[Ricochet]

Best 1911, is arguably a TM. Upgrade the inside before the outside. Longer barrels don't usually change distance. That gun will be accurate to 50-100 feet, period. Making the external of the gun bigger is, as mentioned above, redundant, or counterintuitive at any rate. What you gain in stability will be minimal, what you gain in weight and function loss will be high. If your goal is to have a 1911 or pistol in a carbine kit then fill your boots, but if you're looking for an effective airsoft gun on the field then leaving it as a pistol and utilizing it as a close quarters/backup secondary will be better and buying a proper rifle will be VASTLY superior, even stupidly so. Airsoft technology and the applied physics just are what they are. Certain platforms will always dominate others and they don't follow the advantages/disadvantages of their real steel counterparts. For instance an airsoft sniper rifle won't outshoot an airsoft carbine necessarily for accuracy and distance. A pistol will never make a good long range weapon, because they just don't, with maybe the TM MK23 being the exception. You'd still be better of with a proper AEG or whatever anyways.

So in retrospect, no one here is going to recommend you going down the road that you're going, hence the responses. If you had asked, "hey, what's the best 1911? I want to make it into a carbine kit", then someone would've recommended brands. But really what your question sounded like, coupled with your title asked, "Hey, I want to create something useless and stupid for the field and want to know how to impossibly make it do something it won't?". Ask for a 1911 carbine because that's what you want, that's what you'll get, ask for a Ferrari by getting a skateboard and starting out by smashing the wheels off of it and that's what you'll get.

Best, competitive, useful, functional, enjoyable, effective, etc, equals NOT AN AIRSOFT 1911 WITH A CARBINE KIT.