I know a lot of you have 18.5" Mossberg 590A1's. I had the blues that I couldnt get a decent magazine extension like you could for the Remington 870. Choate Machine and Tool has JUST come out with +1/+2 (more on that later) extension for the 590A1. Two companies had made +1 extensions before, Vang Comp and Nordic, and both of those were north of $75. The choate one is $45 and includes a new spring,orange follower, and sling swivel clamp. Its parkerized just like the 590A1 finish. I ordered mine last thursday so it should be here pretty today or tomorrow. The cost with shipping was $52. Not my pic, its from shotgunworld forums The extension is flush with the end of the barrel so officially its a +1 but with the original follower and possibly a more compact spring it might hold a full 7 in the tube. I'll post more when I get mine. AFAIK these are a limited run right now so if you want one, call Choate Machine and Tool and ask for part #02-04-01.