I have 4 of the 6" 10mm long slides. A Glock 40 MOS, a Remington Hunter, a Kimber and soon to be delivered Nighthawk Chairman. The Glock with the reddot is great to shoot, reliable, inexpensive in comparison and accurate. You can get a threaded barrel for it. In 1911s, the Remington shoots great but I've had feed problems as it semi-consistently won't return to battery on the last 1-2 rounds in any given magazine. I may have to send it to someone reliable for work. The Kimber works flawlessly, no issues and is reasonably priced. Of course I can't wait for the Nighthawk to be delivered. It will comes with their IOS system so I'm probably going to put a Vortex reddot I have laying around unless I want to splurge on a RMR. There are less expensive, mostly Philippine-made 1911 10mms out there, but I have no experience with them. You can probably get a 6" threaded barrel for any of time, but I'd strongly recommend gunsmith fitting unless you are experienced with barrel fitting.
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