That is the question.  Getting my M5 build together (18" barrel with PST Gen II 3-15).  I don't forsee myself having access to anything over 200 yards for the foreseeable future.  For mounts, I'm looking at Warne, PA Glx, and maybe a few others.  With my range and scope choice, I'm assuming 20 MOA is overkill?  OR is it "better to have and not need...."?

My last build had canted folding irons.

I'll probably change back to non canted because I rarely shoot that way.

Sorry, I didn't mean adding canted irons, I meant 20moa scope mounts...

37 minutes up from mechanical center.

My receiver usually take 10 minutes, so with such scope, I would have 27 remaining which is ~750yds. Then there's another ~36 minutes of reticle holdover.

I think +20 MOA isn't necessary for you.

That scope has 75 MOA of internal adjustment. In theory half is above and half below.
Run a ballistic chart and look at how much drop your caliber of choice has.
Compare that to distance you are likely to want to shoot.  

Keep in mind that a plus 20 MOA base raises point of impact 20 inches at 100 yds or double that at 200 yds

You will probably be OK with either a 0 MOA base or a +20 MOA base. But if you might ever want adjustment past say 600 yds the + 20 would give that, but if it’s 5.56 they start running out of energy and light weight bullets get blown around in the wind. If you will never go over 600 yds the flat base is the safe choice.

LaRue. Scope Mount or BOBRO

CANT hurt!

I use 20 MOA mounts on my 6.5 Grendel.  A Friend has farm property to where we can shoot to 1000+ yards.   On my 16” 6.5 Grendel I ran out of elevation around 800 yards.   Having the 20 MOA mount keeps you from having to adjust to the maximum limit on the scope internals.   I use Warne Skel 20 mounts on a couple of my AR’s.    I see guys using canted 20-30 MOA for shooting long range with 22 LR.   I have not had any problem zeroing my rifles at 100 yards with 20 MOA mounts and the cost of the 0 cant and 20 MOA is the same.   I haven’t used 20 MOA mounts on my 223/5.56 AR-15’s but they are not what I will shoot past 500 yards.

I think it really depends on the particular scope and cartridge, 7.62x51, 6 ARC, 6.5 Grendel, 224 V, 6/6.5 CM I say yes.

If you're going to sight the scope in and never dial it.  Go with whatever floats your boat.  

If you have plans to dial your scope for elevation correction then a 20moa mount or base is always the right answer.  

I have a scope on my bolt gun with over 100moa of travel.   The rifle has a 20moa base and the scope sits in 20moa mount.  Still has a 100yd zero and I can dial to almost a mile in .308.

My 308 doesn’t have a 20moa scope mount and I shoot out to 900 with scope adjustment. Not even close to needing that at 200.

Yeah, I went with a 20MOA Primary Arms (what I think is Warne).  Price was right, and it's there if I need it

Try centering the mechanical movement of your scope.

Then bottom the reticle out 5moa from maximum elevation you might dial in.

Now try to find out how much windage you might have available on your dials.    Then compare it to if you had a 20MOA base.

Have shot to 800 yards in a wind with a 300WinMag using 200grn SMKs at roughly 2800fps that requires 5.5MOA of windage.   Still had a 20MOA base because why the hell not.   But imagine not having it and using a different cartridge.

What caliber? Assuming your barrel and upper receiver are in perfect alignment (very few are) 15 moa will have your scope close to mechanical zero at 600 yards.

White Oak Armament sells 10 moa bases which will get you centered closer to 450 yards.

Most new scopes come from the factory centered in their mechanical zero. If you mount a new scope it's not unusual to be off target more than 10 moa in any direction. If that direction is high you are already part of the way done.

If it's low, you may want a 30 moa base.

The whole purpose of building moa into any mount is to get the scope as closely centered in its mechanical zero for the range it's intended to be used at. This improves optical clarity and maximizes windage available at that range.

I have a 15 moa base on a trued and blueprinted .223 bolt action set up for NRA mid-range tournaments (600 yards) which is perfect for that distance.

I think WOA's 10 moa bases are probably perfect for 200/300/600 across the course tournaments.

Many people will never need or use the 20 moa mounts that are so widely accepted. Having your scopes mechanical zero set up for 700 to 750 yards is not how I envision most of my shooting taking place. That's close to .223's maximum effective range.

Most .308's need just shy of 40 moa in dedicated 1000 yard rifles.

I use only 1 20moa warne mount and it's on a 6.5G that I shoot primarily 400-700m.  It holds a decent Bushnell et6-24x50 which has relatively little elevation adjustment available (19mil).  I would run out if dialing for 800m without the cant.

The added MOA is for shots past 800’ish.  Allows you to dial out to 1200-1400 depending on round/barrel length.

Yeah, I picked up the PA/Warne 20 MOA.  Price was right, and "better to have and not need...." and all...

I use Burris XTR Signature Rings.
on the bolt gun i use 30 moa
on the LR308 i'm using the 40 moa
to see how it's going to work out on the gas gun .

Read most of the thread..... here's my take. Might as well do a 20moa mount mainly because you usually don't need the "down" adjustment unless it's for a specific application like a .22 precision where you shoot close and far with a lot of bullet drop. Never hurts to have it and not need it when as your requirements are sure to change!