And the reason for using a plated bullet is?
The reasons are multiple.
First there is cost. Extreme's 125 grain flat points run about 8 cents each currently if you factor in their 15% discount. Total shipped cost for 1500 was 117 dollars. Compare that to FMJ and it's about a 12 cent per bullet savings. Even without a discount you can find 125 grain plated for about 9 cents per bullet.
Second is cleanliness. First, compared to lead they are a LOT cleaner shooting. One local range is considering banning any ammo loaded with lead because the smoke generated by the lube clogs up their HEPA filters a lot more quickly. They haven't done it yet but anyone shooting lead hears about the 10K per month filter costs and is strongly urged to change to plated bullets. Second, if you are loading lead you really should be wearing latex gloves to prevent absorbtion through the skin. You should also be wearing a respirator when shooting. Because treatment for lead poisoning isn't at all inexpensive and it's also not totally effective. Finally, at handgun velocities copper jacketed bullets just don't foul barrels. The ONLY time I had a badly fouled barrel it was due to the use of some Blazer LRN 38 spl..
Finally, about all those concerns about damaging the plating or "overspeeding" plated bullets. I've run 165 grain 40 caliber bullets from RMR at 1100 fps with no issues at all. BTW, this is a practice load for my carry choice of Speer's 1150 FPS rated 40 caliber Gold Dots. I've also run a lot of Rainier 125 grain flat points in 38 spl. at 1050 fps and never had any issues with leading. IMO if you don't get stupid with Magnum loads you really don't have to be concerned about "overspeeding" the bullets.
I also pull a bullet anytime I'm using a new to me brand and have yet to see one single bullet with the plating damaged by my crimps, either taper or roll. Bullets from HSM, RMR, Berry's, Rainier, and now Extreme are well plated with a coating that is capable of withstanding a rather decent crimp. BTW, my "moderate" roll crimp is visually a match for that seen on American Eagle SJSP 357 Magnum ammo. Some may call this a Heavy crimp but since the plating is intact under 20X magnification I don't see any need to change my crimp. I'll also point out that in many many thousands of rounds fired I haven't had one single instance of a fouled barrel when shooting plated bullets.
Finally, I'm just too old to stand in an unheated garage casting bullets. Even though I live in Michigan and did a lot of snow skiing when I was younger I have come to really HATE being cold.