[b1rdd0g]

Alex, I had seen this video, previously, but I did watch it, again, tonight. They do provide a useful description and demonstration (e.g. eye, thumb [reticle], and target) of parallax that makes the whole concept easier to grasp. I found the discussion of the magnitude of possible error due to parallax (I had to study the chart [at 6:07] very carefully to grasp what they were showing) very helpful. And isn't really all that bad at hunting ranges and game-sized targets. But for longer distances and for target work, it can contribute to overall inaccuracy.

Thinking about the demo, irrespective of whether the image and the reticle are in focus in the same plane, or not, if the shooter is extremely careful to place the eye in the center of the eyepiece, parallax error can be eliminated, anyway, right? IOW, proper sight alignment! (Step 1 in Appleseed's Firing the Shot)

I found another quote from a forum on SnipersHide that was helpful to consider:

It's important to note, that up-down movement and side-to-side movement of the head should result in you seeing the exact same amount of parallax error(assuming you moved your head the same amount in each direction). If not, that is the optical error in the system and can not be corrected.

To correct image path induced parallax ALWAYS start at infinity and turn down. If you over shoot, you cannot just go back up a little bit, you must start over at infinity.

I had to experiment with this at home, so I got out my SteadyRest and some wedges so that I could essentially make the SteadyRest behave as a gun vise. I have a limited FOV from my upstairs office, so I aimed my (empty!) rifle at a chimney hood about 100-140 yds away. As advised, I started at infinity, and at maximum magnification (15X) and I found that the target was already in the best possible focus (I could see heads on screws) at infinity. Bobbing my eye up-down, I could see parallax. So I dialed it back until I no longer noticed the reticle moving off the target with up-down eye movement. The focus dial was pointing about 150 yds, which is pretty darned close to my estimated distance! At this point, I moved my eye side-to-side. And to my great surprise, I witnessed very little parallax. During my last range session, it seemed very noticeable. Though still, there was some noticeable parallax with side-to-side motion, even with my gun in a vise. Which led me to consider whether this falls into the category of what the fellow from SnipersHide mentioned above about “optical error in the system”. Also in the video, the guy from Leupold mentioned something about some movement due to “curvature of the lens” that could not be avoided. It sounds like this is what I have been noticing at the range with my particular scope. Note also that most of what I am noticing is occurring only at the outer limits of my exit pupil, anyway.

This leads me to question whether my step #1 to adjusting the scope–adjusting the focus of the reticle using the eyepiece–has been done correctly. I think this is where the condition of my eyesight is playing a detrimental role in this whole debacle. I have been finding step #1 really really hard to accomplish with much confidence. I have become extremely presbyopic (far sighted). In fact, I have made several marks on my eyepiece where I think my reticle is in proper focus. Like The Highlander, “there can be only one!”. Perhaps if I can manage to get step #1 done right, maybe I'll begin to notice that the point in my side-focus adjustment that brings the image into sharp focus will begin to approximate more closely the point at which parallax seems to vanish. I'll keep working at it until I figger it out!

[b1rdd0g]

Hi, Alex! I see you already found my thread! (And I just now posted in yours and referred you to mine.)
Based on my discoveries since my last range trip, I have made some additional adjustments on my rifle.

First, I felt the eye relief wasn't optimal, so I removed and remounted my scope to bring it about 3/8″ closer to my eye. Now I get a good, crisp, black border around my FOV at all but the very lowest magnification (and that only for the standing position, where my cheek weld is slightly different than prone/bench). Additionally, I needed to keep my Southwest Precision Kydex cheek rest from slipping, so I did some post-installation engineering changes to pin it in place. (If anyone is interested in details, I can post procedures and pictures.)

Today's range trip was instructive. First, I continue to shrink my overall average group size for 3-shot groups (~0.7″). I know! I posted previously that I averaged about 5/8″ (0.625″), but on that trip I fired only 3 types of ammo, all match grade stuff. On this trip, I mixed in several different loads, some of which has not, historically, been among my best performers. So I believe that my trend of improvement is still intact.

