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Forum Index > Optics > A word on Sightron tracking vs other optics

A word on Sightron tracking vs other optics

18 Mar 2020
@ 09:14 am (GMT)

Nathan Foster

This post is to educate my readers (or remind my regular readers) at to the virtues of controlled tracking (e.g. Sightron) as opposed to spring resistance only tracking (e.g Leupold VX / Swaro etc).

I have previously talked (LR shooting book and here on the forums) about the issue of dialing up using a spring type turret. As the turret reaches its upper limits (dialed right up), the spring tension may become loose. Under these conditions, a scope, regardless of its pedigree (e.g Swaro) may for example shoot 3 to 5 MOA when dialed for a long shot. It therefore pays to test your scope at these upper settings. It may also pay to additionally test the upper setting yearly or bi-yearly.

To test the optic, work out how far you intend to shoot (max range). Lets say thats 1100 yards. Next, work out how much come up you need for this (lets say 35 MOA). Having sighted in and zeroed the rifle at 100 yards, dial up your 35 MOA and fire another group. Now here is the key - you need to check both the travel (was the scope true to clicks) AND THE GROUP SIZE. If the scope employs an opposing spring without any form of locking, the group may be large. If the group is large, the scope is useless for long range. If so, put the scope on a regular hunting rifle rather than a long range rig.

There is in addition to this, a further problem that concerns regular hunting rifles rather than long range rifles. If your scope bases or receiver are slightly out of line, it may force you to utilize a great deal of windage or elevation in order to zero your regular hunting rifle. If you have to dial right up or to the right to simply get the rifle zeroed at 100 yards, it may render the spring loose. As a reader relayed to me today:

My accuracy Saga's are over! It was the scope! I pulled the new 2.5x8x36mm Leupold and slammed on a Leupold 1x4x20mm I had since the 90’s that has always performed well on heavy recoiling rifles. Bam, my groups went from 6+MOA to under 1 MOA. It was then that I realized that the internal travel adjustment for the 2.5x8 Leupold was only 72 MOA and the 1x4 was 110 MOA. I had maxed out the elevation turret while zeroing it and because of the stress under recoil from the .35 Whelen, it would shift its POA every shot - hence the ridiculous groups.

Most of you know that I have some bias towards the high end SIII Sightrons. I am not completely biased but there are features of the SIII that I find highly useful. I hope this post helps to explain some of my reasoning.

To conclude, try to remember elevation and windage extremes as a potential issue when addressing accuracy problems. Some form of controlled tracking is generally more reliable than basic opposing spring tension within a turret (flat turret screw against a round erector tube).

Canted bases, canted rings (e.g Burris) and solid bases (which can be shimmed) with dovetailed windage adjustable rings can also be used to address various problems. Canting is not simply the domain of the long range rifle.

Replies

1
18 Mar 2020
@ 11:35 am (GMT)

Scott Struif

Re: A word on Sightron tracking vs other optics
Sightron no-doubt has a patent on ExacTrack.
18 Mar 2020
@ 12:29 pm (GMT)

Magnus Vassbotn

Re: A word on Sightron tracking vs other optics
Interesting post. I was only vaguely aware of this issue from before, as I have never really been caught out with it (so far, touch wood). But now of course it will become another deciding factor for a scope. Could you (and others) please write a short list of which brands/ models use which design? That would be very useful. If it's in any of the books, I haven't gotten to it yet, but a chapter reference will do.

18 Mar 2020
@ 05:18 pm (GMT)

Scott Struif

Re: A word on Sightron tracking vs other optics
Page 112 of the long range hunting book
18 Mar 2020
@ 07:26 pm (GMT)

Magnus Vassbotn

Re: A word on Sightron tracking vs other optics
I was thinking of a systematic list of known brands/ model lines, not a mention of the concept itself, like in the book. Somethimg that can serve as a kind of buyers guide.

These brands use springs: xxxx

These brands are mechanical: xxxx

And so on.
19 Mar 2020
@ 02:41 am (GMT)

Scott Struif

Re: A word on Sightron tracking vs other optics
From Sightron's FAQ page:

Q: Do you put the same tracking system in the SV, SII, SIIB "Big Sky", SIII LR series and S-TAC series?
A: Yes, these all come with Sightron's ExacTrack Precision Windage and Elevation™ system that guarantees repeatability and accuracy.
19 Mar 2020
@ 09:03 am (GMT)

Nathan Foster

Re: A word on Sightron tracking vs other optics
Hi Scott, thanks for quoting the page number.

Yes, Exactrack is on the SII up. But over the years I have found that many folk struggle with the smaller 25mm body scopes with their smaller turrets. When I make a post etc, I try to keep a number of factors in mind - eye relief, turret usability, robustness of the scope body, country of manufacture etc. Hence the recommendation of the higher end SIII. Second to this (from Sightron) comes the S-TAC 4-20 for long range users. The 3-16 duplex also has great merit for 400 yard rifles.

I am currently using a budget S-TAC 4-20 on my .500 A-Square, a cartridge based on the 460 Weatherby case necked up with the body blown a considerable way forwards. The recoil is so high that I have to either wear a mouth guard or pack gum between my teeth. The scope has proven reliable and tracks very well.

