Back in June, I solicited this board for information on the late Brian Bilby’s “Pocket Rocket†compact 10mm. At the time, I was specifically looking for information on what spring weights he used, and how he set them up so they would run and not pound themselves into slag. When I started my quest for info, I was under the impression that his “Pocket Rocket†was an OACP in 10mm. It was soon pointed out to me that it was NOT an OACP, but, in reality, a CCO in 10mm. That is, an OACP frame with a Commander top end. The idea of a 10mm CCO had been on my mind for a couple of years, and I put together a parts sheet for a future Caspian order based upon the Bilby guns and the Dan Wesson 10mm CCO. I was all set to pull the trigger on the Caspian order when another opportunity was dropped into my lap. While cruising the firearms auction sites, I stumbled across a new, in the box, Kimber Compact Stainless Series 1 in .40 Smith. Crunching some numbers, I figured out that I could convert this Kimber to 10mm about a thousand dollars cheaper than I could build a Caspian-based 10mm CCO. Besides, a 10mm CCO had already been done and it worked. Could a Kimber Compact (4†barrel) be converted to 10mm, run reliably and not self-destruct under a steady diet of 10mm? I didn’t know, but I was eager to find out!
After taking delivery through my friendly, courteous and helpful local FFL (Thanks Jason!), I stripped it down to figure out what I needed to do. My first mission was to get it to run as a 10mm. After I got the bugs worked out, I would pretty it up a bit. I sent the barrel to Bob Hunter at Hunter Customs to rechamber from .40 to 10mm. While I was waiting on my barrel to come back, I reviewed all of the info I could find on setting up a 10mm 1911, and it occurred to me that a whole bunch more is known about making a 10mm 1911 run than when Mr. Bilby was building his “Pocket Rocketâ€. Fifteen years ago, the common solution to slow down 10mm slide speed was a heavier recoil spring. Today, the EGW flat-bottomed FP stop and heavier mainspring coupled with a heavier recoil spring tames the 1911 10mm down a good bit. For this little beast, I went with a 25 pound mainspring, the EGW flat-bottomed FP stop, a Cominolli “Frame Saver†guide rod set up and a heavier-than-stock recoil spring. The recoil spring is where I hit my first snag. Unlike the 4†Springfield Compact 1911s, the Kimber uses the same recoil spring as a Colt OACP. As the good folks at Wolff’s explained to me, a recoil spring that is rated for 20 pounds in the OACP would be rated for something around 18 pounds in the Kimber Compact. I was looking for a recoil spring weight in the neighborhood of 24 pounds, given the short and light slide of the Kimber. Wolff makes a Kimber Compact-specific XP recoil spring, but it was still only rated at around 22 pounds. While I initially ran one of these springs, I eventually went with a shortened 24 pound Commander spring.
In addition to the heavier springs, guide rod set up and EGW FP stop, I also installed an Ed Brown “Hardcore†slide stop, just to be on the safe side. The extractor didn’t look like a tool steel part, so I swapped it out with a Colt Delta Elite extractor I had on hand. More on that later.
My initial range test was pretty exciting! I was half-expecting things to come apart and to have parts flying all over the place. Nope. The little Kimber-Beast ran like a top! During my initial range testing, I used a Colt factory 10mm mag, as well as a couple of Metalform 10mm magazines. I had hoped to have a Metalform 10mm OACP magazine on hand, but it was back-ordered. The fact that Metalform made 10mm OACP mags was one of the reasons I started this project.
Over the course of two days, I ran about 300 rounds through it, consisting of PMC 200gr FMJ, Silvertip 175gr HPs and my standard 10mm practice load of 8.6gr of Power Pistol behind a Remington 180gr FMJ. When Bob Hunter rechambered my barrel, he told me to run only factory-level ammo; no real heavy, hot-rod stuff. That was fine by me. I had originally intended to run nothing hotter than Silvertips through it anyway. (Then I discovered “Double tap†ammo, but that’s another story.)
During the initial 300 round shakedown, several things became apparent. First of all, while it had some recoil to it, it was actually quicker to return to target than my Lightweight OACP. Second of all, it was ACCURATE! I was expecting around 4 inches or so at 25 yards. HA! With the PMC and my handloads, I was getting groups of just over an inch, hand-held, at 25 feet!
I also discovered, or confirmed, that slide speed would be a problem. About 250 rounds into the testing, the hook on the Colt Delta extractor sheared off! This surprised me a bit. While it wasn’t a new part, it sure didn’t have THAT high of a round count. I took a break and fitted a new Ed Brown extractor and also installed a cut down 24 pound Commander recoil spring. The rest of the shooting went off without a hitch.
As this is written, I have around 750 rounds of mixed ammo (to include 50 180gr Double Tap practice loads, just to see what would happen…no ill effects to report!) through the Kimber Compact 10mm. All in all, this has been a great project, and I learned a bunch. After I finished the initial testing and was satisfied that it wouldn’t blow up, I replaced the lockwork with EGW tool steel parts, fitted an Ed Brown grip and thumb safety, a Videki/Greider trigger, a Baer mainspring housing and a Heinie rear sight. After I got done with it, I turned it over to Dave Helton of DVC Custom, and he serrated the front strap and bead blasted it for me. I also had him tweak the trigger a bit. This is how it turned out:
My intent is to replace the springs every 500 rounds, and the buffers on the Cominolli as needed. So far, the buffers hardly have a mark on them.
The only glitch it has at the moment is a sight issue. I replaced the front sight with the tallest Kimber has to offer, and it still shoots 4†high at 25 yards. I suspect that sometime in the not-so-distant future, I will be talking to someone about a custom front sight so this little beast can shoot to point of aim.
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Since he has a 10mm Commander, his was one of the brains I picked when I was initially going to build a 10mm CCO. That 10mm Commander was one of the guns that kicked me over the edge. 
