Load change maybe?

[Brux]

So I had 2 loads for my 308.
41.5/4064/175 SMK
43.1 Varget/175 SMK
These loads were shooting great with temps in the mid 70's or low 80's.
Now I tried both of them with temps in the upper 40's low 50's and groups have opened up, nothing else has changed.
Has anybody experienced this before?
Barrel is not copper fouled.

 

[Mattio]

the temp sensitivity of the powder could affect the powder performance. If you had a velocity for your loads at 70-80 degrees you could then compare your velocity at 40-50 degrees, then have a better idea what is going on.

 

[Deleted member 10043]

What was the accuracy before and after?

 

[DrewC]

That’s not much of a temp swing to really affect Varget. It’ll maybe drop velocity a few fps but it shouldn’t affect group sizes unless 43.1 is right on the edge of your node.

 

[Brux]

1/2 inch or better
today it shot a inch or a little more

 

[whatsupdoc]

Could it be you? sometimes we have good days and sometimes not so good.
I would retest it.

 

[Brux]

Second time I confirmed it.

 

[OLD308]

Not enough of a temp change for either powder. I’d check the usual suspects, scope mount, rings, scope, action screws, ect. Then check you dies, powder measure, ect. Use 4064 often, it’s not the powder. Can’t say about Varget, never was impressed with it. Also, is this from the same handload lot, or to different loading sessions.

 

[DrewC]

Chrono those loads next time and see if there’s been a change. Did you by chance use a different lot of powder?

 

[Deleted member 10043]

It could be ammo related just based on how it is stored. My .300 H&H is notorious for this. Don't be afraid to turn the box upside down and shake it a little the idea being you want the powder evenly disbursed in the case as much as possible for each case. I'm having a hard time trying to explain this phenomenon. It goes way back before the internet. People loading and shooting from the same location noticed a reduction in accuracy straight from the press to the rifle. Rolling the newly loaded cartridge along the table or bench improved accuracy. I've experienced even hangfire just because the cartridges were tightly stored bullet down in the box and from there straight to the rifle. Hope this makes sense.

 

[918v]

Your loads are crappy. The correct charges are 42.2/4064 and 43.5/Varget @ about 2.830” COAL.

 

[Deleted member 10043]

Christ in a side car.

 

[Brux]

Your loads are crappy. The correct charges are 42.2/4064 and 43.5/Varget @ about 2.830” COAL.

What is your reason for saying my loads are crappy?

 

[supercorndogs]

I would think it would be pretty tough to say not knowing what chamber you have, and nearly impossible not knowing what brass you are using. It does sound like you are on the edge of a node, if there is nothing wrong with the guns and shooting. You could try seating the bullets .01 or .005 deeper to break them loose, see if the bullets are corroded to the necks. It would be nice to know velocity. Are they about 2615? i have about the same thing going on with RL15 at 43.1g. I chrono and found 2615. I know when they shot well it was 2625. So i am going to up my charge to 43.4. In hornady match brass. In Laupua brass 42.4 of target gave 2620 with the 175 Nosler CC.

 

[918v]

What is your reason for saying my loads are crappy?

Because they failed to maintain accuracy through a weather change. Both powders are temp stable in your application.

 

[Deleted member 10043]

Don't listen to all this node bullshit.

 

[Brux]

I load as I go. I don't store ammo,but I will try to go up in charge and see what happens.