OK, my turn. I also recently purchased a Kimber Polymer (BUL M-5) pistol and have had the same feeding problems discussed above. I share in the frustration and agree that this "expensive" 45 should be RELIABLE. On the other hand, it's the most accurate 45 I've ever handled out-of-the-box (I would have dumped it by now if it weren't for this). The feeding problems I'm experiencing have to do with the high capacity magazine for the most part. Initially, I had problems with a misfeed every 10 rounds or so with either the high-cap or 10 round mag, but a call to Kimber improved this. Apparently the prior owner placed a shock buffer. The Custom Shop at Kimber advised removing this which I did with much improvement. The second problem had to do with the slide stop which they replaced with no questions asked. I also asked them to replace the magazine catch (made from the same polymer as the frame) as it looked "chewed-up" to me, and check-out the high-cap magazine. The magazine was returned with a new spring and follower. The mag catch was replaced "no questions asked". At this point, the slide stop problem was resolved, but I continued to have problems with the high-cap mag. Currently, this mag is being replaced for a new one at Kimber. With these mags going or $115 a piece, I'm not willing to just buy extras. All-in-all, I have had a GOOD experience with customer service at Kimber (talk to George), and I'm sure they know about the problems with the Polymer. Thus far, they have been working to make things right at no cost to me and I have yet to send them the gun. I've been trying the simple fixes first. If the problems continue, the whole gun goes back for repair. I won't even get into the technical details regarding why I think these problems occur as I am not a gunsmith. I certainly have some ideas if you want to email me. In summary, the Polymer has problems, Kimber has been diligent about resolving the problems, and I haven't lost faith in the company yet. If they ultimately screw me, you'll hear about on every message board on the net!!
P.S. As far as I know, Wilson doesn't make double-stack mags that will fit the Polymer model as suggested above.