Seems I remember when TSX first came out there was problems with fouling in barrels. Think I read that it was fixed by putting a couple groves in the bullet. How that stopped it I have no idea but that was the claim. Something about Barnes bullet's, even the old cup and core bullet's had jacket's made of pretty close to pure copper, jacket's were copper tubing. Everybody else's bullet's were made of stuff called gilding metal, no clue what that means. But even gilding metal leaves copper fouling in barrels to some degree and sounded like pure copper even more. I know that you clean all the copper fouling out of a barrel, you have to fire a couple fouling shots to get the gun shooting right again! I think that the mono bullet's will do no more damage to the Mod 70 barrel than any other bullet. What might cause a problem is not cleaning the barrel at all. I recall an article Steve Timm did in Varmint Hunter Magazine years ago. He'd got a rifle from a friend and it didn't shoot real well but still wasn't bad. Well he decided to clean it and seems he spent almost a whole day getting out the copper fouling. After that the rifle shot very well! I would think that fouling caused by mono bullet's would only be a problem if you didn't keep most the fouling out to begin with. I'm guessing that the copper in TSX bullet's may be softer than in gilding metal bullet's and could foul faster. But can't see how that could ruin the barrel. Clean it well after use! Or if you don't like that idea, don't shoot mono bullet's in it, stick to cup and core. Either way now and then the copper fouling will need cleaned out!
