This is the first that I have heard of IMR's or Dupont's 3031 ringing barrels in normal use!
3031 is a sentimental favorite of mine. I use it extensivly in the 358 Win with 180 gr bullets and 200 gr bullets. Also I used it for decades in my 6mm Remington International for 200 yard target shooting. My rifle is a 40X that was so chambered by Remington with a 1-10 twist barrel. I used that barrel for many years and it wore out from throat erosion even though the load was light. I loaded 30.8 grs of 3031 behind the 75 gr Sierra. That is a low pressure load with considerable space and no filler was used.
The use of that load was very important to me. I wanted to get and did get the high average award many times at both the Blue Trail Range's Big Bore League and at the similar league at the Bell City Rifle Club.
The Douglas barrel on the 40X is in excellent condition as was the worn out Remington barrel. In my experience 3031 does not ring barrels. I currently have it in 8 lb. containers.
The 6mm International cartridges 
