Speaking of hammer and nipples, the contact between hammer face and nipple should really be paid some attention. A good fit will prevent uneven peening of the nipple, promote longer nipple life, and more concentrated flame down INSIDE the nipple.
Prussian Blue on the nipple face and touch the hammer to it, and the high spot shows inside the hammer cup. Take you dremel with a flat endcutting burr, and carefully grind off the blue. Touch hammer to nipple again, grind and repeat until you have 100% contact.