Shoulder bump on once fired brass???

Three firings will give you a very accurate measurement on your case for a headspace. I’ve adjusted now and found you can have a small variance from one case to another if you pre-measure each brass prior to sizing. There’s a click adjustable die lock ring now which seems to be the ticket to get all your brass squared away to an exacting figure. It’s very time consuming however, but perfection always requires much more work. Will you see it on paper? Well that really depends now on your barrel, powder lot, primer lot number etc. getting to your “hump” in the barrel which seems to equalize more MV and shaking your brass prior to chambering so powder levels out inside (fluffing the powder) can also assist in more consistent MV. There’s a lot to do in trying to get perfect numbers and one hole groups. I hope this helps a bit.

You’ll get a little variance potentially if you use too much lube as well. I personally usually fireform twice or three times till all the measurements are the same for a true fireform representation.