Range Report Altitude effects on a 7wsm load.

[Trevor300wsm]

Can someone point me in the right direction on where I can find some info on altitude effects on loads please. I just bought a 7WSM and the previous owner had a nice load developed for it already, but he shoots at ~6,000 feet ASL and I live at ~890 feet ASL. The load is a "max load" for the rifle at 63gr of RL-22 at the 6,000ft elevation. Where is some info discussing altitude effects on loads? Any help would be appreciated.

Thanks,

 

[bohem]

Re: Altitude effects on a 7wsm load.

http://www.jbmballistics.com/ballistics/calculators/calculators.shtml

 

[Trevor300wsm]

Re: Altitude effects on a 7wsm load.

Bohem, thank you for the link.

However, my question is really more along the lines of safety. I understand trajectory/altitude relationships. What I am not sure of are the factors with the different pressures (max pressures) at given altitudes since this is a max load.

 

[bohem]

Re: Altitude effects on a 7wsm load.

Gotcha.

It won't matter; temperature changes are a bigger concern. RL-22 is pretty temp sensitive.

 

[Trevor300wsm]

Re: Altitude effects on a 7wsm load.

Bohem, thanks for the info. Yeah, the PO said that the load was very temp sensitive and was developed during the winter and was close to max, then when shooting during the summer in 90* plus weather, it was showing signs of over pressure.

 

[Skyking]

Re: Altitude effects on a 7wsm load.

The change in elevation won't have an effect, but like the other guys said, temp will.

Try using 64-66g of h1000 with 180 Bergers touching- jammed 10 tho over CCI-BR2 primers. That load shoots good in any of the 7 different 7wsm's that I reload for. And with h1000 you won't have the temp issue.

 

[cypriss32]

Re: Altitude effects on a 7wsm load.

I used to shoot 62.0 Grs 4831scc with win brass, 180gr VLDS, 2.935 win primers.