A while back I loaded some 40gr Nosler Ballistic Tips just to see if they'd work in my 1/7ROT Colt barrels. I had read that all sorts of bad things could happen-everything from bullets blowing apart in the barrel, to keyholing, to dogs and cats sleeping together.
I'm happy to report that nothing 'bad' happened at all. The accuracy was nothing to write home about, but that could very well have been caused by something on my end. Keep in mind that I didn't take any time to properly develop this load-I simply cranked up the Dillon 550B and slapped them together.
Disclaimer and corporate CYA: My "research" was not intended to be anything more than a quick and dirty test to see if 40gr projectiles would work in my own 1/7ROT barrels. Your results may vary. Different brands of bullet, a hotter powder charge, jacket construction, jacket thickness, or any number of other factors could yield results far different from what I observed. I am not a scientist, nor do I play one on TV. I did not utilize controlled, repeatable scientific testing protocols, nor do I claim that my testing is a definitive answer to the issue at hand. For all I know the next batch I loaded could have exploded, sending seismic shockwaves to all corners of the globe. These shockwaves could have broken off continent-sized chunks of the polar ice cap and caused the worlds oceans to rise-which could have wiped out human civilization as we know it.
In short, it's quite possible that 40gr bullets could wind up being more cataclysmic than the meteor that wiped out the dinosaurs
Use them at your own peril, my brother.