Haven't seen a airsoft M40A5 to date. A M40A5 is a Modified M40A3 (extended mag, NVG Mount, And a Flash-hider/Suppressor mount). I'd look for a M40A3, then modify it to a M40A5. Your odds to find this are much higher but still aren't too good.
I am sorry, Battlefield 3 has gotten to my mind, I meant an M40A3. And no not a real steel haha. I was wondering if anyone on here had a modded one (upgraded or not) that would be willing to sell because I am really interested in having something different than everyone else.
I would also mod it with rails, etc. to make it appear as an M40A5.
If you are modding savvy and very patient I'm sure you could fit a McMillan stock onto a VSR system. I believe that a rifle is only different if you yourself make it different instead of just buying the final product. BUT that is just me...
If you are still interested, I have an M40A3 I'd sell you for $600. Its a fully upgraded(Laylax) VSR-10 that is installed into a real steel Bell and Carlson stock. I have a nice leather sling and two different scopes that could come with it: one is a 3.5-10x40mm and the other is a 10-40x50mm. Let me know!