savage 110ba 338 lapua = 2+moa rifle???

[bodywerks]

I invite anyone in Tucson that is familiar with this rifle to show me that it is just me! Because I would much rather know that I just need more practice with a higher recoil rifle. This is a serious offer...
I am an honest MOA shooter with my factory-barrelled savage fcp-k in 308 on an average day, and have shot a few 1/2 MOA groups with it and one sub-1/4moa group with it with my own handloads on good days. But yes, I am still, for all intents and purposes a novice shooter, so maybe its just me. But after about 200 rounds of various loads using retumbo and us869 powder, hornady and lapua brass, Berger and sierra 300gr bullets, and cci and Remington magnum primers - all in various different combinations and charge weights, I'm starting to think there's something going on with the rifle.
To date, the best group measured about 1.5", but average groups are between 2 and 3 inches using retumbo. US869 has been even worse, averaging 4 inches!!!
So what do you think? Do I write this rifle off as a scatter gun, or do I need to spend more money on more different powders and bullets? I already know that this particular rifle prefers the heavier bullets and I bought this rifle to tease the mile mark so lighter bullets wouldn't work for me anyway - neither would a powder that can't keep muzzle velocity up. But at this point I am willing to try anything that others have proven in this rifle.

[LG]

Bodywerks,

Have you checked to see if the scope mounts/rings and action screws are tight and secure? Something might have loosened up with recoil. There's also the possibility that the scope is not holding zero.

On the rifle itself, how does the muzzle crown look? Any nicks or burrs?

[bgc]

I had a time with my 300WM during break-in and after I messed with the Accustock. After following the Accustock tightening procedure, outlined on this site it settled back down. FWIW my gun did not like the hotter loads. (either did my ears, "substantial muzzle blast", Its insane I cant imagine the 338)

[Carvera]

What distances are you shooting at?

That round is definitely a long range thumper, and I would assume that those heavy bullets would take a few hundred yards in order to stabilize.

Just had this talk with a great friend yesterday on this very topic.

[Nefarioud]

Do you have reliable access to longer distances? I've never even fired mine at under 300. Like someone mentioned it seems the bigger bullets take some distance to settle in. I've actually never shot mine for groups but I have gone 10 for 10 on an 8.5" steel gong at 700 yards more than once and average 8 for 10 on a 20 inch gong at 1500 yards using around 101 grains of US869 (I forget the exact number and don't have my notebook with me).

I'd suggest before you write it off take it someplace and let it stretch it's legs. I know it's common belief is that groups don't get better as distance increases, but if the bullets are still in nutation, they won't print like you'd expect.

[dcloco]

I am with Carvera on this.

Don't even bother looking at the groups at 100 yards. Start at 200,.....and preferably 300 yards.

[Balljoint]

Man at the gun club has a 338 at 100 yards 1.5 all day but at 600 yards still 1.5 5 shot groups can't figure it out

[dcloco]

Man at the gun club has a 338 at 100 yards 1.5 all day but at 600 yards still 1.5 5 shot groups can't figure it out


Not sure if I have enough mathematically or physics phonics in my vocabulary to explain this, but have experienced this in a couple of calibers.

Believe, due to the momentum, size of projectile, and weight of projectile, the bullet is not found it's "moment" to begin stabilization. Not flying sideways, but in a circular pattern.

As the flight downrange progresses, the bullet sheds a little speed and rotation starts to slow as well.

I wonder if a word for this has not already been coined, outside of bullet ballistics. Moment of spinning/flying object stabilization? Call it the spinfly stability factor. :)

[placek59]

adding a little bit to what dcloco has said:
I have always heard of that being called, when the bullet "goes to sleep", or stabilizes. The best way I can explain it is to compare it to throwing a football. You want a nice tight spiral to be as accurate as possible, once you throw the ball and it's a "duck" or not a perfect spiral there is nothing you can do about it. However, with bullets, I have had it explained to me that they will self stabilize and turn into a tight spiral after a little while. That is how it was explained to me, and I hope it may make sense to you too. Soooo, you may just need to stretch it's legs a little before giving up on it. Now I am not positive about this, but it is a way to explain the 1.5" @ 100 and the 1.5" at 600.

[earl39]

One might also look at the vibration in the barrel being transmitted to the bullet much the way an arrow flexes when it leaves the bowstring. After a distance or amount of time it will stop flexing and fly true. This could be an exaggerated way of showing what happens before the bullet goes to sleep. That would explain trying to hit a node in barrel harmonics so as to impart as little wobble as possible to the bullet.