And speaking of different ammo types, I noticed something else interesting over my last two range trips. I had bought some Winchester SuperX 150 gr Power Point and Remington 150 gr Core-Lokt SP ammo–your typical Walmart deer loads–to try in this gun, and these things just don't perform in this rifle! Moreover, it is interesting that, while all my match ammo began shooting dramatically better after the installation of my muzzle brake, these two deer loads now shoot worse still! The Winchester shoots just comically bad (2 1/8″ to 4 5/8″)! I can't begin to explain why “the best got better and the worst got worse”, but that's my story, and I'm stickin' to it!

And then there's that parallax thing. I'm still puzzling over that. Before I shot any groups, at all, I went back and addressed my reticle focus, first. Then I adjusted my objective to get a crisp image of my target (at highest magnification). And then I bobbed my head up and down to check for parallax and made some final adjustments to eliminate parallax. Even so, moving my head left-to-right causes significant shift in sight picture, regardless what else I might do. With my scope, it is significant. I'd estimate +/- 1.5″ from one side of the exit pupil to the other. Even more dramatic was the scope that my buddy was shooting. (I recall that it was a Nikon scope, but I didn't get the exact Model.) His scope exhibited the same behavior, namely no apparent parallax with up-down movement but literally from one side of the target to the other (about 8″) when moving my head side-to-side across the exit pupil. This phenomenon does NOT make sense, to me! If the reticle and the target are in the same focal plane, it shouldn't matter which direction (vertical or lateral) the eye moves; it shouldn't change the apparent alignment of the reticle with the target! But it does! I think I'm going to post this on additional fora to see if I can find an optics wizard who can offer an explanation for this observation.

[b1rdd0g]

Alex, you might find it interesting to follow my own post as I have been trying to get consistent sub-MOA performance from my new Tikka T3 Lite SS in .308. You can read about my discoveries along my own journey here: https://tikkashooters.com/public_html/general-discussion/hunting-the-sub-in-'sub-moa'/msg3517/#msg3517

That said, I may have had an epiphany, today, that may offer a possible contributing factor to explain  your counter-intuitive observations. You never mentioned what kind of scope/reticle/magnification/target, etc. that you were using. But as I have finally gotten consistently into the Sub-MOA Club at 100 yds over my last few range trips, I have begun to notice that my groups shot at 8X are at least as good if not better than my groups at 15X. Intuition tells me that I should expect to get a more precise hold with higher magnification (just as you would expect larger groups at greater distances, everything else being equal). But my range data, too, is (just slightly) contrary to my intuition.

My scope is a Weaver Tactical 3-15x50mm. It has a FFP mil-dot reticle with mil adjustments. Nice scope! I eventually intend to stretch this rifle to longer distances, so I intend to tinker with doing range estimation with my mil-dot reticle, at some point. The FFP reticle is ideal for that. That is what makes this a good “Tactical” scope. But the FFP reticle looks kinda fat at 15X. It really makes it more difficult–not easier–to judge a precise hold (i.e. sight picture) shot after shot. That's why target shooters are perfectly happy with (cheaper) SFP reticles. So what I am suggesting is that, depending on your scope (and equally important, the style of target you are aiming at), you may be getting a more precise hold as you shoot farther and farther, thus compensating for the increased distance. It's a hypothesis, anyway!

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Larken, it sounds as though you are describing what I've heard called the “artillery hold”. Perhaps that technique is worth a try on a future range trip.

I appreciate the encouragement. I guess I came off sounding kinda negative? I sure didn't mean to. I'm actually enjoying the learning process! I am incrementally exposing faults with the gun and/or faults with the shooter, and every time I go to the range, I intend to learn something new. As in most things that I undertake, I am very detailed and painfully slow. I always have been that way. But I do persist, and I certainly will in this case, as well. I'm having too much fun not to! Thanks for your advice and encouragement!

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Yes, Ericbc7/airfoil, I was pleasantly surprised to achieve the improved results with the addition of the muzzle brake.

It is clear, though, that I'm not quite “done” with learning/tweaking my rifle, yet. (or with tweaking the rifleman 😉 I was doing some dry practice in the Appleseed manner, and it became apparent to me that my “check weld” was something more akin to a “jaw weld”. I had been using a strap-on padded cheek rest, but it clearly was insufficient to consistently place my eye into the optical center of my scope (Weaver Tactical 3-15x50mm). So I have installed a Southwest Precision Kydex adjustable check rest to get the height that I require. It, no doubt, improves my consistency in sight alignment, but on my first range trip with it, I noticed (too late!) that it had been slipping as I was shooting. The hollow Tikka stock seems to just flex all the more as I tighten the screws on the cheek rest. I'm pondering some additional post-installation modifications to get it to stay put.

