Rifle Scopes Unexpected Results at the Range

[George Collins]

Have a friend that is just getting into the long-range game and his gear is very similar to my own. He took it to the range for the first time yesterday. Given the similarity of our gear, we thought that his data card would look similar to my own.

We were wrong.

Here is what we found.

<span style="font-weight: bold">My rifle:</span>
Remington 700p,
Chambered in .308,
Topped with a Bushnell 4200 Elite Tactical scope (45 moa of travel),
Mounted on a 40 moa base,
Using “Low” Burris Xtreme Tactical Rings
Shooting Remington 150 g Core-Lokt bullets,
With my scope at its mechanical bottom,
Zero ~ 275 yards.

<span style="font-weight: bold">Friend’s rifle:</span>
Remington 700VTR,
Chambered in .308,
Topped it with a Mueller APT (73 moa of travel),
Mounted on a 40 moa base,
Using “High” Burris Xtreme Tactical Rings,
Shooting Remington 150 g Core-Lokt bullets,
With his scope at its mechanical bottom,
Zero ~ 450 yards.

Why?

Why was it not possible, given the similarity of our equipment coupled with his scope's greater internal adjustment, for him to establish a zero FAR closer than my own?

 

[Metonymy]

Re: Unexpected Results at the Range

My take would be the difference in ring height. Although some ring brands are closer between Low and High heights, other brands do have significant height differences between each step (L, M, H, XH).

Also, are the tube diameters on your scopes the same?

 

[Trigger Monkey]

Re: Unexpected Results at the Range

Why are you using 40 MOA bases?

 

[1MoreAR]

Re: Unexpected Results at the Range

I guess the ring height has a lot to do with it.You're trying to compare two different rifles,two scopes and two mounts to shoot the same way which very impossible to do. Why worry about all this little stuff,just shoot it and enjoy.

 

[George Collins]

Re: Unexpected Results at the Range

Met - Both are 30mm tubes.

TM - The 40 moa base is to increase the distance I can stretch my rifle out to. Without the canted base, my scope's elevation adjustment would be the limiting factor. The theoretical limit would be < 1000 yards. I wanted to see if I could go beyond that.

 

[dpreston]

Re: Unexpected Results at the Range

your going to have trouble reaching 1000+ yards with a 308 shooting 150 gr. remington core-lokt.

I just throw a 20MOA base on it and go shoot

 

[ORD]

Re: Unexpected Results at the Range

First, I'd worry about some other obvious problems before you get concerned with comparing apples to grapefruit.

1) Why did you both decide to run 40MOA scope bases on rifles equipped with already limited elevation adjustment to run a scope base with that much built-in cant (espeically the Bushy which is EXTREMELY limited at only around 45MOA)?!?

2) If you are both interested in the "long-range game" as you called it...why are you both using $#!T ammo like the 150gr core-lokt wally world special crap that has the terminal ballistic qualities of a flying brick at extended ranges?

Next, all sorts of factors go into disrepancies in performance between two "similar" rifles, including differences in: 1) muzzle velocity from each rifle; 2) ammo (may be the same "type" but what about lot, age, etc.); 3) ring height/height over the bore with each rifle; 4) whether the person with the APT remembered that the turrets are resettable and actually reset them before assuming that they were actually at "zero", etc., etc.

 

[George Collins]

Re: Unexpected Results at the Range

My decision to purchase the Bushnell was based on this review: here.

It used to sit atop my 700p. It now sits atop a .22.

The reason I have a data card for the Core-Lokt ammo is because at one time I had a brand spanking new rifle, had not yet developed a load and was just itching to let a firing pin slam home on something, anything that would make a loud noise. I wrote down the results in my data book.

The reason that my friend was shooting Core-Lokts is because he has a brand spanking new rifle, has not yet had the opportunity to develop a load and was just itching to let a firing pin slam home on something, anything that would make a loud noise. He wrote down the results in his data book.

After we returned from the range, I compared his data to my data.

As I was comparisizin it all out, I said, "Vigh-ollie" as I noticed the previously articulated differences and thought to myself, "Shit! That shit seems shitty. I wonder if the shit ammo we're shootin is the nexus of the shitty results or if our shitty shooting is the reason for the shitty results. Or could it be the shitty scopes? Might it be the shitty difference in our shitty mounts? Might my dumb ass have put my shitty canted base on bass ackwards on top of my shitty rifle?"

