Load Adjustment?

[Lonewolf74]

So if you developed a load in cold weather and as it gets warmer out your velocity increases and seams to take you out of the node, or vice versa going from warm to cold weather.

So I believe all I need to do is reduce the charge and get back into the node I had and perhaps fine tune more than what it was.

So anyway my question, is there any calculation or something to figure out about how much you would need to increase or decrease the charge weight to hit a certain velocity? So for example if I needed to reduce the velocity by 30 fps how much do I reduce the load, or is it more of a guessing game and testing a reduced load or 2?

 

[dok7mm]

If you shoot over a chronograph, you should have made notes on the velocities and temperatures you had with your powder. You can figure you velocity change per degree and come pretty close, to change your charge weight for different scenarios.

Or work your charge/ temp by reshooting.

 

[Greyfox]

When planning on using my rifle across a wide range of temperature, I use one of the temperature controlled powders like the Hogdon Extreme. Temperature effects used to be much more of an issue before the introduction of these powders and I have rarely, if ever experienced temperature extremes taking me out of the accuracy node using these powders when a proper ladder test was performed during load development. I would also avoid developing a load that was close to the pressure max in cold weather to provide a margin of safety. Once your load is developed, you can test the velocity of your load at the extremes of the temperature range you will use the load, and if neccessary, compensate for any change in velocity with your ballistic calculator without having to re-work your load. IMO.

 

[Lonewolf74]

I am going to test more powders to try and find a more stable powder that still gives me the velocity I'm looking for.

The issue I have right now is i did a quick load work up because it was a new lot of RL26 and was noticeably faster burning than the first lot I had. I did this load work around Christmas and it was cold around 1-2 degrees f. It seemed very dialed in though .75" at 300 yrds and avg velocity of 2960 with ES of 4 (over 5 shots).

Now yesterdays with it 40 degrees out it had an avg velocity of 2995 with an ES of 40 and 2" group at 300.

Group size could of been more me and dealing with some mirage but the ES went to crap. So either the load wasn't as dialed as I thought or the powder is that sensitive.

 

[Mcarso1]

What does ES stand for?

 

[lancetkenyon]

Extreme Spread.

Difference in low to high velocities.

SD is Standard Deviation. Difference from average speed. A huge formula to figure out.

I have not noticed a huge difference in speed using RL26 from 95 to 10 degrees. How new was your barrel when you started? Barrels "break in" and speed up after 50-120 or so rounds from new.

 

[Mcarso1]

Thanks , newbie questions. Appreciate the knowledge

 

[Lonewolf74]

If you shoot over a chronograph, you should have made notes on the velocities and temperatures you had with your powder. You can figure you velocity change per degree and come pretty close, to change your charge weight for different scenarios.

Or work your charge/ temp by reshooting.

The only notes I have for this lot of powder is from the couple days I did a load work up in cold weather.

I could use it as reference for about how much I need to reduce charge to reduce velocity by a certain amount, I would think anyway?

I do need and want to shoot more in different temps and conditions to see how it effects my loads. With more data I could figure out fps/deg and such.