One additional thing that I confirmed at my last range trip is that my eye is positioned too far back to achieve the correct sight alignment (or eye relief) such that I eliminate all scope shadow.  So I took my scope down and reinstalled it, yesterday. Hopefully I'll get my desired sight alignment without having to stretch my neck forward, as much.

One additional finer point that I am still struggling to master is parallax. As much as I think I understand the concepts, I am still struggling to eliminate (perceived?) parallax. I went back to Google University, last night, and I watched the several Youtube videos that attempt to address this topic. One takeaway is that to properly assess parallax, it is important to be able to keep the rifle absolutely motionless while moving your eye up-down or side-to-side. I really need to get my SteadyRest out, again, to help me better make that assessment. But what is really puzzling, to me, is that the reticle doesn't seem to move with up-down eye movement, but it moves dramatically with side-to-side eye movement. In fact, it seems to move as much as +/- 1.5″ (at 100 yds) from one side of the ocular to the other. My understanding of the physics says that shouldn't be so. So I will focus (pun not intended 😉 on that topic some more on my next range trip.

[b1rdd0g]

Eureka!!! I've found it! I would never have guessed that adding a muzzle brake would have improved accuracy. Reduce recoil, sure, but improve accuracy, too? It did both!

OK, so the first 3-shot group of the day was way off target, but a nice 0.5″ group. The second group was a 0.625″ group at the exact same POI shift. I dialed it back to zero and shot 13 more 3-shot groups by the end of my range trip. My average group size was about 5/8″, and my worst group of the day was just 1.25″ (and that one was a called flyer, as I broke position)! That is most definitely sub-MOA, my friends! Kudos to Witt Machine!
http://wittmachine.co/index.php?main_page=product_info&products_id=180

Now, in thinking about how the muzzle brake is having such a beneficial effect on precision, I have a couple ideas. I'd like to hear your ideas and/or experience, as well. The first notion is that it somehow reduces barrel whip by adding mass out on the end of the barrel. I suppose it has to change the harmonics of the barrel, somehow, right? Another idea has to do with the fact that it does reduce muzzle jump. (It still jumps too much on the bench for me to see the impact at 100 yd., but it does jump less than before.) I would have thought the bullet was long out of the barrel before the gun leapt off the bench from recoil, but maybe it imparts some movement before the bullet is ballistic? And finally, there is the psychosomatic theory–I expect it to shoot softer so I bucked/flinched less. Let me hear your stories.

I think I'm about ready to begin my learning curve beyond 100 yd, now.

[b1rdd0g]

OK, I finally got over the flu long enough to get out to the range and test the new recoil lug. To sum it up, I'd have to say that I can't tell any appreciable difference. I've got my Witt Machine clamp-on muzzle brake installed, now. I'll make another range trip to test that before making any further adjustments to try and improve my accuracy.

I went back through all my old targets and started capturing my range data into a spreadsheet for analysis of my shooting, after the fact. My average group size has improved from about 1.36″ on my first range trip to about 1.1″ on my last visit. I've also noticed that I have fewer “bad” groups (>=1.5″) and more “good” groups (<=0.625") as time goes on, even though it is hard to see a great deal of improvement in my average group size from one range visit to the next. I've ordered some Hornady Match and SuperPerformance Match ammo to test on my next range trip. In the mean time, I'll be trying to think of another improvement I might be able to make in my shooting technique.

[b1rdd0g]

Update on this thread. I've identified a new suspect in my quest for consistent, sub-MOA precision: the aluminum recoil lug. I've got to say that, while I've read that this can make a significant difference, I have been slow to believe it could really make a difference. I mean, aluminum is pretty permanent metal, right? But I've ordered a steel replacement from Mountain Tactical, and I'm going to give it a try!

