when i site my rifle in i always fire 3-5 shots and wait till barrel cools down.. question is how big of a difference hot barrel realy makes when it comes to grouping??

This is not a concern to me as I don't shoot in any rifle competitions. From my hunting stand point of view, my first shot is always from a cold barrel. So when I sight the rifle when getting ready for the hunt, it's a cold barrel. I limit a cold barrel sighting session to 5 rounds. Won't do anymore til it's cold again.

To be honest, I sight all my rifles in at 200 yards. My target is 6 inches in diameter, and as long as all my shots fall into that circle I'm set for hunting. I've shot anywhere from 20 to 100 rounds through any given rifle going from cold to hot barrels & stayed well within that 6 inch circle on all my scoped guns. My Bushmaster .223 I can shoot all day with hundreds of rounds at that distance & all shots remain within that circle.

I don't know what you want for accuracy, but, this is what I expect for all my store bought guns, I have no custom rifles.
Keep it coming...

As barrels heat up from rapid firing, dimensions change. Those that chronograph are familiar with velocity increases as the barrel becomes hotter, although such increases in a practical sense are only academic.

More important is that the bedding of the rifle is solid and that the barrel has no contact with the stock. Barrel and receiver heating can cause shots to change POI as the pressure against the forearm changes. In some cases it can be significant.

And, that is what a prepared hunter or varminter will do -- fire a number of shots in rapid succession and see if there are POI changes. If significant, then bedding and free floating are some measures that can minimize impact shifts.

some rifles actually shoot better when they are hot.

i have one enfield which shoots 1 inch groups cold but as you shoot will tighten up to a half inch and as the barrel gets hotter and hotter opens back up to about a inch and a half.

for any kind of hunting this really has no effect.

Spacedone wrote:

some rifles actually shoot better when they are hot. i have one enfield which shoots 1 inch groups cold but as you shoot will tighten up to a half inch and as the barrel gets hotter and hotter opens back up to about a inch and a half. for any kind of hunting this really has no effect.

I have a Browning A-Bolt in which accuracy deteriorates rapidly as the barrel heats up. Three shots and then it has to cool down or the grouping suffers.

yzchamp wrote:

when i site my rifle in i always fire 3-5 shots and wait till barrel cools down.. question is how big of a difference hot barrel realy makes when it comes to grouping??

You will have to determine the effect for your particular rifle because the it varies greatly from rifle to rifle, even in multiple samples of the same rifle the difference can be great.

Among the rifles I have, some change POI drastically as the barrel heats, some show no change even when the barrel goes from cold to too hot to touch.

Most of my shooting is at a rifle range, and I find the barrel gets to the point of needing to cool down after 3 shots (4 with a stainless heavy barrel). Beyond that your group will doubtlessly open up. I feel the barrel about an inch or two from the back. If I can't comfortably grip the barrel there, then it's too hot to shot so I have a cigarette, drink a coke or have a whiz; anythig but let that barrel cool. Not only will your accuracy go all to hell but the barrel also if you do it too often. Just one guys opinion. Best wishes.

Cal - Motreal