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Hunting the sub in "sub-MOA"
Posted by b1rdd0g on September 10, 2014 at 4:06 amGreetings! This is my first post, here. I've owned two Tikka T3 rifles, now, both the SS Lite model. The first, a .270 Win., was a remarkable shooter, easily achieving sub-MOA, consistently. I recently decided to eschew hunting game for punching paper, and so I decided to swap for a .308 Win. I sold my .270. I've had my new .308 to the range twice, now. On my first trip, I did the break-in routine of running the bore snake through every few shots. All the while, I was trying to get consistent 3-shot groups. I used the same Zeiss Conquest 3-9×40 scope (on both rifles). I fired from the bench using my Steady Rest shooting platform as well as from sandbags. Unfortunately, I was unable to consistently achieve sub-MOA groups. In fact, most of my groups were >1 MOA, with only 1 group out of 10 <1 MOA (about 3/4"). Some of the groups were >2 MOA–very disappointing!!
While I waited for my new rifle to arrive, I collected ammo of several different makes and loads in .308 Win. So from my very first range trip, I was able to sample the performance of 4 different brands and loads:
- Winchester SuperX 150 gr PowerPoint (my .270 Tikka loved this stuff!)
- Remington 150 gr Core Lokt soft point
- Norma Match 168 gr HPBT
- Nosler Match 175 gr Sierra Match King HPBT
I am an Appleseed IIT, so I've got a pretty good grasp of marksmanship fundamentals. Nonetheless, I know I've still got a thing or two to learn about the shooting disciplines. One takeaway from my first range session was that, at 9X magnification, I can already begin to recognize the effect of a my pulse on the steadiness of my reticle against the target. So I left the range thinking that this shooter just didn't perform very well.
I studied the wisdom of the Google regarding controlled breathing and heart-rate, and then I went back to the range determined to “do better”. Alas, I got almost identical results with each ammo on my second range trip. The only good thing about it is that I learned that the Nosler match ammo with the heavier 175 gr HPBT easily outperforms all the others, which are statistically all tied for second place. Oh, and I really did manage to slow my heart-rate and settle the reticle better, too.
Nevertheless, I still find myself “sub hunting”. I have done a modicum of research on the leading causes of accuracy issues with the Tikka T3 rifles, and I've turned up two items that might be culpable:
- The two “nubbins” inside the stock at 5 and 7 o'clock just past the chamber bulge.
- Insufficient tightening of the two Torx action screws.
As for the first item, I noticed significant fretting where the two nubbins have rubbed small shiny spots in the otherwise matte finish of the barrel (after only ~65 rounds). There seems to be mixed opinions about the purpose of those nubbins and whether or not there will be any significant improvement (or detriment) if they are removed. I am leaning towards removal. I would like to hear opinions from other Tikka shooters who have also removed those two pressure points.
As for the action screw torque, I broke loose the front screw, and then when I went to break the rear screw, to my great surprise, I found that it was already loose! I suspect that might have a significant negative impact on consistency!! I will definitely be torquing those to the Beretta recommended 35 in-lbs, before my next range trip.
Finally, please add any additional tips for reducing group size that you may have learned with your Tikkas.
TorontoAlex replied 8 years, 11 months ago 13 Members · 46 Replies -
46 Replies
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1 Bullseye
You've taken the major step by tightening the action screws.
Remove the nubs, it will settle down your groups. Before I did, I was getting the 2 and one syndrome, or the 3 and 5, if you know what I mean.
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66 Bullseyes
I removed the nubs in my T3 Varmint and haven't noticed any ill effects.
When you tighten the action screws, make sure the action is seated into the recoil lug. Then slightly snug up the front screw, followed by snugging up the rear screw. Then go back to the front screw and apply the recommended torque, followed by torqueing the rear screw.
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1 Bullseye
As the OP in this thread, I now have some updates. I got my rifle back from CDI Precision. They installed new bottom metal so that I can use the 5 and 10 round AI mags. And I got my new scope, a Vortex Viper PST FFP 4-16×50. (Previously had a Zeiss Conquest 3-9×40 with duplex reticle) Of the two potential accuracy issues discussed previously: the “nubbins” on the fore stock and the loose action screws, I decided to address the latter, first, while leaving the former as I received it from the factory. I reasoned that I should only change one factor at a time, else I might forever wonder which (if either) factor was the more important.
I am unhappy to report that, on the whole, my results are unchanged. Granted, I am just learning the ins and outs of this new scope, but I haven't tried to do anything dramatic, yet–I'm still just shooting 3 shot groups bench supported at 100 yards. Most of my 3 shot groups are in the 1-1.25″ range. I did have one at about 5/8″ and another about 3/4″. What is galling, though, is that I truly believe that I should be able to produce hole-on-hole groups with this rifle/scope combination. And several times, I had two shots one atop the other followed by an “outlier”.
I have now removed the “nubbins” so that the barrel is completely free floated. After my next range visit, I'll update this post, again, with my results. If this modification doesn't resolve my issue, I'm uncertain what else I could do.
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1 Bullseye
I've found replacing the crappy factory recoil lug with a steel one takes ~1/4″ off the groups on my Tikkas. My 308 also really likes the 208 amax, but I live at 4750 feet. Your elevation may limit how heavy you can go.
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1 Bullseye
Personally I've never had any factory ammo shot consistent sub 1 moa groups. My .308 T3 shoots 1/2 moa groups with home loads but that took a while to get the load developed.
