That's very well possible. They may also be plated thicker too. I've not heard of people saying the same things about them that almost everyone says about Extreme or Berrys plated.
For me, if I'm going to be paying FMJ pricing, I may as well get a true FMJ and not have to handle them with kid gloves loading them and finding a workable load. The "normal" plated bullets are easy to screw up during the loading process and then you have to find a load that groups well which can be difficult. Example: I tried the 230 RN Extremes in my 625. It's a shotgun pattern with every charge I tried. I can drop in a Bayou 230RN and any powder charge in the load range will shoot decent groups, just some a little better than others. I think that Bayou, S&S, Missouri, and ACME are all using the same coating (Hi-Tek) and there's probably more since Donnie at Bayou starting selling it alone. I've just found coated lead to be all around easier across the board in all of my guns than plated when it comes to getting a good grouping load.
The plated Speer bullets are like 8¢/bullet. I haven't ordered them yet as I'm still tempted with coated bullets.
I also have undersized throats in my m66 and am wondering if it would just be better to buy a reamer. I've opened up throats in .45 Colt Rugers with emery cloth but figure I have enough .38/.357s to justify a tool.
You got my curiosity up and RMR has the 135 Speer at 8.4 cents if you buy 2k. Not bad. You can get Precision Delta 130 FMJs for 9.5 cents apiece or Montana Gold 125 FMJs for 9.3 in bulk. The Speer won't have any exposed lead on the base if that is a consideration. My last buy from ACME was around 6.5 which is why I haven't just went solely to FMJ.
I like any cast lead bullet to be about .0015" larger than my barrel's groove dia. ideally. Some guns like even more but you're usually fine at .001 - .0015. The old school way was to slug your barrel and run you chamber throats up to .001 to .0015 larger than that. That was especially true with .45 Colt guns. Hell, back in the day different manufacturers used different dimensions on their barrels! Luckily that's all in the past and barrels today are so uniform they don't even need to be slugged to see what they size at.
When S&W went away from pinning their barrels and used tighter interference fit threads, those tend to squeeze the barrel dia down at that point and open to their true machined size past the frame. If that constriction is enough reaming your chambers won't really matter a lot, the barrel will just do the same thing as a tight throat. With all that said I've yet to have a big problem with non-pinned barrels, but I don't shoot PPC or bullseye. USPSA and ICORE occasionally.
My understanding is the RMR 135gr Speers were overrun. They were used for Lawman #53757 ammo that was a training surrogate for the Gold Dot rounds and has been discontinued. Speer CS told me they've never sold this bullet as a reloading component to consumer channels, so once RMR's supply is gone, you probably won't see them again.
.
-----------------------------------------
Not another dime.