Detritus said:
what if any advantage SWC Vs RN bullets ... 200gr Semi-Wadcutter over a 230gr round nose bullets in .45acp.
is there a difference in inherent accuracy? easier to make PF? economics (price)
If you look at the comparison picture above of MBC bullets, the 200 gr SWC bullet is essentially a 230 gr RN with some lead removed from the nose leaving the contact points for reliable feeding. Various Dardas/MasterCast/MBC/ZCast 200 gr SWC bullets have reliably fed/chambered in all the 1911s I have loaded for (Kimbers, SA, RIA, Citadel, Sig, etc.).
I think 200 gr SWC is inherently more accurate than 230 gr RN due to having the same length of bullet base/bearing surface that engages the rifling but with better weight distribution (more weight towards bullet base) for greater rotational stability in flight.
As to making power factor (PF), to make 165 PF, you need to push 230 gr bullet to 718 fps while you need to push 200 gr bullet to 825 fps which is very doable with many popular powders. One downside with 200 gr bullet is with some temperature sensitive powders like W231/HP-38, you would need to use more powder to make the same PF on colder days and many match shooters use 170 PF for their match loads for this reason.
An example is while 5.5 gr of W231/HP-38 would make PF on warmer days, you may need to use 5.8 gr on colder winter days to make the same PF with 200 gr bullet. With heavier 230 gr bullet, this is less of an issue and you can always use less temperature sensitive powders like Titegroup for 200 gr bullet.
And of course lighter 200 gr bullet will cost less than 230 gr bullet.