interesting, if very expensive: http://www.pilkguns.com/menu_ar15.shtml
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We all know that one the best ways to practice in the off season is an air rifle and it certainly develops your skills, but there still numerous fine points of muscle memory and sight acquisition that cannot be the same as your Service Rifle, at least with traditional air rifles. But we decided that we could give you everything your want, the same as your target AR-15 has them already. The exact sight picture and EXACT trigger feel along with the exact feel of your buttstock weighted just the way you like it against your own cheek. How can we do that? Half of the answer is already in your hands, your personal AR-15 lower receiver. The other half is the new BF-17 upper that houses an air rifle action made by Pilkguns. The BF-17 upper uses actual AR-15 components like an A2 upper, front sight mount, charging handle and handguards. It also has National Match ¼ minute rear sights matched to a top quality .177 Lothar Walther barrel to put your shots in the X ring where we know you have the talent to place them.
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Initial pricing is $750 for the BF-17 upper with ¼ minute rear sights. Contact us for lower pricing with standard rear sights. A discount of $50 is available for the first 15 purchasers who place a $250 deposit.