My 300 I just had a new barrel put on about 5 months ago. It was in the 40's then and this rifle would shoot a 2.5" group at 200 yds. In the summer time this rifle will shoot a 1" group at 100 yds but puts the bullets all over the place at 200 yds. I've heard that it must have a deep throat. Is there another reason?

I can't think of a reason why a gun that shoots 1" groups at 100 yds would "shoot all over the place" at 200 yds. Re winter verses summer shooting the difference in loads would be alot like adding .5-possibly as much as 1 grain between 40 degree weather and say the 80's.

Offhand there is only one reason I can see a gun really going bad at slightly longer distances and I just went through a situation like that. I had a scope with bad paralax. If I moved my head the scope crosshairs would move around the target. At 200 yds they would move about 3" and at 300 yds they would wander all over a 5" bullseye. Took me a while to figure that one out.....I used to shoot alot more and probably would have noticed it just wasn't right in my younger days.

You could be dealing with heat mirage, which is giving you bullet placement problems downrange. Try shooting as early in the day as possible and see if this doesn't help.

Based on your 100 yd. groups, I doubt that there's anything wrong with your rifle or ammo.......

AD

If your rifle has a wood stock I would suspect it is not bedded properly and the changes in the seasonal humidity is causing it to shift.

Thanks Guys. I will check my scope out even tho I just recently put this scope on Leupole 4x12.
The wood stock I think is OK this is the third barrel but thanks anyway. I will try shooting it when it is cooler.

sounds like powder being temp sensitive to me. Would it be RL22 by any chance?

Ask yourself.......how do you know the stock is ok? Did you remove the action and have it glass bedded? Did you check for out of place pressure points? Cracks? Is the barrel free floated?

I sealed that stock under the barrel and I redid the whole stock resealing it and yes it has a pressure point put in by the smith that put the new barrel on and test fired it at 100 yds in the winter time

JustC hit it. Temperature does affect powder. In the summer your barrel doesn't cool as quickly and the barrel temp WILL affect the shot.