is mitigated or cancelled by the increase in velocity due to elevation.

My 300 win mag load shot exactly where it was supposed to last year at 7500' altitude at 35 degrees.

ALL reactions are starting temp sensitive...
"how long does it take to make ice cubes"
depends on the initial temp

how fast with X powder go with Y bullet

depends on the temp

doesn't matter if it's endo or exothermic...

jeffe

quote:

I see some loads that are not very accurate in the summer as they are winter.

Very true, I've seen that w/ several loads. I try to develope my hunting loads in the spring if I can because the temps are similar to the fall.

Just rescently I had a little problem w/ H4831, the loads developed in the hot summer last year that shot tight groups consistently didn't do well in the cooler temps this spring. I bumped up .5 grains and got it right back where it was last summer. I believe I'll have to drop that .5 grains off in another month when the temps rise.

I've seen it w/ R22 as well.

Reloader

I don`t think the differance in powder temp is in the velocity change at various temps as it is pressure. You can change the pressures quite a bit and not note a large change in velocity in the load, especially if there is a fairly large extreem spread in the load to start with. The problem arises IMO when we take a load developed at 30 F and then shoot it at 85F finding accuracy and velocity appear normal but, pressures are sticking the bolt.

I haven`t noticed much change in accuracy with a load that shoots well at say 80 F and then shooting it at 10-15 F. I have seen a change in velocity however with some powders, although usually small say 75 fps. The powder that shows some velocity variation in my `06 may, or may not, show one in my 6.5 swede. Powders don`t seem act the same in all cartridges.

Most variation in my limited experiance seems to come in higher temps, not falling. The change from 60F to 90F will show more change in the load then a change from 30F to 70F.

As far as the change in velocity affecting the load for hunting. The Nosler 30 cal 180 gr BT with a 3100 fps velocity will drop 0.3" less then with a 3000 fps vel at 200 yds with a 100 yd sight in, and 0.9" less at 300. Double check the POI before the hunt to insure your scope wasn`t bumped and go.

I think way too much is made of this largely self-inflicted problem. It would be unreasonable not to expect problems when one is operating on the ragged edge, no?

While we are talking about temps. How is accuracy affected by other weather variables, like humidity, air density, and the like.

Because some of what is being blamed on temperature could possibly be the fault of other weather variables. of course that might only effect things at longer ranges.

The only time I've seen problems with fluctuation due to temperature is with ammunition originally loaded for my Mini-14 with H335 (and CCI Magnum primers) and a 55gr FMJ-BT
when I fired that ammunition in my shiny new Rem700VSSF in 223Rem

Major vertical stringing, as much as 4-6" at 250yards

the first shot from a cold barrel result in a fired case with a "high" primer.

If I fired two quick shots into the backstop then let the third
sit in the barrel for 60 seconds to warm up or so I could put a series of "3rd shots" into 3/8" at 100yards.

I could also group the first and second shots consistantly(on their own targets at a different point of impact)
So the ammo itself was consistant if all fired at the same temp.

I saw no issues with the same bullet/case-prep/primer
when loaded with RL7.

Ambient air temp was around 20'F and I doubt I would have experienced the same phenomena at 85deg ambient.


AllanD