Looking to mount a scope on my flat top AR.  Will be used mainly as a varmint rifle.  Are the one piece mounts with integral rings the way to go?  Will be using around a 4-12x scope with a 40mm obj.  Seems everyone is going with some special ARMS mount or something like that or rings with levers, but I don't see what advantage if any that offers.  Also wonder what the point of using a riser block with rings is, when you can go with the one piece integral mount.

I put Leupold Mark 4 super high rings on my Bushmaster flat top with a Zeiss 4X14 44mm and they are great but a little pricey.

I like Armalites 1 piece mount. I have RRA and Model 1 one piece mounts also. The Model 1 and RRA place the scope to high for a good cheek weld for me. The Armalite sits closer to the bore line and I can get a good cheak weld.

A riser block and rings would allow a person to use windage adjustable rings like Millets or Burris Z rings and others so the scope would have close to even L-R windage adjustments on the scopes turrets when set up properly.

I have a new RRA one piece mount for 1 inch tube scopes, if you're interested.

If that is a Leupold 4-12, you may consider a scout rail to extend the flat top, then mount low or med. rings to that. I have a couple 4-12 A/O  VX-II's  and need plenty of room. I am waiting on an upper now with a flat top reciever being built for 'mid range' varminting. It will wear a GG&G scout rail and there will be no question about trying to get a good sight picture with a 13 1/2" lop.  hope this helps.

    Be sure to consider eye relief as well as height - the Picatinny rail on a flat-top may not let you mount the scope far enough forward for a comfortable position, especially in prone. I use an extended riser (1/2" high) made by Accuracy Speaks (available direct or from Brownell's) combined with standard-height rings.  There's now a similar one available from Compass Lake Engineering.  This gives me an extra 4" of rail and lets me mount a Leupold 6.5-20x50 LRT (a rather long scope) and gives me the option for an extra 15' of built-in elevation for long range work. I'm using Burris Signature Zee rings - they are inexpensive and work well, even though they don't have the macho look many seem to like.  A big advantage of the Signature rings is the floating insert that self aligns - no need to lap the rings to avoid stressing the scope tube.

I have the Armalite one piece on my V Match(20). This mount is rock solid, positions the scope at the perfect height for me and sits far enough forward to allow proper relief, and still obtain a nose to charging handle cheekweld. Also it didn't cost a small fortune. I have an 8.5-25X, Mueller Eraticator scope with the illuminated red dot in the center of fine crosshairs. This scope has a 50mm AO and still has plenty of clearance. Breaking it in this weekend.

Ditto, Armalite mount, for same reasons as above.

I needed to install an ARMS S-EX rail (super extended) on my flat top so I could move the scope rings farther forward.  There was/is no scope mount that moves the darned thing forward enough to provide adequate eye relief, especially while prone.  None of the shorter rials were long enough.  The Armalite mount was too short, too.  Once I installed the rail, I simply used Leupold MkIV rings to mount the scope.  There is still enough room behind the scope to install an iron sight.

It was a simple solution to an otherwise difficult problem.