Some people can't seem to find AR-15 magazines in stock. I did a little searching and came up with the following. Most of these show as being IN STOCK as of the time of posting this message. Hope this helps...
http://www.wideners.com/itemview.cfm?dir=625|626|866
http://www.wideners.com/itemview.cfm?dir=625|626|873
http://www.the-armory.com/shopsite_sc/store/html/product1372.html
http://www.priceinsanity.com/servlet/the-1042596/National-Magazines-R30-dsh-0017-Colt/Detail
http://www.hutsellsports.net/servlet/the-15251/National-Magazines--Colt/Detail
http://www.cactustactical.com/osc/ar15-round-magazine-223-p-83.html
http://www.jgsales.com/product_info.php/products_id/1632
http://www.megahanson.com/product_info.php?products_id=453067
http://dynamicarmament.com/items/AR-15-AR10-MAGAZINES/list.htm
http://www.jgsales.com/product_info.php/products_id/1817
http://www.denverdiscountmart.com/FIREARM-ACCESSORIES/MAGAZINES-AND-LOADERS/39344.html
http://www.wideners.com/itemview.cfm?dir=625|626|866
http://www.wideners.com/itemview.cfm?dir=625|626|873
http://www.the-armory.com/shopsite_sc/store/html/product1372.html
http://www.priceinsanity.com/servlet/the-1042596/National-Magazines-R30-dsh-0017-Colt/Detail
http://www.hutsellsports.net/servlet/the-15251/National-Magazines--Colt/Detail
http://www.cactustactical.com/osc/ar15-round-magazine-223-p-83.html
http://www.jgsales.com/product_info.php/products_id/1632
http://www.megahanson.com/product_info.php?products_id=453067
http://dynamicarmament.com/items/AR-15-AR10-MAGAZINES/list.htm
http://www.jgsales.com/product_info.php/products_id/1817
http://www.denverdiscountmart.com/FIREARM-ACCESSORIES/MAGAZINES-AND-LOADERS/39344.html