Here is what caused me to take the plunge and order this, seemingly insignificant upgrade:
[img]http://tinyurl.com/nkdamty[/img]
Notice the trapezoidal crease around the top of the lug. I can't actually measure any noticeable difference in thickness of the lug with my calipers, but I can run my fingernail into that crease! I'm kinda at a loss to explain the mode of metal deformation that I'm seeing there. But it is clear that there is some unwanted plasticity, there. So this will be my next range test, provided I get a chance to head out to the range sometime soon.

And then queued up right behind this upgrade, I have ordered a Witt Machine clamp-on muzzle brake:
http://wittmachine.co/index.php?main_page=product_info&products_id=180
I'm not particularly expecting an accuracy improvement from the muzzle brake, but I expect it might make shooting the rifle a bit more fun. I'm hoping to be able to maintain my sight picture after the shot breaks so that I can “call my shots”. But one thing at a time–I'll get to that in a future post.

[b1rdd0g]

Thanks for the input, y'all. Yea, I've been next to folks with muzzle brakes on the public range, and it isn't particularly pleasant. And equally unfortunate is that the public range is, for now, my only convenient option for a place to shoot. That is why I've been wondering whether I could get the same reduction in muzzle jump by using an internally installed mercury recoil reducer in the butt stock. I'm sure the dynamics are different, regardless, since the operating principle behind the two devices are different. I would value anyone's advice who has had experience with both devices.

Robert_P–wow! 2500 rounds of .308 in 18 mos!!! I'll never be able to shoot that much if I live to be 85! That would also mean you spent ~$2500 in the same space of time. I expect if I were able to shoot that much, I'd probably start getting pretty good at this! I guess that is one of the perks of living in Montana!

[b1rdd0g]

mikgarus, I'm not sure if you were trying to condescend to me (OP) or to airfoil??? BTW, my rifle is a .308. If I understand what you are stating, you seem to be among those who find the back blast associated with muzzle brakes annoying. Is that right? Keep in mind that we were discussing how to reduce “muzzle jump”. If you can share some constructive advice on reducing muzzle jump, please do share with this…um…princess.

Larkin, I missed the gist of your post, entirely. Can you clarify? Was it directed only to mikgarus or was it intended to add to the thread discussion?

airfoil, I sincerely appreciate your obvious intention to be helpful. I am seriously considering a bolt-on muzzle brake, since my barrel is not threaded, at all. I've read somewhere that removing the barrel on a Tikka T3 is difficult, even for the experienced gunsmith. But I'm not in any particular hurry about it, so I've got time to weigh advice and think about it a bit before dropping any more money into this rifle.

As for loading the bipod, I had literally no experience with a bipod prior to my last range visit. But I did learn about the concept of “loading the bipod” from Google University. I was shooting off a carpet covered wooden top bench, so there was a little bit of something for the bipod legs to grab hold of. I can't say with certainty that I loaded the bipod exactly the same way (or amount) each time, though–it's completely new to me.

I have a rear bag from midwayusa.com, but I don't find it particularly easy to use. It seems as though they filled it with especially large beads (or whatever). I may see if I can make a homemade squeeze bag and see if I like it better.

[b1rdd0g]

A muzzle brake cuts the recoil down considerably on my .308…still bounces (benched, with bipod and bag), but if I hold right, it comes back to point of aim…almost.

I have anticipated a response like this. I haven't any experience with either, but I am wondering whether a muzzle brake or a mercury recoil reducer might produce better results. There are are the obvious detractions for the muzzle brake, namely the increased noise for the shooter and the increased annoyance for the neighbors on the firing line. I was at the range once where the lady adjacent to me was firing a .308 with a ginormous muzzle brake attached. Each shot sent a blast of gases jetting across my bench. Not very neighborly at the local public range! Anybody had experience with the mercury recoil reducers? Any suggestions for a muzzle brake for a Tikka T3?

[b1rdd0g]

Optics aside, if your bench technique is lacking, then all your data is suspect.

Sit your rifle on a bench with bags such that you don't need any muscle or input to maintain hold, even if you look away or only touch the rifle with your shoulder and trigger finger.  Not exactly true but close enough depending on caliber and rifle. (I wouldn't reccomend this “free” technique for harder recoiling calibers).

