257 Wby Heat Cracks

[Twud]

Had my smith take a look at my 257 Weatherby with his bore scope. He found "heat cracks" around the end of the throat. I took a look and there were tiny slits on either side of the throat consuming about 90 degrees per side. They had copper really stacked up in them. Smith says no danger but degraded accuracy. Cause- too hot a load with too light a bullet. I shoot 100 Grain Nosler Partitions over 64 grains of H4350. A warm load, but I wouldn't call it hot.
New Hart stainless barrel turned to match Weatherby's contour, $550. this is a Mark V jap gun. With all of Weatherby's hype about velocity, do you think there's a chance in hell of them getting behind this?
I have never heated this gun up. Only shoot 3 shot groups, and wait for the barrel to cool before continuing. Only time I ever went beyond 3 shots in a row was when I was culling deer for the state. Looking back, I think I've reloaded my original 60 cases maybe 4 times, so it hasn't seen a lot of use. Never had a loading or extraction problem, and my brass looks great.
What to do?

 

[Rustystud]

Twud:

Heat cracking is the norm in a center fire rifles barrel life. The hotter and higher presure loads you shoot the faster the heat cracking and shorter the barrel life. This becomes a major problem when pieces of the bore break away and the bore becomes rough and uneven. It usually starts in the throat area and works it's way forward foe several inches. Whole sections of rifling can and will break out.

Rustystud

 

[M700]

How's the accuracy?

It's normal for a barrel to start showing those small cracks in the throat area. Even my mild shooting .308 target barrels eventually develop quite a spiderweb of 'em. As long as it's shooting fine, you're likely okay. Someday it will be time for a new barrel.

FWIW, Guy