I guess this is kind of a newbie question, but how do you know when a barrel has sufficiently cooled between strings? I worked up a load for my .308 this past spring, and I thought I was allowing the barrel to cool between each string by just feeling it with my hand and guessing when it was more or less at the ambient air temp. When I took the same rifle out before hunting season to make sure everything was still good, the POI of the first two shots was consitently 4" higher than the POI of the next two. If I fired another string while the barrel was warm (not hot to the touch, but warm) I got a consistent group of about 1". Any thoughts?
When is a barrel cool?
- Thread starter Chinook78
- Start date
A barrel is always sufficiently cool. Know where it impacts on a cold bore as that will be your hunting shot, then shoot it until you are sore. A good rifle will still shoot inside of most of us positionally when hot.
A ~4 MOA(assuming 100m) POI change tells me there is a different problem than heat. Something is loose, or the barrel is touching etc.
What kind of rifle?
A ~4 MOA(assuming 100m) POI change tells me there is a different problem than heat. Something is loose, or the barrel is touching etc.
What kind of rifle?
If you cleaned the bore after your last outing, the first two shots might simply be the "unfouled" bore POI. For hunting, either do not clean the bore after you have zeroed it (my preference), or fire one or two fouling shots.
As for "too hot" while shooting - it's subjective. I try to keep it so that I can grasp the barrel at the receiver and hold it without discomfort. This can extend barrel life.
As for "too hot" while shooting - it's subjective. I try to keep it so that I can grasp the barrel at the receiver and hold it without discomfort. This can extend barrel life.
Bedding issue if the groups are not opening up. Is the barrel free floated ? Is there a pressure point that is affected by temp changes ? Is it a thin barrel or a heavy profile one ?
If you are hunting with it sight in with cold barrel shots as that is how you will shoot hunting. However, a 4" change of POI between a cold and slightly warm barrel is a bit much. I have a 300 weatherby with a rather thin barrel that will change POI after 3-4 shots but not by that much.
Check bedding and screws.
Another posible reason ( not sure if it will apply ) but I've had scopes change POI if I shot at different magnifications. It was an issue that had to be fixed but it drove me crazy unitl I checked with a bore sighter to see if it shifted when I changed magnification
If you are hunting with it sight in with cold barrel shots as that is how you will shoot hunting. However, a 4" change of POI between a cold and slightly warm barrel is a bit much. I have a 300 weatherby with a rather thin barrel that will change POI after 3-4 shots but not by that much.
Check bedding and screws.
Another posible reason ( not sure if it will apply ) but I've had scopes change POI if I shot at different magnifications. It was an issue that had to be fixed but it drove me crazy unitl I checked with a bore sighter to see if it shifted when I changed magnification
If you spit on it and it sizzles, it's not cool.
There is a difference between warm, hot and cool.
Cool would be when you first take it out of the locker.
Shoot your rifle enough at the range and you will get to know
your target groups and where your barrel gets too hot to
group nicely.
Some barrels are more particular to heat than others.
To cool a barrel, it helps to keep the bolt open and lean the rifle in the
rack barrel up. This creates a stove pipe effect helping the barrel to cool
somewhat faster.
There is a difference between warm, hot and cool.
Cool would be when you first take it out of the locker.
Shoot your rifle enough at the range and you will get to know
your target groups and where your barrel gets too hot to
group nicely.
Some barrels are more particular to heat than others.
To cool a barrel, it helps to keep the bolt open and lean the rifle in the
rack barrel up. This creates a stove pipe effect helping the barrel to cool
somewhat faster.
At least you get 2 shots before it shifts; a barrel that shifts drastically after the first shot is enough the make a patient man yell at the wife or kick the dog even if he has neither.
The simplest fix is unscrew the barrel and throw it as far as you can.
The simplest fix is unscrew the barrel and throw it as far as you can.
If your bedding screws were loose, your groups would be huge. ie, would not put POI high then low then shoot a consitant 1" group after that.
My bet is either a clean cold bore or oily bore. As mentioned above your barrel shoots better fouled. After sighting it in don't clean it until after the hunting season. If it gets wet it is ok to to run a loose fitting patch down the barrel to dry it.
