AR10- scope mount questions

[SpeedyR]

Ordered a 308 AR but it'll take a little while to get here. My plan is to use it for some longer range shooting (some friends are getting into precision rifle shooting and thought it might do double duty with some good handloads).

here's my question- I am ordering a 5-25x50 Burris XTRII scope. I will get some 34mm rings for the scope, but how important is it to have a 20MOA base? It seems that's the traditional setup for a 308 bolt gun and I've seen that as some options for the AR's but it doesn't seem to be as common. At what distance will having raised base come into play?

from what I can see, if I want to shoot over 600 yards, I'll have to do some traveling... but just was curious to get some feedback if I should just use a standard mount or look for a 20MOA version.

lastly how important is the forward mounting that's common on most AR mounts? My primary 556 AR is an LMT so it's monolithic from front to back.

TIA!

 

[Rbs]

If your shooting using hold over you may not need a 20moa base. If you want to put your cross-hairs dead center on a target at distance then a 20moa will be much more advantageous to you.

You have essentially nothing to lose but much to gain with a 20moa base.

Im actually trying to sell my standard American Defense 30mm base now to get a 20moa AMD base.

 

[kuduman]

All bases should be 20 MOA by default (but are not). I'm looking for 30 and 40 MOA bases, for shooting past 1000... I guess it matters not if you aren't shooting beyond 300. But where's the fun in that?

Rbs is right-- you may not need the offset, but you have nothing to lose by getting one with 20 MOA, and much to gain since you'll be shooting nearer the mechanical center of your scope.

This is a glaring problem on DPMS' SASS and Ruger's new chassis rifle-- flat bases. Do they really not have anyone on staff that knows better than that?

 

[SpeedyR]

This is a glaring problem on DPMS' SASS and Ruger's new chassis rifle-- flat bases. Do they really not have anyone on staff that knows better than that?

actually the new Ruger base is 20MOA that's what got me thinking. I doubt I will do much "long" range shooting with it, maybe out to 600 yards (CMP new facility maybe)? I will probably try to get one of the Rugers in the 6.5 once the initial frenzy is done (another round to buy dies and brass for, huh?).

I need to see what the elevation adjustment is on the scope. As a friend told me when I asked him the same question, he suggested I look at the adjustment on the sight and see how it compares to the ballistics of the rifle/round/bullet to see how much adjustment you need. I.e. if you have 80 MOA adjustability, and you only need 40MOA to reach 1000 yards you should be very close. Plus with a 16" barrel I don't think I'll be reaching out further than 700-800 yards anyway.

just checked the scope is 90 MOA so +/- 45MOA from center. so if my thinking is correct at 800 yards with FGMM 168r HPBT with 100 yard zero is roughly 28-30" drop? might get that within the range of the adjustments on the scope??

too much thinking, my head hurts. lol.

 

[BHJ]

Your scope should perform it's absolute best when it is optically centered. If most of your shooting is out to 500 or so (like most folks) a canted base is a waste of space that has you starting out way way up the ladder from center at a 100 or 200 yard zero. Get a good set of high or extra high rings (whichever you need to clear the objective and put your eye in the proper position) and rock out.

 

[kuduman]

actually the new Ruger base is 20MOA that's what got me thinking. I doubt I will do much "long" range shooting with it, maybe out to 600 yards (CMP new facility maybe)? I will probably try to get one of the Rugers in the 6.5 once the initial frenzy is done (another round to buy dies and brass for, huh?).

I need to see what the elevation adjustment is on the scope. As a friend told me when I asked him the same question, he suggested I look at the adjustment on the sight and see how it compares to the ballistics of the rifle/round/bullet to see how much adjustment you need. I.e. if you have 80 MOA adjustability, and you only need 40MOA to reach 1000 yards you should be very close. Plus with a 16" barrel I don't think I'll be reaching out further than 700-800 yards anyway.

just checked the scope is 90 MOA so +/- 45MOA from center. so if my thinking is correct at 800 yards with FGMM 168r HPBT with 100 yard zero is roughly 28-30" drop? might get that within the range of the adjustments on the scope??

too much thinking, my head hurts. lol.

I plugged in some guesses into my phone-- it's not 30" at 800 yards, it's 30 MOA. 240 inches. 20 feet.

But anyway, it'll work without the slanted base. But I'd get one anyway.

Thanks for telling me the Ruger has a slanted base-- I've read two reviews that did not mention that. Since they didn't, I figured it wasn't. Good to know.

There's the CMP place, and there's also Gunsite Hills in Lexington. Both about the same distance from Atlanta, I would guess. GSH has some steel out near 800, though it's in the woods at that point. And the owner is cantankerous, but he does know his stuff. Riverbend gun club has steel out to 600, and is open to the public a couple of times a year (like last Saturday).