All this was going through my mind. As I wuz tryin to cipher it out, I ran out of space on my abacus and thought to myself, "Aha, I got it. I'll make a post on the hide and ask if there is anyone there that might be able to offer any insight to a fellow. They're a polite bunch of fellows, always looking to help a brother out. I think I'll do it. I think I'll throw this bone out there and just see what come of it."

And you were kind enough to offer the wisdom of the ages.

One thing you said seemed kinda strange to me though. Please clarify if you have the patience to condescend once more: Are you sure that different muzzle velocities actually produce dicrepties between POI?

Thank you for your thoughtful, nay, helpful reply and any future sapience you might bestow upon a fellow sojourner, looking to follow the trail you have carved into the jungles of time.

 

[George Collins]

Re: Unexpected Results at the Range

I'm sorry sir but there was one question that you asked of me that I forgot to answer. "Twent like this: "1) Why did you both decide to run 40MOA scope bases on rifles equipped with already limited elevation adjustment to run a scope base with that much built-in cant (espeically the Bushy which is EXTREMELY limited at only around 45MOA)?!?"

I might be . . . scratch that, probably am wrong but the reason I decided to run a 40MOA scope base on a rifle equipped with [a scope with] already limited elevation adjustment is because I was running a Bushy which is EXTREMELY limited at only around 45MOA

The Jews have a saying that goes something like, "To demonstrate knowledge, one will provide an answer. To demonstrate wisdom, one will pose a question."

You sir will have me as your witness for all time if anyone dare question you as being one in possession of exceptional wisdom for the question you posed demonstrates a <span style="font-weight: bold">PRO</span>-freakin-<span style="font-weight: bold">FOUND</span> understanding, nay, mastery of your subject matter.

There was also some dude on here that reviewed the "BUSHY" a while back. I believe he signed off on it. I can't remember exactly who it was . . .low-beam nah, that isn't it . . . dim-light . . . nope . . . low-bright . . . that's not it . . . AAAAAHHH!!! this infuriates me.

CAN ANYONE HELP ME OUT HERE. WHAT WAS THE GUY'S NAME THAT REVIEWED AND SIGNED OFF ON THE "BUSHY?"

 

[LRS_Ranger]

Re: Unexpected Results at the Range

Haha, I love threads like this!

 

[tt350z]

Re: Unexpected Results at the Range

Now that that's out of the way. I want to try to make some sense out of this.

First of all, your rifle has a 26'' barrel. You buddies rifle has a 20" barrel. Yes, it is listed as 22'' but the last 2 inches is the so called "compensator", that IMO doesn't work, but that's not what this is about. Your muzzle velocity should be a bit higher than his, fueling your data card discrepancies with your buddy.

Now what I want to know is, how dd you even zero your rifles? The mechanical zero of you scope is 22.5 MOA (45/2=22.5). I don't know if you know but when you run a base with any positive MOA, it does not add to the total amount of elevation, it only adds to one, up. With your scope bottomed out, your mechanical zero is still 17.5 MOA below that. So realistically your probably at least 10 MOA to high from where your actual zero is.

Even on a 20 MOA base your mechnical zero is only 2.5 MOA from where your scope bottoms out. Depending on ammo and your particular rifle, you may not even be able to get a proper zero. At least you'll have around 42.5 MOA of up elevation out of 45 (still don't know why you chose a 40 MOA, you only gain an additional 2.5 MOA using that base while giving up ALL of your down elevation). A 10 MOA base would probably be your best bet, at 12.5 MOA from bottom.

Of course this is all going by most people's zero at 100 yds...

 

[Dylan in AZ]

Re: Unexpected Results at the Range

TallahallaTarzan, I have to say i thuroughly enjoyed reading your response to comments made in this thread

I mean that with no sarcasm and couldn't help but literally fall out of my chair laughing.

Heck, I'm still laughing! Thank you for this thread and whitty responses

-Dylan

 

[Kevlars]

Re: Unexpected Results at the Range

oh man is this thread funny

 

[Daps!]

Re: Unexpected Results at the Range

Tag

 

[askomiko]

Re: Unexpected Results at the Range

I once had a rifle that shot so much to the right that I pretty much had to use all the windage in my scope just to get it zeroed. Something clearly wasn't machined quite straight in that one. Try swapping the scopes and see what happens.

 

[FALex]

Re: Unexpected Results at the Range

witty banter. Holy shit, this dude rocks! My college-level edum'cation has me thinking, "nay...mastery...cipher..."?! Wut are these words...My head hurts! Damn early morning philosophizin'!

