Bimodal bullet pattern from Savage 110 HS 338 Lapua

[joeb33050]

Average, largest group/smallest group
with 5, 5 shot groups, the largest will average 1.91 times the size of the smallest
number 2 3 4 5 6 7 8 9 10
of groups shot shot shot shot shot shot shot shot shot
shot groups groups groups groups groups groups groups groups groups
2 1.84 1.53 1.42 1.36 1.32 1.30 1.28 1.26 1.25
3 2.59 1.92 1.70 1.59 1.52 1.48 1.44 1.42 1.39
4 3.33 2.24 1.92 1.77 1.68 1.61 1.57 1.53 1.50
5 4.10 2.52 2.11 1.91 1.80 1.72 1.66 1.62 1.58
6 4.93 2.77 2.27 2.04 1.90 1.81 1.75 1.69 1.65
7 5.82 3.01 2.42 2.15 1.99 1.89 1.82 1.76 1.71
8 6.82 3.24 2.55 2.25 2.07 1.96 1.88 1.81 1.77
9 7.94 3.45 2.67 2.34 2.15 2.02 1.93 1.87 1.81
10 9.23 3.66 2.79 2.42 2.21 2.08 1.98 1.91 1.85

[CharlieNC]

In general accuracy refers to the ability to "hit what you are aiming at " (bullseye when shooting), and precision refers to the uniformity of the result (group size when shooting). Depending on what you are doing (shooting, or producing a product or service) one of these parameters can be more important than the other. In any case as Joe says the more you do and observe the result, the more variable it will appear to be. As a result it can be difficult to determine if the answer you get this time is really different than last time (eg this group vs last group). As a matter of interest shoot 20 shots at a target and then "randomly" pick any 2,3, or 5 (meaning how many you may shoot for a group size) and you may be surprised to see this is what to expect for group-to-group differences in a perfect world. Or shoot 7 3-shot groups at one time and see how much the point of impact changes between groups, esp at greater distances. All this makes it tough for a shooter to determine whether he is making improvements or not for load development, rifle work, etc. Usually after a little load development I continue to find out the weak link is me as a shooter, so I have focused more on technique than anything else (esp with a Savage).

[rotts4u]

What makes this bullet distribution interesting to me is that on all my other rifles that I have shot dating back to the late 80s, there is usually a different pattern (random) bullet distribution. Meaning sometimes the second or third shot is high, left, right, low etc etc. In the case of this particular rifle it is almost always the same. Two shots in a three shot group basically in one hole, then one of the 3 shots will be approx. 1" high.I almost never get holes to the right or left or low of the first shot.

the rifle seems to be capable of delivering 2 shots in a very small one ragged hole, then there is always this 1" high shot then it returns back again to the same hole. Its not just the size of the group that is interesting but the propensity to repeat this same pattern group after group as if something is moving between two spots. I have heard others talk about scope mounts, rings etc etc causing this but as mentioned earlier I checked all of that.

The only thing I have not done is swap the scope for another 30mm tube scope and see if it does the same thing. Most of my scopes are 34mm but I do have a Nightforce 5-22x56 on another rifle I could pull and see if that has any affect or not but that seems remote to assume the scope internals are moving due to the heavy 338 lapua recoil

[DanSavage]

I'd suspect the scope, although I was having the 2 in one hole and flier just like you with a .308 rifle. I ended up switching powder and re-testing seating depths.

You might just want to shoot a 20 shot group over 30 minutes time, and if the group is no bigger than an inch I would be very happy.

[rotts4u]

I have continued to have this bimodal bullet distribution and yesterday after shooting I noticed something as I was cleaning the rifle and I am wondering if this could cause any issues. Where the bolt handle attaches to the bolt on this rifle it attaches via a center allen head screw that holds the bolt handle through its center to the bolt. Mine was loose and it allowed the bolt handle to wiggle around some. Could this loose bolt handle have been effecting how the bolt holds a round in the chamber? I would have thought the locking lugs up front would determine that but I am still scratching my head to figure this out. Since this original posting I have had 2 different scopes on the rifle too and none of that changed anything and of course I checked the mount each time as well.

[Gatr]

I have a 300 win mag that does the same thing. Usually shot number 1 and 3 are touching and shot number 2 is 3/4" high. I don't remember where but I read that this can be caused by a bad factory recoil lug. I pulled it apart and am waiting on a new one.

[Digduggy]

Group of five I always have one flyer high and right... Always...

[rotts4u]

I have a 300 win mag that does the same thing. Usually shot number 1 and 3 are touching and shot number 2 is 3/4" high. I don't remember where but I read that this can be caused by a bad factory recoil lug. I pulled it apart and am waiting on a new one.

I had my recoil lug replaced with a ground flat one during the re-barrel also I bedded the rifle into the stock anyway so that should have taken care of any lug issues right?

[243LPR]

The loose bolt handle could be a possible problem,easy to fix. Hornady makes a nice concentricity for about a hundred bucks,not sure if that cartridge will fit in it though. I got one for xmas last year and check all my loads with it.