marginal stability

[rammac]

ok I have loaded ammo at 200'and at 5000 they shoot high about 2" at 100 m and the handloads are very hot up here... you need to drop your powder charges 1.5 grains so you will not have flattened primers.. from 200 to 6000 elevation.. I am sure that is why the 416 rigby is loaded at 40 000 cup instead of 50 000 cups because in africa it is high elevation.. I think that elevation has more effect than tempature.. another thing if it is light rain you velocity will go up as much as 75 fps..

In my opinion you are incorrectly assuming that the higher impacts are are due to the load being hotter when in fact it's probably due to higher BC values that are creating a flatter trajectory.

Temperature has a greater impact on trajectory. Higher altitudes usually result in lower temperatures. Higher altitudes will also cause the pressure to drop.

All of those changes at higher altitudes will produce higher BC values.

 

[lancetkenyon]

If you are getting a 2" variation at 100m zero, you have another issue than elevation change. If you are shooting in low elevation, low temps, then go up to high elevations/higher temps, that is more likely where you are getting your velocity increases. Powder temp sensitivity, not elevation/density altitude issues. Although, I have heard of some powders gaining pressure at extreme low temps too.

Every single rifle I have, I sight in and zero @ 1100' AMSL, and hunt anywhere from 1000-8000'. My 200 yard zero never changes at any altitude differences. Actually, they don't even change zero at temp changes, from 20 to 110+ more than 1/4" @ 200. But I try and use very temp stable powders for that reason.

I did have a .25-06AI that loved RL22, but temps had to be watched carefully. RL22 swings about 2fps per 1 degree of temp changes. Zero always stayed the same, but drops at distance would vary due to velocity changes, and DA changes of course.

 

[DMP25-06]

22" 6.5 SLR pushing a 130 OTM @ 2901fps, 454 yards.
View attachment 196065

Lancetkenyon ,

FANTASTIC MULE DEER !!!
Congratulations to your daughter !!!!
You must be SO PROUD of her .
And , a great picture , by the way .
What state ?

DMP25-06

 

[lancetkenyon]

Lancetkenyon ,

FANTASTIC MULE DEER !!!
Congratulations to your daughter !!!!
You must be SO PROUD of her .
And , a great picture , by the way .
What state ?

DMP25-06

AZ, public land, general hunt. VERY proud....and jealous too. She smoked a good pronghorn too last year.

Back to the topic. I would rather have a bullet fully stable at any elevation, than marginal at some, and fully stable at others.

 

[Coldfinger]

its a 6 creedmore twist rate measures 7.75 trying the 115 berger. Im thinking to switch to the 108EOL and call it a day.

The plan would be to use this for antelope in new mexico a good ways from New England. I will have another proven at elevation gun with me.

I live at 1500 feet or so in Western New York, I've never seen much shift in impact going out to 10000 ft in Colorado or 8000 in NM. Impact seems to elevate a couple inches at 100 yards so I just rezero when out there. If I have max loads when I go hunting they seem to cross the line at elevation for some reason, sticky bolt, flattening primer bevels. I'd back them down a bit going forward.