 

[George Collins]

Re: Unexpected Results at the Range

Thank you all for the positive feedback.

See, y'all done gone and made me blush.

Allow me to adjust the parallax on what I see as a paradox and perhaps greater clarity can be achieved for all. Perhaps for me most of all.

As I understand it:

As barrel length increases, MV increases (up to a point).
As MV increases (all else being equal such as LOB and LOS), the strike of the round rises.

Therefore, my 700p with its longer barrel should have greater MV, a flatter trajectory and therefore, if all else were perfectly equal, a more distal zero point with two identical scopes set at mechanical zero (turn the turret in the direction marked "down" until it wont turn no mo).

If all else were equal except for the amount of elevation adjustment available in two scopes and if both were mounted on similar bases (40 moa in this case), the one with the greatest internal adjustment should be able to depress further (45/2 in the "BUSHY" vs 73/2 in the Mueller) therefore allowing for a closer zero.

The difference in the height of the rings affecting zero is certainly not counter-intuitive but I would tend to believe that it would do so marginally at best.

The way I established my zero at 300 yards is by taking a large target, setting it up at one hundred yards, sending one and marking where it hit the target. I then moved the large target back to the 200 yard line, sent one, and marked the target. I repeated this process all the way out to the 900 yard line recording my data as I went.

My friend went through this exact same process except he did it in 50 yard increments.

I had to come up 1/2 moa from the mechanical bottom of my scope to be in the black at 300 yards.

My friend was in the black at 450 yards with his scope bottomed out.

My scope with only 45 minutes of elevation adjustment facilitated a closer zero than my friends did with 73 minutes of internal adjustment even though every factor I can think of says that his should have facilitated a closer zero as well as a greater theoretical maximum range.

What am I missing?

Besides being rich . . . and good looking . . . and world class athleticism . . . I mean what am I missing about this paradoxical day at the range? What factor or factors is it that I have not considered that could nudge my theoretical understanding of marksmanship towards the actual.

 

[aggiesig]

Re: Unexpected Results at the Range

I might be missing the forest for the trees but:

Why are you trying to zero in at your scopes mechanical bottom again? This puts your view at the edge of the glass which means less light, less image quality, and your adjustments generally aren't accurate do to the magnified curvature of the glass.

If you are doing it because you have a 40MOA base that you bought to shoot 1K, then why are you upset that you can't get a zero at 200? My ballistics calculator puts my .308 with 168gr, FGMM is at 39.94MOA at 1K which will put you right at the middle of your scopes adjustment with your optic, that's good if that range is your realistic goal. (that also "calculates" the velocity to be 1159 fps which is fixing to go subsonic and subsequently to shit)

That being said, glass is what it is... yours isn't bad, but it's not what most 600 yard plus shooters would call "good" surely not "great", "top of the line", or "awesome". Part of the reason people pay for a USO, Nightforce, S&B, Premeier, etc. is due to their large range of internal adjustment. I'm sure if you stick around this "game" long enough you'll make that investment as well. I would prefer to put a 600 dollar rifle under a 1500 dollar scope than vice versa.

If you are really set on the long range stuff, save some pennies and start reloading. That's the #1 way to improve accuracy. Don't sweat a 400 yard mechanical zero because your real goals lie well beyond that. If you don't really think you'll ever want to invest alot of time and energy out past 600 yards, then swap your base for a 20 or 0 MOA one. sell your 40 MOA on the hide for a small loss, and call it good.

best of luck to you!

 

[George Collins]

Re: Unexpected Results at the Range

We aren't trying to zero our scopes at the mechanical bottom. We're just zeroing our scopes from the mechanical bottom and then going out from there until we hit some limiting factor regardless of what that limiting factor may be - loss of accuracy secondary to entering the transonic zone, skill level, no further elevation adjustments possible in our scope, whatever.

I bought my gear some time ago. My 700p and Bushnell were meant to be a training platform for some then-as-yet-to-be-determined something else better at some point in the future if I found myself still shooting and desirous of greater performance than this particular platform is capable of providing.

Remington Core-Lokts were the first rounds that I fired from this platform. I recorded the results. Being the consummate neophyte, I had no idea where the rounds were going to go so I bottomed my scope out, shot at a large target at 100 and recorded the results. I next walked the target away from me in 100 yard increments are recorded the results.

