Re: AIAE or GAP Crusader ?
They are very similar, but the mkI (fde skins) was my first. Up till about a yEar ago I had never shot an AI. I tried a few rounds through a friend and liked it soo much I went online to shop for one. I found a deal on the mkI on a thread on arfcom precision rifle forum for the rifle, a leupold mkiv, 5mags, starlight case, ansld some other accessories. I bought it 6am that Monday when the shop opened. I ended up loving the rifle (solid .3 moa @ 300yards) but wishing I had 10 rnd mags. Tacpro had a sale at the end of last year and had the bottom rifle for 2800, so I bought it. I shot the factory barrel for a while and I was half moa but I decided I wanted to try a bartlien on it. Right now it's wearing a 22" med Palma tightbore 1-13.7 to 1-13 gain twist. I haven't shot it enough to tell how it is shooting yet, but initial results have been good.
Once I have a handload for the mkII that shoots like the mkI does, I'll probably part with the mkI in favor of a second mkII or an AW... Probably a 6.5-something or a 7-08.
On the barrel, yes they "interchange" but you'll need an action wrench (thunderbeast arms makes a less expensive alternative to a factory ai wrench), a torque wrech capable of at least upto 125lbs, and a barrel vise. It's not difficult on an AE but requires removing the action from the chassis.