Gary

[Nefarioud]

adding a little bit to what dcloco has said:
I have always heard of that being called, when the bullet "goes to sleep", or stabilizes. The best way I can explain it is to compare it to throwing a football. You want a nice tight spiral to be as accurate as possible, once you throw the ball and it's a "duck" or not a perfect spiral there is nothing you can do about it. However, with bullets, I have had it explained to me that they will self stabilize and turn into a tight spiral after a little while. That is how it was explained to me, and I hope it may make sense to you too. Soooo, you may just need to stretch it's legs a little before giving up on it. Now I am not positive about this, but it is a way to explain the 1.5" @ 100 and the 1.5" at 600.


Yes, the term is Nutation. There's a pretty good explanation in the book Understanding Firearms Ballistics by Robert A Rinker. The bullet wobbles about a bit in both pitch and yaw until it gets stable. The mass of the bullet has an influence on how long it takes. Some think it's because of variables in angle of departure, the above mentioned barrel vibrations, or slight inconsistencies in pressure as it passes the crown.

The Lapua isn't really a bench cartridge and the term accurate is relative. 1.5 at 600 is freakin' amazing. I would consider that it's role, as it was designed, is to hit people and things HARD really far away. My experience is that the 110BA does this quite well.

[macon]

did you break in the barell? have you tried fed 215 primers? have you tried h1000? i used the lapua 250 scenars and 300 gr. smk but my lapua would only shoot fed primers and really liked h1000 powder

[Eric in NC]

Yes, the term is Nutation. There's a pretty good explanation in the book Understanding Firearms Ballistics by Robert A Rinker. The bullet wobbles about a bit in both pitch and yaw until it gets stable. The mass of the bullet has an influence on how long it takes. Some think it's because of variables in angle of departure, the above mentioned barrel vibrations, or slight inconsistencies in pressure as it passes the crown.



+1 - seems against reason, "impossible" etc. when initially thinking about it, but have seen it myself with BPCR cartridges throwing big (long) bullets. 540 grainers out of 45-90's and 430 grainers out of 40-70's etc. will often group the same (in inches) at 100 and 300 yards.

[Jamie]

I have found it to be a common happening with heavy for caliber bullets. Even had 300 yard groups SMALLER than 100 yard groups. Truth be told, with a .338 Lapua, i wouldn't even look at accuracy until I hit 600 yards, and that would just be gee-whiz. I'd set my loads for 1500 yard groups.

Yes, what load you use can vary greatly by the yardage being shot. Quite often the best 100 yard group is not going to be the best 300 yard group. And the best 300 yard is not always the best at 600 yards. Get the distance you want to shoot at and work your loads for that distance.

[hawk-i]

Hi to all, this talk of bullet nutation is interesting and also new to me until I read the posts on this subject...doing a little research the following helped to confirmed this phenomenon...it's a little lengthy but interesting. (but still some reviews I have read on the BA 110 say 1/2 MOA @ 100 yds) so I'd say there has to be a reason causing it....just my 2 cents worth


4.6 Ballistic Coefficient Dependence on Coning Motion

The correct technical term for “coning motion” is gyroscopic precession. We call this motion “coning motion” because this name, although not precisely correct in a technical sense, creates a visual image which clearly portrays the motion. Figure 4.6-1 illustrates coning motion. An interesting analogy to the motion of the bullet is the motion of a football thrown by a quarterback. When the bullet is perfectly stabilized in flight, the spin axis of the bullet is almost perfectly tangent to the trajectory, that is, almost perfectly aligned with the velocity vector of the bullet as it flies. We have seen this in football games when the quarterback throws a “perfect” pass. receiver. This same concept of perfect stabilization applies to the bullet, as illustrated in Figure 4.6-1(a) .

Sometimes in a football game we see a quarterback throw a pass which TV commentators described as “wobbly”, which corresponds to the situation shown in Figure 4.6-1 (b) . When a football “wobbles”, the nations the “wobbling” bullet will shoot lower than it would if it were perfectly stabilized.

A third type of angular motion is possible with both a football and a bullet. This motion is called nutation or “nodding”. In thon does not damp out quickly, the bullet, or the football, will tumble in flight.

In the case of a bullet, precessional motion (or coning) and nutational motion may result from “tipoff” force thround the geometrical axis. The coning motion which results from “tipoff” forceersist throughout the entire flight of the bullet.