At the 100 and 200 yard lines, POI was above POA so I recorded the mil-dot hold under required to be on target at those ranges. When I moved back to the 300, I had the opportunity to make by first elevation adjustment: up 1/2 moa.

When my friend went to the range for his first time this past weekend, he did so with equipment very similar to my own but for a slightly shorter barrel, different rings and a scope that had 73 moa adjustment vs my 45. He went through the same process but for the fact that he was developing his data in 50 yard increments. He bottomed his scope out, fired at the 25 yard line, recorded the results, figgered that if he could hit the little target at 25 yards, he could hit the big'un at 100 so he jacked a round in a pulled the trigger and, as expected he was high. He continued to shoot high until he reached the 450 yard line at which time his POA = POI.

I don't really care that my zero is that which it is.

I don't really care that his zero is that which it is. I don't think he cares either.

What I do care about is learning the "why" behind the "what".

What happened is that a gun driven by a scope that had a substantially greater range of internal adjustment had a more distal POA=POI.

Why is it that two platforms so similar in every respect, but for those variables that seemingly should have produced a more proximal zero for his gun, producing such counterintuitive results?

Why?

Aziz - Thank you sir for your suggestion. If we haven't resolved this issue by the time we go back to the range, I will certainly be willing for us to strap my Bushnell on his stick to see what happens.

 

[dieselten]

Re: Unexpected Results at the Range

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TallahallaTarzan</div><div class="ubbcode-body">
Why is it that two platforms so similar in every respect, but for those variables that seemingly should have produced a more proximal zero for his gun, producing such counterintuitive results?
</div></div>

Your rifles may have been exact off the shelf duplicates but that will not dictate how they will shoot or zero. And for those who think the difference in ring height is the contributing factor, well...

The things you are not taking into consideration are tolerances, hi quantity/low cost manufacturing and barrel harmonics. Each rifle vibrates differently and the muzzle is pointing to a slightly different place at the moment the projectile leaves. Plus, the bores are never concentric to the outside diameter on factory remington rifles, nor are the threads concentric to the outside of the receiver. Yours could be pointing up and the other one pointing down with both rifles locked in a vice and the receivers leveled by a NASA engineer with $10,000 woth of tools. Then add both of these scenarios together and see how far apart two identical mass produced rifles shoot.

 

[Dantrom]

Re: Unexpected Results at the Range

I'm tagging this to refer back!!

 

[former naval person]

Re: Unexpected Results at the Range

As dieselten says...the vibes can make the difference. Furthermore, the barrels and and ammmo can vary a bunch. From what little bit I know...if you want to shoot way out there...the 155 Palma bullets, and the 175 plus grain bullets will do it. Speed and BC are king. If you REALLY want to shoot at distance...start reloading, work up loads for your own rifle. Every one is different. A 20 MOA base is sufficient for .308...even with a POS scope. Don't handicap yourself with over the over the counter crap ammo. I have friends who do just that. They load crap bullets over crap surplus powders with crap cases that they never trim...and they sit at the range, calling the shots..."Hey, you were off at 6 o'clock by 18 inches...then next, "Off at 3 o clock by 2 feet...then hey...you hit that dead center...then, next shot..."Off at 3 o clock by a foot." Without precision in components, loading practices, and techniques...you are pissing into the wind. JMHO

 

[aggiesig]

Re: Unexpected Results at the Range

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TallahallaTarzan</div><div class="ubbcode-body">We aren't trying to zero our scopes at the mechanical bottom. We're just zeroing our scopes from the mechanical bottom and then going out from there until we hit some limiting factor regardless of what that limiting factor may be - loss of accuracy secondary to entering the transonic zone, skill level, no further elevation adjustments possible in our scope, whatever.

I bought my gear some time ago. My 700p and Bushnell were meant to be a training platform for some then-as-yet-to-be-determined something else better at some point in the future if I found myself still shooting and desirous of greater performance than this particular platform is capable of providing.

Remington Core-Lokts were the first rounds that I fired from this platform. I recorded the results. Being the consummate neophyte, I had no idea where the rounds were going to go so I bottomed my scope out, shot at a large target at 100 and recorded the results. I next walked the target away from me in 100 yard increments are recorded the results.

At the 100 and 200 yard lines, POI was above POA so I recorded the mil-dot hold under required to be on target at those ranges. When I moved back to the 300, I had the opportunity to make by first elevation adjustment: up 1/2 moa.