Eric, I appreciate your response. No doubt, I need to improve my bench technique. I am an Appleseed IIT3, and actually fairly new to riflery, in general. In all, I have tried about 3 different ways to steady my rifle on the bench:

• Steady Rest shooting rest. “Shooters Ridge” I think, but some type of Lead Sled knockoff from China
• Range provided wooden front rest & sand bag and rear squeeze bag (Midwayusa.com)
• Bipod and rear squeeze bag

I can't really say that I've noticed much difference from one approach to the next as far as how tight my groups are. I'm looking back over my numbers, and I can see that I shot better in the morning off the steady rest. In the afternoon, I switched to my bipod–the first time I've ever shot off of one. I know from Youtube U that I'm supposed to load the bipod each shot, and I tried to do that. But about half of my groups in the afternoon were sloppy bad, so I guess I've got some work to do on the bipod technique. Still, my best group of the day was in the afternoon, as well, so I speculate that my mental focus was probably slipping some as I fatigued. Also, I found that I was having a hard time keeping the reticle sharp as the light began to fade, so that played a role, as well. Oh, yea, and another reason my afternoon numbers took a dive is that I tried some groupings with non-match ammo, and both of those groups were, predictably, pretty bad. As you probably suspect, I too believe my rifle is capable of much better than I've managed to get out of her, to date.

Oh, and one more thing. From Appleseed and other sources, I know that follow through is important. However, shooting this .308 seems to make that pretty much impossible! Regardless which approach I use to steady the rifle, once it goes bang, I find that I am no longer looking at anything of consequence in the scope. I have to recover my sight picture each and every shot. My nephew was just relating to me how a friend of his, a renowned marksman with lots of different weapons, would take the shot, and keeping his eye on the scope without blinking, watch the impact down range. I don't see any way for that to happen with my current knowledge and/or technique.

[b1rdd0g]

This is repeat posting of this, in case anybody is still watching this thread and not my other thread (Re: Learning the Vortex Viper PST FFP 4-16×50 rifle scope)

OK, I finally got to visit the range today with my new Weaver Tactical 3-15×50 scope. The first observation I can report is that the glass definitely provides “superior image resolution” as compared to the previous Vortex 4-16×50 scope. I easily obtained zero in about 2 shots from the 25 using the bore sighting method, so that's a positive, too. And with the “superior” glass, I now find that I can, in fact, dial the parallax adjustment knob until the target image is sharp and crisp. So my major complaint with the previous scope is resolved.

And now to touch some negative and “mixed reviews” items. I find the “eye box” is really fussy on this scope compared to the Vortex scope. I suppose it might be that the exit pupil is smaller (though that sort of thing is usually published)? I think I may eventually miss the fact that I don't have a zero stop on the Weaver scope. The Vortex shim stop is arguably kinda kludgy, but at least they have one. Even with a 20 MOA base, I find that I have about 2.5 turns (12 mils?) below my zero. Like other Weaver users, the pop-up locking turrets sometimes don't want to pop back down without a little bit of fiddling. I prefer the Vortex reticle design over the Weaver, though it still has to be an improvement over the original mil-dot reticle the military developed. One nice touch is that the center of the cross hairs is left open, making it easier to tell when the reticle is precisely centered over the POA, especially if the target has an open center, as mine did today. I did the “shoot the box” drill with this scope, and at first blush, I thought it passed with flying colors. I immediately found that the elevation clicks were spot on (0.36″/.1 mil). However, when I got home and measured the windage, I found that I got somewhere between 0.31 and 0.34 inches/.1 mil, or as much as 14% error. I suppose something like that would deeply disturb the purist. But in my view, any windage adjustments are going to be guesstimates to begin with, which will no doubt introduce errors that will dwarf this one in magnitude. And none of it matters if I've got a good spotter to walk me in. (Maybe a bit wishful thinking that last bit… 😉 Still, I find it really cool to shoot 4 3-shot groups at a single POA resulting in 4 targets with nicely placed, tight groups in each.

Finally, I would have to say that, compared to my previous range trips, my groups have gotten better. In my previous trips with the Vortex scope, my mean 3-shot group size was probably 1-1/8″. On this trip, my mean group size was about 3/4″ with my best at 1/2″ and 3 others were about 5/8″. My worst were, well, they were shooter errors! So there is nothing to learn about my rifle from those!

