OK, I have a Bushnell DMR2, 3.5-21x50, G3 on it's way.  It'll go on my AR/SR/LR 308 build.  I have a Magpul UBR stock, for now.

Where do I start with scope mounts?  I don't see the scope leaving the gun, so doesn't need to be detachable, but anything will be looked at.  I guess something high enough for the 50mm objective and charging handle clearing the rail.  Oh, and 34mm tube.

Geissele

You're going to want a cantilever mount and I highly recommend a one piece. If you go to Eurooptic.com they have a mount selector system that will get you the right mount and you can verify it if you use their chat function and ask them to double check based on your application. Make sure they say it will fit your scope before you hit the buy button.

I have used a variety of scope mounts, Leupold, ERA-TAC, JP Rifles, etc., and haven't got a bad one yet from Eurooptic.

Most mounts that are around 1.5" height will clear the 50mm. A cantilever is probably what you are looking for. My scopes all have 34mm tubes and 50 or 56 objectives. I'm not familar with the scope you are running, but moving it forward with a cantilever helps with cheekweld and eye relief.

All my mounts up to this point have been LaRue QD's. I found myself in the same boat in that the optics aren't swapped or moved. Geissele mounts look good. Aadmounts do too. Seekins mounts seem really nice and their rings have good reviews.  I needed another mount recently so I looked at a bunch.  I ended up ordering a Seekins and it should be here next week.  If it's anything like all the other Seekins I have,  then it should be nice. I've had a lot of suggestions about the Burris PEPR, but no experience with it. Quite a few have stated being very pleased with theirs.

What budget are you working with?  There is a pretty big spread on price. Do you need/want any cant? Prefer vertical or horizontal rings or could care less?

Just a heads up,  Seekins and a lot of places showed their MXM mount and others backordered.  I found what I bought at SWFA. Shipped quick,  just waiting on it now.  Actually looking forward to receiving it.  They're showing 1 left in stock at $189.95 (Just letting you know if the MXM interests you and you are having a hard time finding one). A lot of the 34mm mounts mentioned seemed to be backordered.

FWIW I'm running Steiner Military scopes and they are pretty long.  The DMR 2 looks more compact and may give you other options. Good luck and keep us informed of what you decide to go with please.  Experiences and impressions are always good to hear.

I have the same scope coming and will go with a JP scope mount. https://www.jprifles.com/buy.php?item=JPFTSM-34

OK, I'm new a this.  I'm not quite understanding the "Cantilever 20 MOA" application.  Does it tilt the scope up?  What does this do for me?  I know this is basic info for you guys, but for me.......

Sorry for the basic questions, but I'm running with my first build, in an area I'm not too knowledgeable about, and needing a little help.

Thanks

Don't apologize,  questioning and learning is always a good thing.

Cantilever pushes the scope forward for better positioning and eye relief.  The 20 MOA cant slopes the scope down in the front basically reclaiming some of the elevation adjustment.  Shooting longer distances has more elevation required than some optics may have available and the canting helps address this. There are a couple good articles on this.

First build... hmmmm... this is great fun stuff.  Sounds like you already have the needle in your arm.  

Can you direct me to those articles?

And, pushing the 50mm objective down, clearance issues?

Yes down and no I have not had clearance issues. Clearance will be addressed by ring or mount height. My mounts are all 20 MOA and have both 50mm & 56mm and I've had no issues. I'll see if I can find the articles and IM them to you.
IM sent.

Rob what mount is that?

DOH!!!!   Nevermind,  sorry.  Just read the whole post instead of a skim read while at checkout. Apologies.

That scope will have more usable travel than most cartridges that fit in an AR308 will need. Unless you plan on shooting past 1400 yards you won't need the 20 MOA cant. Cant isn't necessarily bad but it can add height and weight to the mount depending on the manufacturer. Also, the AR308 has a longer top rail which negates the need for the cantilever designed for an AR15. Personally I'd look at mounts designed specifically for the SR25/AR308 platform such as LT111/807, ADM Recon S, etc.

I don't see me shooting to, or past 1400 yards.  I was unaware of scope mounts specifically for SR25/AR308 platforms.  I guess where I'm sitting at now is, I have all the parts and pieces to assemble the rifle.  I'm somehow stuck on the scope mount, especially in regards to scope height required vs cheek weld/eye level.  How does one really determine what height of a scope mount to buy?  I would hate to spend $200+ on something that will not work.

Actually, I think I need to wait until I get the thing built.  I was surfing the web again, and came across the LT104.  Which looks like it may provide proper eye relief, depending on what spacing I have on my upper.  I think I will stick with LaRue, just to keep the search narrowed down.

AR15 scope mounts use a cantilever design to accommodate the eye relief of modern scopes while maintaining a reasonable cheek weld. SR25/AR308's have a longer top rail than an AR15 so the cantilever is redundant. The LT104 is for an AR15 and the LT111 is for an OBR/SR25/AR308.

The AR308 and AR15 have a similar rail over bore height and, generally speaking, most mounts are in the 1.5" neighborhood. However, depending on the mount the 34mm tube can increase the scope height. Your preference will depend on the shape of your face. I prefer 1.40" if I can get it and can really feel the height at 1.60". ADM for example uses the same lower mount section for all scope tube sizes and increases the ring height for larger tubes so their mounts will be taller for your scope. Most of the mount manufacturers provide specs, I don't see them on LT's site so you might want to email them.

The LT111 will work with some scopes.  With the length of the DMR 2 there should be no problem. My Steiners are all ~3"+ longer and the LT111 had that eyepiece sitting back past the charging handle. Was the reason I sold the LT111 off and went with the LT745.

I like Nightforce, Larue and Geissele mounts. I generally use a 1.4 to 1.55" centerline cantilever mount. I still use cantilevers on AR10 platforms as I'm used to shooting with my head a ways forward.

Geissele in front, Nightforce center and Larue rear. All of these are 34mm tubes. I've got a spare G mount for my next 34mm scope

I'm running a 20MOA cant non-cantilever Spuhr mount (3601) on my LRP-07.  I have a PRS stock on the rifle.  Without the horizontal adjustment of the stock, I would not be able to obtain proper eye relief on the scope.  So, you can solve the eye relief issue in multiple ways if it comes to that.

BTW.. the spuhr is pricey.  But it is a damn fine mount.  The built in bubble and mounting wedge helped me justify the cost....at least in my mind.

Yeah, I like the Sphur design, but they're spendy!

Riddle me this:  what should cost you more?  Your scope mount or your bipod?  

Seriously though, by the time I bought the JP, Vortex AMG, and Atlas bipod, what was $100 difference for a mount?  Didn't hurt that I also got the Spuhr used for $300.