Nobody explained why to the the dear boy. I am not an expert by any means nor am I a metalurgist but let me try to explain this to you. Steel expands at a rate of .000007" per degree F. Therefore, if you have a 1" diameter barrel which is nominal at 68*. At 100* that barrel would be (100-68)x.000007" or 1.00022". Now this is outside diameter which, although very small, will increase pressure at any contact points along the stock which will change the harmonics of the barrel. Now add this same expansion rate to the bore will cause the bore to become smaller in diameter which also changes the amount of friction on the bullet as it travels down the barrel.
Then you have to add the increased temperature from continued firing and there you have it - a change in accuracy and or point of impact.
But don't let that stop you from shooting in the summer. Practice, practice, practice makes you a better shot.

Thanks Bronko,

I knew there was an explanation. When it gets scorching I'll sit it out but for now I will mess around. It's not like I'm going to site a gun in now and not shoot until deer season.

All of that may be true Bronko. But it shouldn't make much of a difference in the long run because targets expand also and the bull is bigger.

LMAO Semi. I should have known you would come back with something humorous. I guess I deserve it for all the times I take a crack at you.

It gets hot here in the summer. i just take 2 rifles as some others here seem to do. i leave very early in the morning and don't seem to have a problem with the heat.shorter earlier shooting sessions with more frequency, seem to be the answer for myself in the summer months.in fact the lil lady and i have a outing planned for the morning. we will be out shooting by 6:00 or 6:30 in the am.. Ray

semi, what I do to keep the heat off me in the summer is have the wife put here HOOTERS t-shirt on and stand close to me and provide me with shade. HEAT not the type that ignites and burns down shanties but the type that excites and brings down panties. sqezer 6-11-11

Pictures would help

I don't like shooting in the heat, but I still do sometimes. I bring 2 rifles and alternate shooting, taking breaks. It is still good practice and fun, but I've found that I usually need to have an extended range session in the fall when the weather is cooler to do my final sight in. Sometimes the POI changes, sometimes a load that shot well in the summer doesn't do as well with cooler weather and vice versa. If it's 90 degrees of less, I will consider going out and shooting. Over 90, forget about it...

I walk down and draw a circle around the shot I just took.

Keeps me from getting bored, and taking the next shot too fast.

I walked over a mile on my last shooting session.

To heck with walking back and forth to the target LOL. I take my rifle over under the shade of a tree and let it cool down. Along with myself.