ar and scopes

[smyrna]

I've actually researched this a little and talked to a few folks but I've gotten conflicting opinions, so I'm hoping some of the experts here can shed a little light on this for me. Thanks in advance...
What's the general consensus on mounting a scope to a flat top AR regarding the following...

Should extra tall rings be used that mount directly to the rail or use riser blocks and then rings?
If riser blocks are used, do you favor a one piece riser or two individual riser blocks and why?
What about the one piece mounts with integral rings? Pros/cons?
Total height above the rail to the center line of the optic should be about 1.5" to give a cheek weld similar to using iron sights...right? Wrong?
Picatinney versus Weaver rings-are they different enough to be critical?

[FlynJay]

I went with a one piece riser block and regular tall rings. My riser block is easy to remove for mounting of a red-dot or carry handle (the red dot is also on a one piece riser block). When I put the scope back on it is within 1 MOA. If you don't plan on taking the scope off regularly then it really doesn't matter.

Total height should be whatever is comfortable and repeatable for you, but in most cases is about 1.5".

[The Annoyed Man]

I mounted my Burris XTR 3-12x50 directly onto a varmint rifle's flat top receiver with 1" high Burris Xtreme Tactical Rings, and it works great. No separate base is required. Also, having a Magpul PRS stock helps to ensure the prefect cheek weld each time.

[stealthcrf]

Riser is not needed with magnified optics. I find medium rings to work fine on the rail, but thats my personal choice.

[The Annoyed Man]

Riser is not needed with magnified optics. I find medium rings to work fine on the rail, but thats my personal choice.

It might depend on objective lens diameters. A 3-9x40mm scope might not need to be mounted as high as a 3-12x50mm scope in order to keep the scope bell from interfering with the rifle.

[stealthcrf]

TAM, thanks I forgot about that.

[smyrna]

Riser is not needed with magnified optics. I find medium rings to work fine on the rail, but thats my personal choice.

It might depend on objective lens diameters. A 3-9x40mm scope might not need to be mounted as high as a 3-12x50mm scope in order to keep the scope bell from interfering with the rifle.

My question with risers and scope height was not so much about the scope clearing the rifle, but maintaining a similar sight plane as the iron sights. (Not interested in co-witnessing with iron, just maintaining a similar sight plane.) I picked up an AR one time that had a scope on it and although the scope cleared the rifle when shouldered, it just didn't feel right...I felt like I had my head all sideways just to see through the scope, like it was too low.

So by the responses, I take it that either rings mounted directly to the flat top, or rings mounted to a riser mounted to the flat top are acceptable. One is not preferred over the other? Just a matter of preference?




I

[FlynJay]

Yes it is all about preference. The only reason I have mine on a riser block is that I routinely switch between scope, iron sights, and a red dot and I like the fact that I really don't have to re-zero the scope when I put it back on.

[The Annoyed Man]

Riser is not needed with magnified optics. I find medium rings to work fine on the rail, but thats my personal choice.

It might depend on objective lens diameters. A 3-9x40mm scope might not need to be mounted as high as a 3-12x50mm scope in order to keep the scope bell from interfering with the rifle.

My question with risers and scope height was not so much about the scope clearing the rifle, but maintaining a similar sight plane as the iron sights. (Not interested in co-witnessing with iron, just maintaining a similar sight plane.) I picked up an AR one time that had a scope on it and although the scope cleared the rifle when shouldered, it just didn't feel right...I felt like I had my head all sideways just to see through the scope, like it was too low.

So by the responses, I take it that either rings mounted directly to the flat top, or rings mounted to a riser mounted to the flat top are acceptable. One is not preferred over the other? Just a matter of preference?

Exactly. The height of the scope bore ought to be set whatever is comfortable for you. It makes no difference (within reason) how high that is above the barrel bore, as long as the scope is zeroed to the point of impact at some predetermined range (100 yards, 200 yards, etc.) of your selection.

Another variable to consider... a buttstock with an adjustable cheek weld height, such as the Magpul PRS. Keep it low to match the line of sight for your iron sights/red dot sight, and raise it up for your scope if your scope's dimensions require rises that put the scope bore above the line of sight for the iron sights. That said, I have found it personally more practical (although a fair amount more expensive) to simply have two ARs with different setups — one a varmint rifle with a 24" heavy barrel and a good scope; and the other a carbine with iron sights and an Eotech.

[smyrna]

That said, I have found it personally more practical (although a fair amount more expensive) to simply have two ARs with different setups — one a varmint rifle with a 24" heavy barrel and a good scope; and the other a carbine with iron sights and an Eotech.

Cool!