A few months ago I posted about how I thought my Chrony was messed up. I took my CZ 550 American in 7x57mm Mauser with me on a visit to my little brother in El Paso, and we went to his shooting range for a session. I was shooting handloads (162 grain Hornady with 48.2 grains of H414 in Remington cases and Federal primers) and was getting an average of 2,845 fps. I came back home to Grants, N.M., went to Bonita Canyon where I do a lot of shooting, and the same load averaged 2,815 fps. The difference, I thought, was that the sun was going right to left in El Paso and from top to bottom in Bonita Canyon. With the SSTs I was shooting sub-half minute groups in El Paso, but the groups opened slightly in Bonita. Last Saturday I went out with a shooting friend to some BLM lands to do some more load testing, where I kept the same distance to lands setting, but increased the load in .3 grain increments. Well, for three shots that 48.3 grain load dropped the velocity to 2,755 fps. I got to thinking about all the variables and why the same load kept dropping in velocity and as I thought I had to hike my jacket around my neck more because of the cold. It hit me then ... in El Paso it was 105 degrees, in Bonita Canyon it was 80 degrees or there abouts, and it was about 45 or 40 degrees when I went last Saturday. On Monday I called Hodgdon's to ask about temperature change affects on H414 and the technician said there is definately a change when you see drops of 20 degrees or more. All this time it has not been my Chrony, it has been the darn temperature. The tech said none of the ball or flake powders are the Hornady Extreme powders, so there will be variations. This gives rise to a question. If I know at what velocity gives the ultimate accuracy in my rifle, and I have a fair idea what the temperatures will be like in the areas I plan to hunt, do I adjust the powder charge accordingly to get the same velocity at a given temperature? Just food for thought! Tom Purdom

Interesting story Thomas, thank you.

A lot of benchrest competitors load at the range for that very reason - they can vary their load up or down depending on temperature and conditions of the match.

Bill

I imagine sitting in front of a pile of cartridges left over from the trips in different temperature zones (to which the charge has been adapted).
Mostly confusing.
It will be easiere to find out by how many clicks on the scope changes in ambient temperature are corrected, instead of changing your favorate load.

Develop your load as I suggest on my webpage (bottom of this post) and you'll find that the velocities won't be as erratic in temperature swings.

Dan

Green788, I enjoyed your website. It was very informative. Thanks.