When my friend went to the range for his first time this past weekend, he did so with equipment very similar to my own but for a slightly shorter barrel, different rings and a scope that had 73 moa adjustment vs my 45. He went through the same process but for the fact that he was developing his data in 50 yard increments. He bottomed his scope out, fired at the 25 yard line, recorded the results, figgered that if he could hit the little target at 25 yards, he could hit the big'un at 100 so he jacked a round in a pulled the trigger and, as expected he was high. He continued to shoot high until he reached the 450 yard line at which time his POA = POI.

I don't really care that my zero is that which it is.

I don't really care that his zero is that which it is. I don't think he cares either.

What I do care about is learning the "why" behind the "what".

What happened is that a gun driven by a scope that had a substantially greater range of internal adjustment had a more distal POA=POI.

Why is it that two platforms so similar in every respect, but for those variables that seemingly should have produced a more proximal zero for his gun, producing such counterintuitive results?

Why?

Aziz - Thank you sir for your suggestion. If we haven't resolved this issue by the time we go back to the range, I will certainly be willing for us to strap my Bushnell on his stick to see what happens. </div></div>

I follow exactly what you are doing, and why you did it. I think the "why" is simply you have 2 different rifles, with different harmonics, different optics manufacturers that have different "mechanical zeros" and different mount setups. You could not only switch the optics on the rings, but switch the rings while keeping the same optics on their respective rifles and see what happens. I bet there is a small fraction of difference in the pitch of your optics due to slight variations in elevation from your rings, or hell even your base, or even the alignment of your base with your action, or any number of things. without going through every piece with a micrometer it would be hard to know exactly if things are pointed the wrong way, or if something is out of spec or whatever...

I think you could set this up as a pretty detailed multi-variable study and burn up SPSS in the process, or you could just smile and say "it is what it is" and move on with it.

 

[vman]

Re: Unexpected Results at the Range

IMO you should have a standard zero moa base and your friend should utilise a 20moa base.

 

[George Collins]

Re: Unexpected Results at the Range

My friend got off work early today and even better, I didn't even have to go in. When he got off, he asked if he could come to my home range. I eagerly agreed for him to do so for I was anxious to put Aziz's advice into action.

The first thing I did was take the Bushnell off the 10/22, remounted it to my 700p and using my brand new shooting bench for the first time (thank you sir) I fired a single round of shitty 150g Core-Lokt from 100 yards with my scope bottomed out.

The impact of the bullet was 6 inches high. (EXACTLY where it impacted the last time I shot shitty Core-Lokt ammo from my 700p using my "bushy" to drive it.)

Next, we each took our scopes off, I mounted the Bushnell onto his VTR and shot one round of shitty 150g Core-Lokt at 100 yards.

The impact of the bullet was 11 inches high. A 5 MOA difference.

It gets kinda muddy here but I'm from Mississippi and we'uz kinda use't wallerin in th'mud. So here goes:

We returned to less soggy quarters and phoned a mutual friend and told him of the results. He knows yet another feller that has a VTR chambered in .308. Dude told us that dude told him that the 700VTR is machined to less exact tolerances than the 700p and that such a variance was not uncommon with the VTRs.

I don't know about the machine specs Remington chooses to use between the 700p and the 700VTR but even when using the same scope, we achieved markedly different results.

So there it is. It's the gun. Or so it would seem.

My friend ordered a 20 MOA base before he left my home. Problem solved (I think). Thank you Aziz and all of the other folks who had constructive things to say.

 

[aggiesig]

Re: Unexpected Results at the Range

I wouldn't jump the gun on this one (pun intended), there are still several other variables that I don't think have been addressed including differences in rail/ring dimensions. also take a look at this post, some interesting research on barrel "whip" when firing...

http://www.varmintal.net/aflut.htm

2 drastically different barrel profiles... This could account for a decent percentage of the variation.

 

[cvedrick]

Re: Unexpected Results at the Range

Check me on this, you have a PSS with 26" round medium heavy barrel set into a H-S precision stock with full length aluminum chassis.

He has a VTR with a 22" trianguler varment/target weight barrel mounted in a B&C stock with an aluminum action bedding block.

Seems to me the PSS would be more rigid.......

Is your ammunition out of the same box or having the same lot number?

Have you tried match grade ammo?

Forget about your zero's how do your groups compare?

 

[sgtadm]

Re: Unexpected Results at the Range

thanks for all the help ! got a new base and scope rings and that did the trick . now to building out a load .