Might be worth loading your own -
1 Bullseye
Personally I've never had any factory ammo shot consistent sub 1 moa groups. My .308 T3 shoots 1/2 moa groups with home loads but that took a while to get the load developed.
Might be worth loading your ownMy expectations are somewhat skewed, I suppose. My first Tikka T3 was identical to this one except the caliber which was .270 Win. With that rifle, I could consistently shoot same-ragged-hole groups with Winchester Super X Power Point ammo from Walmart. I just sold that rifle, too 😉 I suppose that I might have to get started loading my own recipes, someday, but I'm just not ready to start that learning curve, yet. It will be a couple weeks before I get another chance to visit the range, but when I do, I'll see what effect, if any, removing the twin nubbins from the fore stock might have. I also plan to acquire some additional factory loads with 175 gr bullets of various types. On my first trip out with this rifle, I tended to get tighter groups with the only ammo I have loaded with that heavier bullet. (Nosler Match Grade 175 gr SMK HPBT)
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1 Bullseye
Well, I went to the range today. I had removed the “nubbins” from the inside of the factory synthetic stock in hopes that those might have been introducing some unhealthy harmonics. I can now slide a dollar bill as far as midway up the chamber bulge in the barrel. But, alas, it seemed to have made no discernible difference.
My average 3-shot group size is still just in excess of 1 MOA. I had 2 groups out of 7 that were <1 MOA, one about 5/8" and another about 7/8". I had a couple poor groups of >=1.5 MOA. This is disappointing, to say the least. After I put this .308 away, I got out my AR and shot comparable groups using a tactical CQB scope with a 4.5 MOA aiming dot!
I did one thing differently, today. On my previous trips, I was shooting at 8X magnification. On this trip, I used the full 16X magnification for every group that I shot. I also found that this enabled me to more easily find “sharp” focus with the side focus knob, though I still cannot get the target in sharp focus at any point of my parallax adjustment. Based on this fact alone, I am going to send the scope back to Vortex for evaluation.
I did notice something else that puzzles me. I did a lot of dry fires between live round groups, today. And I frequently noticed the reticle “jump” at the falling of the firing pin. The only explanation I've ever thought possible for this was shooter error. But after today, I'm not so sure! I'm not dragging wood. I'm pulling straight to the rear with the pad of my finger. I'm trapping the trigger to the rear after the break. And I'm following through by “calling my shot”. (I am an Appleseed IIT, and that's how we roll!) I've done this countless times in sling supported prone position, standing, and kneeling. And I've never seen anything like this. It is as if the image of the reticle superimposed on the target is suddenly replaced with another image wherein the two are no longer superimposed. The image seems to change instantaneously. That's the best way I know how to explain it. And it didn't happen on every dry press, but I'd guess 1-in-3 would be about what I recall. I'd appreciate any suggestions as to what might cause this to happen. Keep in mind that I'm shooting either off sand bags and a rear bag or else from my rifle rest, so even with “bad form”, I shouldn't be able to move the rifle in such a dramatic way. But there is something going on there. I've just got to figure it out!
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1 Bullseye
I'm leaning in the direction of scope issue now… It'll be interesting to see what vortex finds when they get it back
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1 Bullseye
It will likely be a few more weeks till I get my scope back from Vortex and have an opportunity to provide another range report. But in the mean time, I ran across an article in American Hunter (NRA periodical November 2014) on the Weatherby Mark V Ultra Lightweight RC (i.e. Range Certified) in .270 Wby. Mag. In this product review, the author propounded upon the good the bad and the indifferent about this rifle, as usual. What I thought most telling, though, was the data he shared on the accuracy results. With 3 different types of ammo, he shot average 3-shot groups of 1.45″, 1.06″, and 0.99″ at 100 yards from sandbags. He mentions his best group 0.66″ and worst of 1.91″, also. This just about perfectly describes my current experience with this Tikka T3 in .308 Win.
I had to chuckle for two reasons: this rifle retails (MSRP $2400) for about 4X what I paid for my Tikka T3 Lite SS, and while he is getting paid to do this, he doesn't seem to be shooting any better than I am!
So this made me wonder: do I have any right to hold any higher expectations for my 100 yard groups? I'm positive I was able to shoot a same hole group at 100 yards with my previous Tikka T3 in .270 Win. And I'm pretty sure that I've read others on this forum who would claim to be able to do much better than this on a regular basis. So what say you? Would you buy that rifle?
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1 Bullseye
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.
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21 Bullseyes
I am happy for you that the weaver gives you better clarity. I have not used one so cannot comment on its glass or eye relief.
I did own a Vortex Viper PST 4-16 FFP Illuminated and traded it for similar Vortex 6-24 FFP Illuminated and much prefer the 6-24.
If you want the lower power minimum, you might want to check the optic evaluations found on YouTube under the poster “tiborasaurus Rex” (or close to that). He gives a good profile of many tactical scopes based on price and quality. I bought an SWF 10×42 super sniper that fully lives up to his review.
I love my vortex @24x for load testing.
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).
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1 Bullseye
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.
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1 Bullseye
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.
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1 Bullseye
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?
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1 Bullseye
I hate muzzle brakes. I've had the same experience as you at the range and it takes all the pleasure out of shooting. can't handle the recoil? get a smaller caliber!
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