The S-TAC has certainly proven reliable. This is one of the few budget scopes I would recommend. Sightron would surely disagree with me and state that folk need a range of budget options. When I was young, my thinking was shaped by NZ author Graham Henry (see also Cartridges book - .338 Lapua). Henry didn't mince words and felt that if a person could not afford something, it was a sign that they needed to work a bit harder and learn to wait a bit longer. Good virtues for younger readers. I fear that long term, many companies risk sullying themselves when trying to help make products more accessible to all.

Magnus, I think most use some form of spring only system. Sightron are the only maker that I am aware of who uses mechanical tracking. There may be others - I simply do not know. I do not have all of the facts. I was for example told that Leupold use a form of locked tracking in their Mark series scopes. But alas, I have no evidence of this and so I have to assume that it is potentially misleading info.

All that I do know for sure, is that nearly all brands apart from Sightron use some from of coil or flat spring only - or with some form of armature which offers little in the way of extra support.

If you work from the bottom of your elevation through to center, reliance on a spring only system is normally fine, up to about 375 H&H recoil level. The higher you work your turret and or the higher the recoil (e.g. 10lb .375 RUM upwards), the less one can rely on flat or coil springs only.

I have made several broad sweeping statements here, gross generalizations. Do keep this in mind.
19 Mar 2020
@ 10:44 am (GMT)

Magnus Vassbotn

Re: A word on Sightron tracking vs other optics
Very interesting, thanks alot for the thourough answer.

The only scope I have ever used for really extended range (around 1500 meters) and extreme elevation dialing was a S&B PM2, and it worked well. But that was a 300 wm weighing 18 pounds total, so not more recoil than a normal 6,5x55 or 308.

My buddies end I have used a few Zeiss V8s and lots of Zeiss Victorys, but with the normal ASV turret they are confined to one rotation, so that may help eliminate problems with lack of spring tension. A bit of a hampering design, that one rotation zero stop patent, but it still gives 6,5 mil in the victorys and 9,5 mil in the V8s I believe, so they work well for moderate long range (7-900 meters with most standard cartridges), which is as far as I'm currently interested in practicing. Never had issues with POI at this degree of dialing.

However, after I stumbled onto this site, the interest in accuracy and long range has been somewhat renewed, so there is a good chance my next scope will be more of a long range scope (S3 or S-tac).

Cheers

19 Mar 2020
@ 10:47 pm (GMT)

Ben Law

Re: A word on Sightron tracking vs other optics
so on other scopes the turret is like a bolt, screw it up or down and the spring keeps the erector tube against the turret screws.

how do the sightrons mechanical system work? is the tube fixed to the turret screw somehow?

by the way an s3 4-20x50 would be great in moa2 reticle or a new 1moa reticle.
20 Mar 2020
@ 06:13 am (GMT)

JOHN HAYS

Re: A word on Sightron tracking vs other optics

BTW,

My current understanding is that in the 1” Sightron tubes the distinction between the SII and the SII “Big Sky” is that the latter has the better Zact-7 TM 7-Layer lens coatings.

Keep this in mind when shopping used scopes.

Please correct me if I am wrong. Such info may not be easy to come by from Sightron.
20 Mar 2020
@ 07:32 am (GMT)

Nathan Foster

Re: A word on Sightron tracking vs other optics
Hi Ben, hope the below image is clear enough. Left shows conventional optic, right shows the ring that Sightron use.



Just to give an idea of how good the system is, my hunting buddy Kelvin dropped his heavy rig a while ago after taking a fall while out hunting. Both he and the rifle went down hard (carrying a heavy pack). The elevation turret on his SIII was bent by the fall. However the scope is still accurate and is tracking true. Not ideal but its still working. Another one of our flock did the same down south a while ago, the rifle went over a bluff, fell a short distance, scope bent and beat up - but still accurate.
20 Mar 2020
@ 08:19 am (GMT)

Nathan Foster

Re: A word on Sightron tracking vs other optics
Just to further clarify, it is the ball type joint that keeps the rifle accurate all the way through to its outer settings under recoil. Although the image above is exaggerated, readers should be able to understand that the moment the erector is taken off center in a conventional scope, the contact area is heavily reduced, resulting in a reduction in control.
20 Mar 2020
@ 12:27 pm (GMT)

Scott Struif

Re: A word on Sightron tracking vs other optics
Yeah, Nathan, I get it, from your penultimate comment. It whizzed over my head the first time. But when I re-read it, I understand.
20 Mar 2020
@ 05:06 pm (GMT)

Nathan Foster

Re: A word on Sightron tracking vs other optics
If its OK with you guys, I would like to add some further statements to this. The above (original) image from Sightron is I believe actually wrong. I was mulling this over earlier today while waiting for my barrels to cool between groups. I fear that by making assumptions based on an incorrect drawing, I have put you guys wrong. Lately I have been going though a self de-bullshitting process, being quite hard on myself as we set about writing my next book. I am glad I have been going through this but calling ones self to question is never easy.

