If I order a Bushmaster A3 upper, but do not order a carry handle to go with it - do I run the risk of experiencing a problem with "fit" if I order a Bushmaster carry handle at a later date ?

Thanks.

No...I just gave my A3 carry handle to a good friend with a grizzly lower...

its all picatinney so the fit will be just fine!

Dont spend the extra money if you plan to use optics....use the extra cash for good BUIS

Thanks.

Yeah, that's kind of what I was thinking. I have 2 A2's - and I like the look, but I am going for a flat-top with my next build. I've got a lot of expenses with the BUIS and Forearm, so I was hoping I could wait a while before picking up the carry-handle.

you shouldnt have any trouble with sticking with the same manufacturers parts.I have a colt handle for my flattop Bushy and its made for the colt higher FSB so I needed a taller front sight.I got it for $30 bucks from a buddy wanting to rid himself of it and I cut it down for a BUIS.Get a BUIS and dont spend the money on a handle unless you get it cheap.If you like A2 then get an A2 upper other wise get a good BUIS.If I didnt have this one I would have the ARMS#40.The home made one serves me well and I still have plenty of room to mount my aimpoint while  still keeping the regular A2 rear.