One more new piece of information is that I found another ammo that my rifle likes pretty well. Silver State Armory 175 gr. HPBT Match ammo cost me about $22/20 at Cabelas. Most of the other match ammo that I was shooting cost considerably more and didn't perform any better. One thing is for sure, though, unlike my last one in .270, this Tikka T3 in .308 don't much like the Winchester PowerPoint and Remington Core-Lokt “deer” rounds very much! Those were the worst groups of the day, hands down.

[b1rdd0g]

OK, I finally got to visit the range today with my new Weaver Tactical 3-15×50 scope. The first observation I can report is that the glass definitely provides “superior image resolution” as compared to the previous Vortex 4-16×50 scope. I easily obtained zero in about 2 shots from the 25 using the bore sighting method, so that's a positive, too. And with the “superior” glass, I now find that I can, in fact, dial the parallax adjustment knob until the target image is sharp and crisp. So my major complaint with the previous scope is resolved.

And now to touch some negative and “mixed reviews” items. I find the “eye box” is really fussy on this scope compared to the Vortex scope. I suppose it might be that the exit pupil is smaller (though that sort of thing is usually published)? I think I may eventually miss the fact that I don't have a zero stop on the Weaver scope. The Vortex shim stop is arguably kinda kludgy, but at least they have one. Even with a 20 MOA base, I find that I have about 2.5 turns (12 mils?) below my zero. Like other Weaver users, the pop-up locking turrets sometimes don't want to pop back down without a little bit of fiddling. I prefer the Vortex reticle design over the Weaver, though it still has to be an improvement over the original mil-dot reticle the military developed. One nice touch is that the center of the cross hairs is left open, making it easier to tell when the reticle is precisely centered over the POA, especially if the target has an open center, as mine did today. I did the “shoot the box” drill with this scope, and at first blush, I thought it passed with flying colors. I immediately found that the elevation clicks were spot on (0.36″/.1 mil). However, when I got home and measured the windage, I found that I got somewhere between 0.31 and 0.34 inches/.1 mil, or as much as 14% error. I suppose something like that would deeply disturb the purist. But in my view, any windage adjustments are going to be guesstimates to begin with, which will no doubt introduce errors that will dwarf this one in magnitude. And none of it matters if I've got a good spotter to walk me in. (Maybe a bit wishful thinking that last bit… 😉 Still, I find it really cool to shoot 4 3-shot groups at a single POA resulting in 4 targets with nicely placed, tight groups in each.

Finally, I would have to say that, compared to my previous range trips, my groups have gotten better. In my previous trips with the Vortex scope, my mean 3-shot group size was probably 1-1/8″. On this trip, my mean group size was about 3/4″ with my best at 1/2″ and 3 others were about 5/8″. My worst were, well, they were shooter errors! So there is nothing to learn about my rifle from those!

One more new piece of information is that I found another ammo that my rifle likes pretty well. Silver State Armory 175 gr. HPBT Match ammo cost me about $22/20 at Cabelas. Most of the other match ammo that I was shooting cost considerably more and didn't perform any better. One thing is for sure, though, unlike my last one in .270, this Tikka T3 in .308 don't much like the Winchester PowerPoint and Remington Core-Lokt “deer” rounds very much! Those were the worst groups of the day, hands down.

[b1rdd0g]

Well, I thought I would put this thread to bed for good. I did send the scope back to Vortex for service. Long story short, while it cost me nothing (but time), it came back to me no better than it was before. After describing the issue in detail to their service personnel, their best recommendation was to try either their 2-10 or 6-24×50 models, both of which have “superior image resolution” compared to the 4-16×50. It seems that they have some familiarity with this issue. In fact, I found, quite too late, that the Vortex Viper PST 4-16×50 has something of a reputation for “inferior glass”.
http://www.opticstalk.com/vortex-viper-pst-vs-weaver-tactical-opinions_topic28963.html
And there are other similar threads. To their credit, Vortex has offered me a refund on their scope. So I've purchased a Weaver Tactical 3-15×50. Hopefully, I will find, as apparently many others have, that the Weaver glass is superior. This is my first experience with a long range AO scope, which I purchased primarily for learning the long range rifle craft. And I have indeed learnt a thing or two!