Point being - he mentioned lead being the least costly component.
In my 35 plus years of reloading, I've found that the brass is the most costly individual component.
Reloading low pressure rounds, like the .45acp and .38 spl and .45LC and .44 spl. allow for much longer case life/more reloads before the brass can no longer be resized w/out the case neck splitting.
All of these calibers operate at less than 20,000 pis. A couple, the .45acp and the .45 LC, are around 13,000 psi.
Higher pressure rounds, such as the .357 magnum, .44magnum, 9mmLuger, .40S&W and 10mm, operate in the 35,000 psi range - w/the 10mm going up to 37,500 psi.
Higher pressures = more case expansion = shorter case life.
Shorter case life = increased cost since the brass can't be used as much.
I'm simply curious how many reloads he can get per case before the case can't be reused.
It has nothing to do with the dimensions of the case - it's all about case life.
The more often you have to replace the brass, the higher the cost.
That can be offset somewhat by a lower price per individual bullet.
Berry's sells a plated .401 155 grain bullet for 33.78 per 250
Berry's sells a plated .452 230 grain bullet for 40.04 per 250
The .40/10mm is $.135 per round to reload as an individual component.
The .45 is $.160 per round as an individual component.
That's a savings of $.025 (approx) per round for the bullet component.
Starline sells 10mm brass for 85.50 per 500
Starline sells .45acp brass for 85.00 per 500
The 10 mm brass component is .171 per round.
The .45acp brass component is .17 per round.
The bullet/brass component is:
.30 for the 10mm
.33 for the 45acp
1000 10 mm loads would run $300
1000 .45acp loads would run $330
If you took the same 100 cases of each and loaded 1000 finished rounds and you got 10 usesout of each case, then the 10mm is a clear money saver.
OTOH - if you only get 10 uses out of the 10mm and you get double that number out of the .45acp, then the .45acp is the clear money saver.
The next 1000 rounds of .45acp will run $160
The next 1000 round of 10mm will run $300 - due to having to buy brass once again.
Bear in mind - this is both greatly simplified and does not account for lost brass nor does it take into account the cost of powder.
I'm using Starline bras as an example and Berry's bullets as an example because that's an apples to apples.
My actual .45acp loads run quite a bit less than the above since I use a .452" lead bullet.
Berry's sells a 230 gr hard cast lead bullet for 61.24 per 500 or - .122 per round.
That would skew the .45 price & make it cheaper.
OTOH - the OP may very well cast his own 10mm bullets, which would reduce his cost to pretty much whatever he had to pay for scrounged lead & the cost of electricity to run the melting pot.