In building my SHTF rifle, I had trouble deciding whether to use my SBR registered lower and go with a 11.5" barrel, or a more traditional 16" barrel. I am planning on having a supressor for this gun, and attached to the end of the 16" makes it very combersome for manuvers, and very front heavy. However, the 11.5" barrel does not have a reliable accuracy (at my skill level) past 350yds. So, I started wondering - DOes anyone make a barrel extension which threads onto a barrel to increade the otherall length? Granted, I know there wouldnt be as much barrel uniformity, and the accuracy wouldnt compare to a standard barrel, but it would still offer some benefit, and would be a lot lighter and more manageable than carrying around an entire extra upper, not to mention easier and faster to attach. Can Anyone help?