Advice Needed: Mounting Optics on AR15 Flat Top

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Feb 16, 2003
I "pulled the trigger" and bought a Bushmaster M4 A3 today. Total newb at AR's, so I could use some basic advice.

After I get through playing with the irons, I'd like to mount a rifle scope that I have in the cabinet. And I'll likely buy a red dot for it later.

Question: Do I need any special hardware other than weaver mounts to mount a scope or dot on the picatinny rail that is on the rifle?

I see some "riser" type devices out there. Are they needed, or are they optional for mounting to the picatinny? Chief benefits of risers?

Any tips or suggestions re: mounting optics on a flat top are appreciated.

the ideal height above bore for an AR15s sights is pretty close to where Eugene Stoners team placed them on the carry handle
go to Wilson combat and look at their 1 piece mount and ring setup, have one on my ar15 and it is great.................
ARMS,GG&G, and Larue all make very nice (and expensive) scope mounts for both 1" and 30mm tubes. However, if this is a scope you just have lying around, I'll be a bit presumptious and guess that it's not a very expensive one. Weaver rings will fit on the picatiny rail, and may be a much less expensive option.
Getting Weaver rings high enough to see through the scope might be hard.

If you think you will be serious about keeping a scope for your AR get a good one piece mount.

I like LaRue, ARMS and GG&G are also good.

A throw lever detachable mount is nice because you can remove it without tools.

Depending on the scope's eye relief and whether or not you use the nose to charging handle cheek weld you may need a cantilever mount (extends in front of the receiver).

If you end up purchasing a backup iron sight think about what other things you would like to put on top of the rifle. If it is not low enough in the folded position you will have to remove it for some scopes/sights.

You also might consider cutting off the front part of your detachable carry handle, leaving the portion with the rear sight. This will leave you with enough room to mount a dot type sight in front of your rear sight with a backup that you have already paid for.

Hope this helps.
if you want to go cheap I might suggest cdnn has a riser mount for a flat top. with standard rings it will be at the same height as the irons. and it comes off with 2 big thumb screws. but I do suggest a different set of rings than what comes with the mount. it is only $20 for the mount shipping is $9.99 no matter how big the order is.

Depending on the scope's eye relief and whether or not you use the nose to charging handle cheek weld you may need a cantilever mount (extends in front of the receiver).
That's one reason I just use irons (the other being I dont have a whole lot of desire to put a scope on it). I havent looked very hard to be perfectly honest, but I cant find a carry-handle mount that moves the scope far enough forward for the correct eye relief or a riser/ring assembly that will do the same, leave room for a flip-up or fixed rear sight and still allow me to put my nose to the charging handle without getting a bruised forehead or black eye. One thing I've thought about doing is getting getting the Scout Rail from RRA and cutting enough off the back to make room for a DPMS rear sight on my upper, that way I can mount the scope far enough away for the correct eye relief and still keep my nose to the charging handle with the irons. And if that doesnt work out I'm only out about 60 bucks for the rail I cut up.

I wish they would make a version of their Scout Rail with an A2 sight in it, or make the tac handle longer (either way, it would pretty much be the same product in terms of function). For some odd reason, I dont like the extended rail(?) they offer. Just a bit too tactical for my taste I guess.

I just realized that I've put more thought into this than I thought...
Aimpoint in Larue mount...EO Techs are improving but they have a ways to go to catch up IMHO

Larue also makes mounts for a regular scope...

But your fron sight post will likely be in the way without a riser
I am doing the Aimpoint with Arms mount along with a spacer for Co-witnessing.. :cool:

I did some "studying" and this was my decision...

A lot of other choices await.. :)
The front sight post really does not get in the way.

On most scopes with magnification it is too close to see.

On something like an Aimpoint I prefer cowitnessing with the iron sights.

Your mileage may vary. ;)
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