Humidity

[Dixie Dude]

Does humidity affect reloading?  I live in the deep south.  It is hot and humid in the summers, and sometimes cold and humid in the winter.  I will be reloading inside with central heat and air.  Humidity inside is running about 30-50% in the winter.  Haven't checked the summer yet.  Where I hunt here it is sometimes in the 20's F to the 60's F.  However, I would like to hunt out west and Alaska, and then Africa the first few years of my retirement.  I plan on early retirement sometimes within the next 3-5 years.  Thanks

[Questor]

It does with some powders. I have a big swing in humidity from summer to winter and notice with some powders, like bullseye, that charge weight varies with the humidity. I haven't found the difference to be significant with my guns.

[clodbuster]

My experience has been that temperature has a lot more to to with pressure and velocity than does humidity.  If you have a load that is say just below max at your high summer temps down yonder and then take it north in the winter and you'll see a big drop off in velocity.  I've had them that you could tell just by recoil and boom differences.

[Dixie Dude]

My reloading room is inside my house with central heat and air.  So, if I reload at 70 degrees, it would be a higher temperature in Africa and thus higher pressure and velocity, but in Alaska, it would still be lower pressure and velocity?  If I'm planning a trip to Africa, I need to reload in the summer.  If I plan to hunt Alaska, I need to turn my heat down to say 60 and reload, right? 

[stimpylu32]

Dixie Dude

The temp you load at is not going to make much of a diffrence as far as velocities goes , what you need to do is find a load that shoots well at the temp you are going to be hunting at .

A load that shoots well at 60 will have a much higher pressure at say 100 , but a load that shot well at 100 will stand a good chance of being slower and having a diffrent point of aim at 30 .

Last year i took a load in .223 to a P-dog shoot that shot very well at 100 the year before and tried to shoot it at 70 but the POI was 2" lower @ 100 yards .

stimpy

[Dixie Dude]

I did not know this.  What temperature do the manufacturers make their cartridges?  Most all of my hunting down here is done from mid-November to January.  Probably an average of 30 degrees.  So I need to reload as cool as possible.  From what I have read about Africa, temperatures can range from around freezing at night to mid-80s in mid-afternoons during the summer hunting seasons in South Africa.  So reloading for Africa's average daytime temperature shouldn't be a problem.  However don't really know what the average would be in Alaska, but probably like our winter average of 30.  This is interesting. 

[corbanzo]

As long as you keep your powders closed and stored properly, the small exposure that they do have to humidity shouldn't make too much of a difference.

Many manufacturers will give the temperature and elevation of where their loads are tested.

I'm not sure exactly at what of each that which manufacturer does their testing, but I can tell you this:  they do it warm and high as they can.

The reason is that the warmer it is, and higher it is, the thinner the air and better the ballistics will look.  From what I can remember...  I have seen a few at 2,000ft at around 65 degrees or so... but don't quote me on that.

But yes, match load to your hunting temps. 



And speaking of the boom....  try and go bird hunting with your buddies in ice fog...  big boom, lots of reverb off the fog.  almost eerie.

[AtlLaw]

<snip>  So I need to reload as cool as possible.  <snip>

If I'm understanding you correctly, You are assuming you need to actually LOAD your ammunition at a comparable temperature to that in which you plan to SHOOT the rounds.     If this is the case, I think you may be a little off base here, but I've been wrong before.

I don't think it makes much difference what the temperature is when you are actually LOADING your ammunition.  That variable comes into play in the interrelated areas of pressure, POI, velocity and such as that.  My hand load development form has a box for me to record the OAT at the range when I am shooting, but I think, for the average hunter/shooter, that OAT has about as much relevance as the number of feet above sea level does nowadays.

I also shoot a lot of "extreme" powders.

I'm in No. Metro Atlanta and keep my gun/reloading room at about the same humidity level as you do.  No rust or mildew and my propellants don't usually stay around long enough to be effected even if they would be! 

[beemanbeme]

I did a lot of reloading in Memphis.  In my garage, temp 100degs, humidity 100%.  I'd take the ammo to Colorado/ Wyoming and it seemed to kill stuff pretty good.  I always verified my zero once I was there and I would attribute any 1" variance to a difference in altitude or whatever.  while I was loading up big game ammo, I was also loading up a whole bunch of Pdog ammo. Over the years, I've killed a lot of Pdogs.  I never verified zero with my Pdog rifles, I just pulled them out and started killing Pdogs.  I never Chronied my ammo in Memphis in the summer and then Chronied it in Wyoming when it was below freezing. "Extreme" anything wasn't invented yet. Not even a TV show.  Only recently have I discovered that what I was doing was impossible. 
To begin with, I wouldn't worry about the humidity. In another thread, the waterproofness of reloaded cartridges was discussed.  It seemed a consensus that a reloaded cartridge is pretty water proof so your humidity isn't going to change inside the cartridge. And too, your heat/air is gonna take care of most of the humidity.
 It has been proven that there are changes in velocity, pressure and POI when a cartridge is subjected to DRAMATIC changes in temperature.  So maybe some of this extreme powder may be called for.  I wouldn't worry about it too much but it may make you feel better.  If you're not motoring your rifle at the ragged edge of disaster, I wouldn't worry about it at all.  As Dave from WV said: "I've been killing deer for years with rounds that were not max. The poor things died readidly without knowing they'd been cheated." 

[Dave in WV]

beemanbeme  has made a good point about how temps affects a load's performance. You can have a max load that was tested at a cool temp with no problems and it may be an over pressure load if fired at a higher temp. Powders are affected differently by temp extremes. If you test your loads in the summer and use them in the colder months there should be no pressure problems. Your zero may change but you should not get an over pressure.

[AtlLaw]

<major snippage>Only recently have I discovered that what I was doing was impossible.  <snip>

I've had pretty much the same experience.   

It has been proven that there are changes in velocity, pressure and POI when a cartridge is subjected to DRAMATIC changes in temperature.

Again, I agree; the key word here being dramatic.  I have heard, but I can't give cites, this temperature thing is a result of when cartridges were loaded with Cordite, which was reportedly very temp. sensitive, and pressure tested in Europe then used in Africa.  If it ain't true it ought to be!

I do remember seeing, not too long ago, a chart, graph or something from a reputable source on the issue of the effects of temp. changes on velocity/pressure.  It confirmed my belief that changes within the temperature span that I normally hunt or shoot in are of little consequence to me.

So maybe some of this extreme powder may be called for.  I wouldn't worry about it too much but it may make you feel better.

Actually, I kinda think the "Extreme" thing may be a little of a marketing ploy based on people's belief in the subject at hand.  I now use them only because I have tried every possible combination of bullet/primer/case & seating depth with propellants marked IMR in the 18 calibers I load for and have now switched to the H's to do the same thing... 

However, in the pursuit of making a Bambi Banger shoot sub-caliber groups all this is real heady stuff and well worth untold hours of contemplation and discussion!   

[myronman3]

to me it does.  but in a different manner than others here are looking at.
      i look at the storage of my components.  primers and power are kept in an airtight container, with moisture absorbing material so that i dont have to worry about them.    that is the only way i worry about humidity.   at the moment i squeeze the trigger, i want all the confidence i can get.