My bet is either a clean cold bore or oily bore. As mentioned above your barrel shoots better fouled. After sighting it in don't clean it until after the hunting season. If it gets wet it is ok to to run a loose fitting patch down the barrel to dry it.
Really sounds to me like you are just getting a difference in fouling in the barrel.
Clean your gun, fire a few shots to foul it again, then leave it be until after the hunt.
Also, check your crown for burrs - an outside chance it's doing it, but unlikely I think.
As for barrel temps ... I shoot my rifles until they are Coffee hot ... can hold it, but don't want to hold it Hot. As long as I can touch the barrel without acually burning myself, it's cool enough to shoot.
You didn't mention something else that might be a cause ... Synthetic Stock? Possibly it's touching where it shoudln't and as the temps increase, it's softening and changing the amoutn of pressure ont eh barrel - that would explain the difference after your first few shots as well.
Clean your gun, fire a few shots to foul it again, then leave it be until after the hunt.
Also, check your crown for burrs - an outside chance it's doing it, but unlikely I think.
As for barrel temps ... I shoot my rifles until they are Coffee hot ... can hold it, but don't want to hold it Hot. As long as I can touch the barrel without acually burning myself, it's cool enough to shoot.
You didn't mention something else that might be a cause ... Synthetic Stock? Possibly it's touching where it shoudln't and as the temps increase, it's softening and changing the amoutn of pressure ont eh barrel - that would explain the difference after your first few shots as well.
Thanks for the feedback! The rifle in question is a post '64 Winchester M100. I didn't clean the barrel between when I was testing in the spring and in the fall. I did strip and refinish the walnut stock immediately after I bought the rifle, but there couldn't be more than a few thousandths difference either way between the old finish and the new... ?
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Many off the shelf rifles, have some upward pressure applied at a pad on the for end.
Unless a rifle, is glass bedded, this is a good way to go, to keep groups consistent.
As mentioned previously, each rifle is a beast unto itself. I have a few that will shoot tight groups when it's +45C in the shade and at -40C in the winter. The only difference between the groups will be elevation.
I have a lovely old world Mauser that changes with the weather. The only way I could get that rifle to settle down, was to put it into a laminated stock and glass bed it. I refuse to do that to the original stock.
Try a bit of upward pressure on the barrel, about 4cm from the fore end tip. Not on the sling swivel.
The best way to do this is to hang a weight of about 5lbs from the tip of the barrel and slide in a shim that is just snug. Make sure the action screws are torqued properly before doing this.
This brings up another subject. Torquing the action screws. It used to be pretty common to use a torque wrench to set the action screws. With the advent of synthetic and aluminum bedding, it really isn't needed. Even some of the laminated stocks, especially when they're bedded, don't seem to require it.
The list goes on and on.
I have a Ruger No1, in 338-06, that shoots the first shot 1in low at 100yds and everything else groups tightly 1in above it.
I've done everything imaginable to that rifle, other than taking off the barrel and setting it back one thread and rechambering it, then screwing it back on with more torque.
I've heard this works. I don't know, it's another project waiting patiently in the wings for its turn.
Unless a rifle, is glass bedded, this is a good way to go, to keep groups consistent.
As mentioned previously, each rifle is a beast unto itself. I have a few that will shoot tight groups when it's +45C in the shade and at -40C in the winter. The only difference between the groups will be elevation.
I have a lovely old world Mauser that changes with the weather. The only way I could get that rifle to settle down, was to put it into a laminated stock and glass bed it. I refuse to do that to the original stock.
Try a bit of upward pressure on the barrel, about 4cm from the fore end tip. Not on the sling swivel.
The best way to do this is to hang a weight of about 5lbs from the tip of the barrel and slide in a shim that is just snug. Make sure the action screws are torqued properly before doing this.
This brings up another subject. Torquing the action screws. It used to be pretty common to use a torque wrench to set the action screws. With the advent of synthetic and aluminum bedding, it really isn't needed. Even some of the laminated stocks, especially when they're bedded, don't seem to require it.
The list goes on and on.
I have a Ruger No1, in 338-06, that shoots the first shot 1in low at 100yds and everything else groups tightly 1in above it.
I've done everything imaginable to that rifle, other than taking off the barrel and setting it back one thread and rechambering it, then screwing it back on with more torque.
I've heard this works. I don't know, it's another project waiting patiently in the wings for its turn.
