Some time ago, I started buying a VLD seater stem with every Type S Redding setup I have (same idea as the Lee "custom plug" setup you mentioned). The VLD stems work just fine with bullets that have a relatively short and blunt nose, but they also work with the very long and pointy VLD-type bullets I find myself using more often these days. So I simply replace the standard stem straight out of the gate. Only in one case do I know with certainty that the bullets I was using were actually "bottoming out" in the standard stem, but with the VLD stems, it's simply no longer a concern, even if it wasn't a necessity. They're not stupidly expensive, so it may be worth it to you to swap out the stem, although that isn't necessarily guaranteed to fix this seating issue you're having.
Depending on how many times you've fired the brass, not annealing it could be part of the issue. It is usually possible to feel the difference in seating force necessary with brass that has not been annealed after as few as 3-4 firings. Regardless of what some may think, annealing with a torch setup to dull cherry red in a darkened room does not "ruin" the brass in any way, shape, or form. That is complete disinformation. If you decide to begin annealing your brass, there are torch-based setups available for much less than an induction annealer. In fact, some use the old standby of a simple torch and a socket wrench to hold the piece of brass while it is annealing. I believe the available machines will make the process much easier and more consistent than doing it by hand with a socket wrench, but if you just want to try annealing a few pieces, the socket setup should work well enough with costing a lot of money. Just be warned that there are almost as many opinions about how to properly anneal brass as there are people doing it, so be prepared to filter through the information that is out there if you decide to start annealing your brass.
