Once the plastic has been cooked for the tails and bodies I shoot anywhere from 350 to 320 degrees. Most of my baits are smaller but I do make a bunch of 4" plus baits for waldos and inject the body plastics between those two numbers and haven't had any come apart. I've had tails bitten off, leaving a stub of color or taing the who tail and some of the body color but I don't have issues with separation at the weld.
Little piece of advice though if you're shooting a ton of a color for tails and cut them off to store in a bag for later use, cut the tails longer than you want on the bait because the tails will get oily in the bags and if you don't offer a fresh cut or wash the tail sections in a good alcohol wash that oil will not allow a good weld. I make a couple thousand of the 1 1/2" Thump-Its at a time and just cut the baits in half for the tails. When I want to use some I take the time to cut them back to the size I like....about three body segments from the tail stem.