Multiple seating dies or just one?

OK, this is somewhat silly question but here's the situation - I dialed the seating die on my Dillon 650 so that it seats the 200gr LSWC bullets to the desired depth. Now I'm thinking about trying different kinds of bullets (JHP, 160gr LSWC, etc) which require different seating depth. So I'm wondering if there's a way to put some marks on a die so that I can easily switch between different seating depths or will I be better off getting a die for each type of bullet and replacing them on the toolhead? I'm a bit concerned about the repeatability. How do you guys solve this problem?

I would adjust my dies.

David

I seat SWC bullets off the shoulder, it's an RCBS with a custom stem specific to that style of bullet.  For FMJ or JHP bullets I use Redding Competition die.  With a lock ring on the die replacing them is very repeatable.

I have a dummy loaded round for each bullet. Back off the seater, put it in the shellplate, run it up and adjust the seater to match. Putting an empty piece of brass in each position of the shellplate helps.

I use four different complete 45 ACP toolheads for Dillon 650/750, one toolhead for 1050 (loading 200gr #68 and Brazos 180 gr SWC) and one Star press dedicated to loading Brazos 160gr SWC and 185gr #130 bullets.  Most seating dies on Dillon's platform are Redding or Hornady micro adjustable, and have stems modified for loading particular bullet profiles, and so are the PTUs in powder measures. Please also keep in mind that replacing just seating dies or seating stems for different types of bullets is not the only change necessary.  Crimp dies have to be adjusted as well.  And that is even bigger drug on time needed to change from loading i.e. SWC to JHP bullets.

Yeah, I can hear comments that this might be excessive. And I will not argue about.  It came about through years of reloading and experimenting.

AP

I have one seater that I never have to adjust irregardless of SWC bullet weight/ design. I do have to back it out 1-1/4 turns for 230 RN and RN profile like the Nosler/Zero 185 jacket. 

Take your seater plug and counterbore it with a 3/8 drill. It will now seat most bullets by the shoulders, not the point. Thet also seat straight. I learned this from Ed Masaki. Not sure who invented it though.

There are two issues here.  Matching the seating stem to the bullet, and adjusting the die.  The match of the stem to the bullet is going to depend on the particulars of the stem and the bullets.  Full wadcutters and semi-wadcutters can take substantially different stems than jacketed hollowpoints.  You can modify your stem yourself, have the die manufacturer produce a custom stem, or buy from the variety of stems they offer.  To my knowledge, Redding offers a variety of stems for popular bullet types.

To adjust the die, a micrometer-type seating depth adjustment is ideal, but there are alternatives.  Redding offers the competition seating die with a micrometer adjustment.  They also offer a micrometer adjustment conversion for their standard dies -- it doesn't add all the features of the competition seater such as the floating stem, but it does add the indexed adjustability on the seating stem knob.

For non-micrometer adjustment dies, I have simply made index marks on the stem adjustment knob and the die body with a Sharpie.  I have to keep track of the number of full turns and the precision with which I can repeat adjustments is probably just 1/8th of a turn, but it helps me get in the ballpark quickly and then I can finish the adjustment by checking a few cartridges with calipers.

For finer adjustability, shims can be used under the die lock ring.  This is more typically used to add or subtract one to a few thousandths when bumping shoulders on rifle brass.  It may not be practical for a much larger change in seating stem adjustment, but that will depend on just how big the difference is and whether or not a suitable shim can be sourced and made to work.

Another alternative is a click-adjustable die lock ring.  There is one from Whidden that can move a total of a tenth of an inch in 100 clicks of 0.001". It does not have an index so if the movement is large, it can be a lot of clicks to count.  There is another adjustable die bushing that is available on the Hood presses.  It does have a (color coded dot) index but has less range of movement.  Again, these are primarily intended for small movements of a resizing die.

Adjustment of seating depth isn't just for different bullet profiles.  Even if I am seating to a crimp groove, there is probably a range of at least 10 thousandths of an inch different depths that can be tried and if I am not limited to a groove I might try depths in increments of a few thousandths for some distance in either direction as long as I also had the means to test the results.