How much does a hot barrel effect accuracy?

pabooger

I was sighting in my new 25-06 yesterday and after I had shot about ten rounds the barrel was getting pretty warm. My buddy told me that I might as well quit and let it cool down before I try to fine tune it any further. He claims that when the barrel expands from the heat it will rub against the stock in various spots and greatly effects the accuracy! What do you guys think???
BOOGER

kimberkid

Heat is one of a barrels worst enemys when you are talking accuracy, as the barrel heats up it will indeed expand and will rub against the stock in various spots, also with different amounts of pressure. You can generally tell when this is occuring as you hits will tend to walk in one direction or another, making a string of shots next to each other getting progressively further from your original POI (Point of Impact), if you let the barrel cool and your POI has returned to its origin, you know your barrel is indeed "bending" so to speak. Free floating the barrel will help reduce the problem, but even free floated barrels will tend to walk as they heat up ... the trick is to know how much to compensate for after X number of rounds

*edit*
My AR-15, which is pretty much tricked out with a free floated Stainless Bull barrel will start "walking" noticably at 200 yds after 40-50 rounds, it strings down and right almost an inch and at our annual varmint shoot, this will put you out of the running in a hurry if you don't compensate by aiming high and left to stay at your original POI ... this "knowledge" has allowed me to place in the top 3 spots for the last 4 years running ... last year was the first time I's sunk to 3rd. First and second place were taken by a father and son shooting the same rifle (a custom Tika bolt gun in 22PPC), I had to smile though ... the kid beat out his old man with a 50/50 with 8X's, Dad had 49/50 with 9X's ... I had 48/50 with 9X's

=================================
The only bad thing about choosing a Kimber ...
... there are so darn many models to choose from!
kimberkid@gunbroker.zzn.com

Edited by - kimberkid on 06/23/2002 10:13:36

Nighthawk

I think Kimberkid answered the question as well as could be answered.Your friend is right about the accuracy being affected by excessive heat.But you can take a five minute break and let your shoulder rest while your barrel is cooling.And it will be fine.What I wanted to emphasize is that when shooting a high powered rifle, about the time your rifle gets hot enough to affect accuracy.More than likely you are tire and not shooting your best groups either. So you need to take five as well as your barrel. There was an article in weapons and tactics for law enforcement magazine.Special edition by Patrick sweeney.

Good Shooting











Rugster

BoltactionMan

That heat is your barrels enemy on the inside as well as the outside. Throat erosion increases with the temperature of the barrel. Depending upon outside conditions, it may take well longer than 5-10 minutes for that barrel to cool down all the way.

KC

bwa

No doubt about it. My 30-06 will group OK for 5-7 rounds until the barrel is too hot to touch, then it begins to send them pretty far afield(the barrel is in rather poor condition also).

If it's OK with pabooger I'd like to ask the others if the same phenomenon occurs with handguns, which are typically designed for rapid fire. Will they also become inaccurate as the barrel heats up?

ericthered

I have an extremely accurate garand that is original GI. No
special or match parts.
It will hit 1" at 100 yds, but within 10 or 15 rounds it will
begin to drift. It can drift inches up and left.
Other rifles seem to take a bit longer to drift, but heat definitely
has a bad effect.
Eric

thats'me

coyote-man

pabooger,
When Iam checking a rifle for good load, I take with me a long stem thermonitor, which you can get a garden supply stores. I insert this into the barrel after I have fired a few rounds to see what the temp. is. This way I know when the temp. is back down close to normal so I can start another string.

ranahan

Talk about heat-walking barrels, I have an old thin side Browning Lever Rifle in .308. They have a very light weight 20" barrel. This gun is very accurate with good ammo & will put 2 shots almost in the same hole, 3 if they're not too quick. After that it will walk straight up the target 2 to 3 inches every shot (at 100yds.) for 2 five shot strings until it's printing a foot or more high. Then it will hold a 4 or 5" group there all day or until you run out of ammo. If I'm practicing rapid off hand fire in our normal 110 degree weather here, I just compensate (like sombody said) and I may cool it off with a nearby water hose. Some of you may blanch at that (!) but hot guns simply DON'T cool off in our summer weather. I wet down both me and the gun; run the hose right down the gullet and keep shooting.

ranahan