In any case, I checked the old drawings of the assembly through to new because I suspected (after posting for Ben), that the original (higher res than shown above) drawing was incorrect and that the system could not work. It doesn't, physics dictate that this cannot be achieved.

The ring forms a ball which stays centered with the tube. But the ring does not sit in a groove or divot (it can't as far as I can see). Instead, as the most recent drawing shows correctly, it merely sits on the flat of the erector. Sightron state that the turret screw also has unique qualities to aid control. Of this I know nothing. This was my mistake upon seeing the recessed fit on the original drawing, making an assumption based on misinfo without investigating further.

The ball staying true to the flat appears to be what keeps the system working so well, maintaining the POI where other brands fail, even those with additional guiding armatures.This is how the scope maintains excellent control. Otherwise, the entire system really is just held in place by an opposing spring. Sightron have a right to claim this system as being the most optimal form of control, but its not as controlled as the original drawing showed, not that I can see.

I have checked this over as best as I can. I can talk to the guys at Sightron again soon for more info if readers want this pursued further, but would rather wait till financial sectors are more settled.
20 Mar 2020
@ 08:00 pm (GMT)

Ben Law

Re: A word on Sightron tracking vs other optics
thanks Nathan.

surprising how much of a beating some scopes can take.

be interesting to hear what the guys at sightron have to say about the design.
20 Mar 2020
@ 08:29 pm (GMT)

Magnus Vassbotn

Re: A word on Sightron tracking vs other optics
That robustness is very impressive. I know at least a couple of guys who could benefit greatly from that. Will bring it up next time they're in the market.

And thanks for the detailed description of the scopes innards. Was curious about that too. It's strange that this and similar concepts are not more common. Doesn't seem that complicated/ expensive to develope and manufacture. Maybe it's because springs in most cases work just fine, unless you really start pushing the limits of the design, and look for errors. So for the vast majority of hunters/ shooters it's never an issue, and the manufacturers can live with the small percentage of problems. But again, if they just took the time to develope a similar system, it can't be much more expensive to produce. Especially in the big picture.
21 Mar 2020
@ 04:23 am (GMT)

Scott Struif

Re: A word on Sightron tracking vs other optics
Yes, Nathan. Thanks for your time. The inner workings, while fascinating, are academic. The important thing is it works, based on your field experience, and that of your buddies. Get back to The Door!
21 Mar 2020
@ 10:22 am (GMT)

Nathan Foster

Re: A word on Sightron tracking vs other optics
I took some footage this morning of the S-TAC and SIII reticle in low light. Unfortunately, the cameras did not work so well. The image was clearer than is shown via the camera. The camera should be considered worst case.
21 Mar 2020
@ 12:00 pm (GMT)

Nathan Foster

Re: A word on Sightron tracking vs other optics
Try that again:

https://youtu.be/_eZn7m8vfVo
27 Jan 2021
@ 01:34 pm (GMT)

Laurence Walkinshaw

Re: A word on Sightron tracking vs other optics
Hi team, I'm keen to hear how you are getting on with this scope after some time, especially on the heavy kickers (thinking of your mule Nathan) Ive been interested in Sightron for a while, mostly thanks to NF's recommendations but I also follow Doc Watson on the ole face tube who also rates them and puts them to excellent effect culling goats at long range, think he's based in Kapiti? Anyway, it's destined to go on top of a Bergara 300wm. Originally i were after the Siii, I got my wires crossed however and instead have an STAC coming in to my local shop to have a look at (it's about the 4th scope the poor guy has got in for me to have a look at - sightron are hard to come by at the moment- and I don't have the heart yet to ask if he can get an Siii as well...) I'm not gonna lie, there are some reservations about it being a tier down from their Siii on a proper long range rifle and after exhausting all things sightron on the web I'm still at abit of a loss. Any thoughts or musings would greatly appreciated.

Ta
28 Jan 2021
@ 07:28 pm (GMT)

Hamish Gibbs

Re: A word on Sightron tracking vs other optics
Hi Laurence where are you based? Perhaps there is somebody close to you that would be obliging enough to let you sight their sightron optics?
07 Feb 2021
@ 11:55 pm (GMT)

Laurence Walkinshaw

Re: A word on Sightron tracking vs other optics
Hi Hamish, I'm based in Northland but soon to be moving to Canterbury. The bloke in the store did end up getting anSiii for me to have a look through (He honestly went above and beyond, nothing was too much trouble) It was great to have the opportunity to look through both. Both probably on par or near as dammit as far as clarity of the glass goes, however, the Siii let in a lot more light - you could see a lot of the tube through the Tac which gave the impression of the scope being darker with a narrower field of view. The Tac had a heavier reticule which I liked - and illuminated. I'm not gonna lie, I was for a time caught up with the idea of an illuminated reticule but I ended up going with the Siii in the end and I'm pleased with it. Clean and simple with no additional gimmicks or needless bells or whistles to distract or fail. In breaking the barrel in I was taking my shooting sessions right to the last of the shooting light and managing - It will do the job just fine.
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