Angus1895, I use a 32 TPI hack saw, but the Trick is how I hold them. I drill and ream a piece of steel at just over bullet diameter. As an example for the 8MM bullet I make a hole of .325" in the steel. It has to hold about 2/3 of the bullet. I then split the side of the steel with the saw so if I clamp it in a vice it collapses and gets smaller.
So, I insert the bullet to about 2/3 deep in the hole and then clamp the steel in my vice. That holds the bullet tight and I slit the bullet down to the steel. I release the bullet and turn it so the other side it up, and I can see the saw slot. I saw again from the other direction to that slot. Drag the bullet across a file to clean off the saw tooth marks and you can see the thickness of both core and jacket.
I have sectioned a lot of bullets including the FTX made for the 30-30 (140 grain) The FTX and the GMX are made very similarly but the FTX cavity is wider for the somewhat lower velocities it's made to expand at. I loaded some of those in my 300 savage M99. My idea was to have better expansion at longer range for antelope hunting. I shoot a 150 grain Remington Core-Lokt zeroed at 200 yards and that is just fine for any deer of antelope, but I started to wonder how the lighter and more aerodynamic 140 gr wold do. I am going to shoot some at paper soon. The savage shoots a lot better then it should with the 150s, so I don't think I'll change, but if the 140 FTX do as well they may be a bit better bullet to use on elk because they will retain 95% of more of their weight, where the 150s I use usually loos about 1/3. Testing is not done yet.
