Does the weather really affect your loaded ammo ???

[Jono Joseph]

I found when we shoot in much warmer weather 30' c up i find the recoil on my .470Nitro Express is bumped up as compared with normal ( south african ) hunting conditions 22-25'c.
Have you seen this too also the rounds start to become a bit more "sticky" in the chamber they do not just fall out?

Shot Shot

 

[DOC-404]

Jono, air temperature, altitude and humidity will always affect both ammunition and shooter. This is more evident with hand-loads than factory ammo. I always use factory ammo on DG and I always try to keep my ammo as cool as possible under the circumstances.

Here is a good article: http://www.longrangebpcr.com/Accuracy.htm

 

[lcq]

The powder type makes the most difference. Some powders are extremely temperature sensitive IMR and RL come to mind, others like Hodgdon Extreme series aren't.

 

[BRICKBURN]

Jono, come and hunt some Canada Geese with me in December.
It works the other way just the same.
The first shell is kept warm in your hand until just before you are going to shoot. Otherwise on really cold days you may not get enough power to cycle your automatic.

I have also seen altitude matter. More after the discharge than inside the barrel.
If I am going into that thicker air by the coast I make sure to check my rifle again.

Doc has some good advice.

 

[IdaRam]

Back when I used to have time for such things I used to really enjoy shooting LRTR (long range tactical rifle) competition. One match afternoon was 105 F plus. That's when I discovered that Hornady 6mm 105 gr A-Max's start to come apart in flight at about 3100 fps out of a 1 in 8 twist barrel. I was shooting Hodgdon H414 powder which produced great accuracy and velocity, but I ended up switching to H4350x to reduce the sensitivity to temperature exhibited by 414. The hot temp of that day increased pressure to the point that the bolt was hard to open and primers were cratered and really flat. It just so happened that I was pushing the bullets close enough to their max that the increase in velocity was more than the lightly jacketed A-Max could take.
So, for sure, temperature with some (most) powders will definitely increase pressure and velocity. And in your case, felt recoil. Like you need more recoil with a 470 NE

 

[PHOENIX PHIL]

Yep, no doubt about it. Have proved it to myself on the hot end way too many times. Like IdaRam, I've seen the pressures increase to the point of sticky bolts with IMR4350. Have had extremely accurate RL15 loads at 60 degress go all to heck at 80 degrees.

The Hodgdon Extreme powders I've also found to be far less sensitive to temperature.

 

[Jono Joseph]

Okay i knew it would affect it but the effect in the 470ne is marginal at this point i found it on a 223rem mag even greater i went from 22'c to 33'c i saw the speed hop change its mind totally.
It went from 2800fps to 3100 which was quite a jump i though.
that was with Somchem s335 crazey what you learn when you put effort in.

We have a lot of clients that just say wow it felt like my rifle kicked a bit more today...
Great to know.
Is there some kind of app that would (kinda) give you the speed change as the temp changed.
Hold on thats in development now ....

Shot Shot

 

[Jono Joseph]

Jono, air temperature, altitude and humidity will always affect both ammunition and shooter. This is more evident with hand-loads than factory ammo. I always use factory ammo on DG and I always try to keep my ammo as cool as possible under the circumstances.

Here is a good article: http://www.longrangebpcr.com/Accuracy.htm

Thanks for your advise its always good to hear what the other hunters out there do.....
Suppose it would be situation specific...

Shot Shot

 

[lcq]

Okay i knew it would affect it but the effect in the 470ne is marginal at this point i found it on a 223rem mag even greater i went from 22'c to 33'c i saw the speed hop change its mind totally.
It went from 2800fps to 3100 which was quite a jump i though.
that was with Somchem s335 crazey what you learn when you put effort in.

We have a lot of clients that just say wow it felt like my rifle kicked a bit more today...
Great to know.
Is there some kind of app that would (kinda) give you the speed change as the temp changed.
Hold on thats in development now ....

Shot Shot

My advice is to play safe and either develop your loads when it is hot or deliberately run them well below max. The possibility of an explosion next to my head really scares me into being very cautious.

 

[tarbe]

Yup, thermodynamics at work.

I have had people look at me funny when I told them I refuse to work up my hunting loads in temps that are 30-40 degrees different from expected hunting temps.

One of the few useful things I learned in school!

 

[Nyati]

I´ve seen a Glock blow up using a hot 9mm load with Vihtavuori powder (from Finland), in an IPSC Match during a hot summer, close to 40ºC.
I also see our serious trap and skeet competitors keep their shells in coolboxes during the summer.
So yes, ambient temperature does affect ammo, some powders more than others.

 

[JTEX]

The .223 is a considerably higher pressure round than the .470 to begin with it would show up more.

 

[Jono Joseph]

Thank you for all the info.
I think i have my mind made up...

Shot Shot