Could a canted base hinder scope's performance at a shorter range?

[dirtdigger]

Hey all! I 'm finally putting together my Hog Hunter .223 that was purchased late last year and am making a decision on a base as we speak. My other sticks are equipped with 20 MOA bases (Weaver predominately) and I would keep it that way. Not too long ago I have read online something along the lines of that a scope, theoretically at least, can be a lil more blurry visually at a shorter range when mounted on a 20-30 MOA base due to the elevation knob being cranked a bit to compensate for the cant and the shooter not looking through the optical center of the scope where it is the sharpest as a result. Any credibility to this in your opinion gents? It kinda makes sense to me but then I don't know how a scope works exactly to tell the truth so it might have been just a bunch of bull after all. I 'm going to be around 300 yards or so with this gun in the foreseeable future. Thanks for your replies!

[foxx]

I have heard that as well, but I don't believe a decent scope has that much distortion at the extremes of it's vertical limits. It seems to me if it did, then long range tactical shooters would make more of an issue about it than they do. I believe Burris makes a bigger deal of that possibility than is warranted when selling their Signature Zee rings. It's a bit of unnecessary hype to sell their product. Those offset internal rings are a good product, it just isn't necessary for all the reasons they state. Of course, I could be wrong.

[dirtdigger]

Oh.. I didn't know that about Signature Zees. I always thought those inserts were only to provide the needed tilt for a scope when using a flat or two piece bases and running out of vertical scope adjustments with those.

[sixonetonoffun]

I think the consensus is optically centered zero is better when possible.

[dirtdigger]

My question then is, which base would I be better centered optically with in my case? As I stated the distance is pretty much 300 yards that I will be shooting at most of the time. The rings are low (0.80" space from top of base to the center of the tube). I know the question may be loaded a bit but I had to throw it out there anyways:p

[sixonetonoffun]

Bore sight it to see where your at. Most likely a zero will get the job done better at the range your planning. Some scopes won't have enough travel to zero @100 with a 20 moa rail.

[LoneWolf]

Another big thing to consider is the parallax adjustment available on the scope. If you're trying to shoot at very short range like 25yds or under and the scopes parallax adjustment is 50yds-infinity than it's going to be more blurry. With a quality scope that has the adjustment range you are looking for you shouldn't see much of an issue.

Some precision rifle match directors think courses trying to shoot tic-tacs at 8 yds is a good idea (Exaggerating a bit). In most cases I don't see a real issue as long as you have proper eye relief and all that. For shots under 100yds I leave my zero and figure out what the hold under or over is so the exact adjustment and optical center of the scope will not be an issue.

[foxx]

Yes, to all of above. However, you can't have your scope optically centered at all distances. To me, the question is more about does the scope allow you to see well enough and without error throughout its entire vertical range. If it does, then there is no need to be concerned about it. I believe quality scopes DO allow for this. If they didn't, then tactical shooters who shoot accurately at multiple distances would make a bigger issue about it. If scopes did not allow for that, then the solution would be to have moveable mounts rather than turrets that move the scope's reticles internally. At one time, that was necessary. It isn't any longer. So go ahead and use whatever mount or cant devices you need to get he ranges you need. The optical quality is fine throughout.

[Jamie]

There is two things not mentioned here....

1) if you need 20 MOA for 300 yards then something is broken somewhere.

2) A lot of times at the extreme edge of adjustment, the adjustments become error prone. I have had more than one scope that would start moving left or right with up or down adjustments until is was about 12 clicks from stop. Then they would work normal

Buy ANY quality base and go shoot.

[dirtdigger]

OK, thanks again for the responses!

@Jamie: No, nothing is broken so far (as I haven't even shot this gun yet and don't have all the necessary hardware for that yet) and there is no real need as of yet to have 20 MOA base for this set up. I wanted to get it in case I move to longer distances with this gun at some point in future so I don't have to worry about changing it later but didn't want to compromise the performance of the scope at 300 too much. I may be splitting hair here though and thinking too much into it.. I did hear about some scopes having faulty reticle adjustments toward the end of their travel.

@foxx: I do realize that a scope can be optically centered at only one particular distance on a certain set up and am still curious which base would get me closer to that at around 300-400 yards since this is where I will be at most of the time in the near future.

@LoneWolf: Parallax adjustment starts at 25 yards I think on the scope that is going on this gun. May be 50 but it is well under 100 yards for sure, gotta double check what it is exactly. I never found myself in a situation that required shooting that close up to now though.

@sixone: Can't bore sight as I don't have the base yet. I have a couple of other sticks with 20 MOA bases and I was able to zero the scopes that are on 'em - not particularly expensive ones. I like and keep my zeros at 200 on .223 guns though. That way my POIs are relatively close at both 100 and 300 when dead holding which is convenient if a shot needs to be taken in a hurry. Did you mean a 0 base will get me closer to my goal @300?

[Jamie]

I may be splitting hair here though and thinking too much into it..


This is what was on my mind when I first read your post.

You should not need to go to a 20 MOA base until you are shooting past 600 yards and depending on scope, maybe not even then.

[foxx]

I agree with Jamie. The "optical center" you are trying to make optimal use of is much larger than you are giving it credit for. I imagine that area, for practical purposes, is roughly 80% of the lens surface. When you use the outer extremes of the turrets' adjustability, you are still within that 80% range. However, there can be PHYSICAL limits to how far up and down the reticle can be moved when adjusting for right/left (and the vice versa).

Imagine one tube inside another... as you move the inside tube to the lower portion of the outer tube, you have less vertical space available due to the curve of the outer tube. So the scope's vertical and horizontal range of movement is limited at it's extremes, but if the outside tube diameter is large enough, it allows more than enough space for the adjustments the shooter is looking for. That is why some shooters require 30mm outside tubes as opposed to 1 inch tubes. None of that, however, is related to the quality of the image at the extremes.

Have confidence in the image quality and accuracy regardless of your adjustments. If you want to be able to use your scope at longer range in the future, go ahead and get the canted base or the Signature Zee rings. (they serve the same purpose). Practically speaking, in all likelihood you won't need them. Might help, won't hurt.

Caveat: There is the possibility that if you use the canted base, there is not enough PHYSICAL vertical adjustment of the scope to allow you to get a 100 yard zero. (maybe 1 inch high at 100 yards, when "bottomed out". ) Depends upon how much vertical adjustment your scope has built into it. Also, the height of your mounts affects this.

I know how you feel, BTW. I have, in the past, had the exact same concerns. :)