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How much does a warm barrel affect accuracy???
Cubslover
Member Posts: 18,601 ✭✭
I took the 243 to the range the other day.
I shot at 50yds first to check my windage. My first 3 rounds went through one ragged hole. I let it cool 6-7 minutes. Next three, same thing.
Pleased, I took it down to the 100 to check my elevation. First three in .7". Three more about 3 minutes later into 3"
Thinking I made the mistake. I let it cool another 5 minutes and put 3 more down range - .84"
Three more a couple minutes later in a 3.5" group. Does a warm barrel affect accuracy that much or should I try a different ammo?
Shooting a 100gr Sierra Spitzer @ 2960fps in a Federal factory load through a standard weight barrel. Air temperature about 60 degrees.
I probably should have taken one shot, waited 5 minutes, another shot, 5 minutes....... I just didn't have the time.
I shot at 50yds first to check my windage. My first 3 rounds went through one ragged hole. I let it cool 6-7 minutes. Next three, same thing.
Pleased, I took it down to the 100 to check my elevation. First three in .7". Three more about 3 minutes later into 3"
Thinking I made the mistake. I let it cool another 5 minutes and put 3 more down range - .84"
Three more a couple minutes later in a 3.5" group. Does a warm barrel affect accuracy that much or should I try a different ammo?
Shooting a 100gr Sierra Spitzer @ 2960fps in a Federal factory load through a standard weight barrel. Air temperature about 60 degrees.
I probably should have taken one shot, waited 5 minutes, another shot, 5 minutes....... I just didn't have the time.
Half of the lives they tell about me aren't true.
Comments
The reason is that game is usually taken with the first shot.
Of course, a sporter weight barrel will usually show the affects of heat before the varmint weight barrel will due to the greater amount of steel in the barrel.
RJSnow
Better barrels tend to show less effect of inherent stress in the steel when they get warm. A tightly bedded barrel may also react more adversely as it heats and free floating in some cases will help with this. If this is a hunting rifle, especially big game (deer, not prarie dogs) the advice to know where that first shot will go from a cold barrel is important. You might even save a separate target that you put up at the beginning of a shooting session, put one hole in, and take down until the next visit to the range. A 3 or 5 shot group made on 3 or 5 days, can be instructive.
Good luck.
It's just a coyote rifle, but I was just trying to dial some groups in.
It may be that the barrel when heating up is not expanding equally or when it is expanding is making contact with and getting pressure applied from the stock.
I have a Weatherby MkV Deluxe in 300WM and the first 3 shots at 100 yds can be covered by a dime. The fourth shot is always approx 3-4 inches off. After I let the barrel cool, I am back right on.
It may be that the barrel when heating up is not expanding equally or when it is expanding is making contact with and getting pressure applied from the stock.
+1
F.
I have a Weatherby MkV Deluxe in 300WM and the first 3 shots at 100 yds can be covered by a dime. The fourth shot is always approx 3-4 inches off. After I let the barrel cool, I am back right on.
It may be that the barrel when heating up is not expanding equally or when it is expanding is making contact with and getting pressure applied from the stock.
Again, it's a free floated barrel. Plenty of room for barrel expansion. I'm thinking of getting a heavy barrel installed on it as it's varmint rifle.
This is going to be atypically short...
Barrels that are made quickly without the benefit of stress relieving heat treatment, contain stresses in the steel when they leave the factory. When you heat the barrel up by firing your loads, the heat from those loads cause those contained stresses to unload. Then when you allow the barrel to cool, the barrel goes back to its original condition.
As v35 states, you could have the barrel cryogenically treated or as you state, have the barrel replaced. Either way, what you need to pay attention to is who makes the barrel and what techniques do they employ while making their barrels. You need to buy a barrel that is stress relieved during the manufacturing process.
There's some more but I'm really pushed for time. Do some searching on barrel making and barrel makers, looking specifically at stress relief.
Best.
When you stress a section of steel, you make it less dense. Thus,..when it heats up,..it is less strong,..and therefore the surrounding steel will be affected differntety that the non-stressed portion of barrel, and that area will react to heat more readily than unstressed steel. If you recall from science class,..heat speeds up the molecules,..and thus changes the strength factor of the steel. NOW, when you heat it up,..the harmonics will NOT be the same as they are on cooler steel. That is the reason why your cold barrel holds tight groups andd your hot barrel throws shots.
You also need to check your barrel contact with the stock when hot vs cold. If it warps over and touches the stock when hot,..releiving that area of material will help greatly with that. 3.5" at 100yds indicates an issue,..I would bet stock contact on a warm barrel or a horrible factory barrel. Try running 10rnds,..and record at which shot it goes bad.
Cryogenic treatment removes the internal stresses.