Nice discussion. It's been a while, but I thought I might try and revive it a bit.
I just finished my 3rd 460 Rowland conversion (two pistols and a carbine). The first pistol conversion was done on a Springfield XD Tactical whereas the second used a Kimber Custom TLE II as a base.
In addition to the 460 Rowland kit, I put a tungsten guide rod, a trigger kit and extra power mag springs into the XD. Since I am in CA, the comps need to be permanently attached to the barrel, which on an XD makes cleaning inconvenient as you cannot get the barrel out of the slide. I bought the XD kit from http://www.460Rowland.com.
I wanted a Wislon Combat Hunter in 460 Rowland, but I can't get one in CA, hence the Kimber.
I purchased the kit for the Kimber from the great folks at Clark's http://www.clarkcustomguns.com/rowland.htm and it dropped right in, everything fit and ran. I haven't done any real tuning, but I found that the 8 round Kimber Tac Mags worked the best, followed closely by the Wilson 8 round ETM. I tried some Chip McCormick 10 round mags, as well as either a Wilson or a Kimber 10 round mag and suffered FTF issues. I shot handloads of 185 HP and 230 FMJ. The Kimber Tac Mag was the only magazine to run 100% flawlessly.
I have to say that I hated installing the 24lb recoil spring. The video on Clark's website makes it look really straightforward. Perhaps its because this was my first 2 piece guide rod, but it gave me fits, and as a result I have put off cleaning (for shame). Is it just me, or does that spring pose a challenge to anybody else?
I also had an issue where the slide stop backed out. Anybody else see this?
I put some laser grips on this as well, and they stopped working after about 100 rounds; it turns out that I needed to re-seat the battery, this may have been poor installation on my part.
As far as shooting, it definitely grabs attention. Since I reload (and providing I can find the brass after firing) the cost is just slightly more than 45ACP. This means I can afford to shoot 150 rounds and share. The most common remark I get is "I'm getting one of these!". Unbeknownst to me the woman 2 lanes down was shooting for her first time and apparently the 460 Rowland's bang made her jump quite a few times. The guys next to me were drooling and chasing my brass for me. I was on lane 7 and I found brass in the stall of lane 1. It must have bounced off the back wall.
I am now in the process of customizing the Kimber.
(FYI Starline Brass https://www.starlinebrass.com/brass-cases/460-Rowland-Brass/ is now taking back-orders for shipment of 460 Rowland brass in early May.) $255 / 1000