It turns out that coning motions are worse for long, slender, heavy bullets than for lighter and shorter bullets. The reason is that the long, heavy bullets have a large separation distance between the center of mass and center of pressure of the bullet. However, a bullet which undergoes coning motion, and even a little nodding motion at the beginning of its flight, is not unstable, that is, it will not tumble as it flies. The spinning motion of the bullet, which is caused by the rifling in the gun barrel, gyroscopically stabilizes the bullet in flight, although the stabilization is not perfect when the bullet cones. The cone angle is small always, and the nutation angle starts out very small and dies out very quickly.

Coning motion has very important effects on the measurement of ballistic coefficient of the bullet. If the bullet is coning, it presents an effective area which is larger than the true cross sectional area of the bullet, and the drag pressure of the air acts on this larger area to produce a larger drag force on the bullet. This can be seen in Figure 4.6-1 . When the bullet is tipped with respect to the trajectory, as shown in Figure 4.6-1 (b) , it clearly presents a larger area for drag to act upon than it does in Figure 4.6-1 (a) . This is because drag acts backward along the direction of the bullet’s velocity vector. The result is an increase in the drag force experieere perfectly stabilized.

How do we know this for sure? Let’s look at some measured data. Figure 4.6-2 shows results of two sets of measurements of the ballistic coefficient of the Sierra 910 grain Hollow Point Boat Tail MatchKing bullet. The first set of measurements involved 14 rounds fired, with the ballistic coefficient of each round measured by the three screen method, that is by measuring muzzle velocity and time of flight between the muzzle chronograph and a third screen downrange 50 yards from the first screen of the chronograph. The data are plotted and the statistics are given on the right side of Figure 4.6-2 . The second set of measurements involved 16 rounds fired, with the ballistic coefficient measured by the four screen method, that is with initial velocity measured by a muzzle chronograph, and the final velocity measured by a chronograph set up 250 yards downrange from the muzzle chronograph. The four screen method had to be used for the longer distance because the time of flight to 250 yards exceeded the capacity of the electronic counter used to measure time of flight. The data are plotted and the statistics are given on the left side of Figure 4.6-2 .

The average values of the measured ballistic coefficient differ by almost 10 percent and the average values of the velocities differ by only 135 fps. From the spreads in the velocities of the rounds shown in the figure, and it is obvious that there is no strong trend in the value of ballistic coefficient with velocity for either set of measurements. Therefore, we attribute the difference in average values of ballistic coefficient to the fact that the bullets were coning, and the coning did not damp out over the 50 yard range, while it damped out well over the 250 yard range.

To support this observation further, look at Figure 4.6-3 which shows the variation of measured ballistic coefficient of the .30 caliber 190 grain Hollow Point Boat Tail MatchKing bullet as a function of twist rate in the test barrel. Six barrels were used in this test, with twist rates varying from one turn in 14 inches to one turn in 8 inches. Fifteen rounds were fired through each barrel at velocities near 2350 fps. The ballistic coefficient for each round fired is plotted in the figure. The figure also lists the average value of ballistic coefficient for the 15 rounds, together with the standard deviation and extreme spread, for each of the six twist rates used. Note that one barrel chambered a .300 Winchester Magnum cartridge, while the other five barrels chambered the .308 Winchester cartridge.

We know from common knowledge that if the twist rate of a barrel is too slow, long and heavy bullets will not be well stabilized. They do not tumble in flight, but the holes in paper targets are elliptical rather than round, indicating that the bullets are coning. Figure 4.6-3 shows what happens to the measured ballistic coefficient in such cases. For the faster twist rates, out through one turn in 11 inches in the case of the 190 grain HPBT MatchKing bullet in this test, the average values of the ballistic coefficients differ very little, and the statistical spreads are tight. When a twist rate of one turn in 12 inches was reached, the average value of measured ballistic coefficient dropped by more than 2 percent, and the spread of the measurements increased substantially. At a twist rate of one turn in 14 inches, the average ballistic coefficient decreased by more than 30 percent, and the spread increased dramatically. We emphasize that none of the test bullets tumbled in flight; all were gyroscopically stabilized, though marginally for the slowest twist rate.

This test dramatically illustrates the effect of coning motion on measured ballistic coefficient. Figure 4.6-4 shows the same test conducted on the .22 caliber 69 grain Hollow Point Boat Tail MatchKing bullet, with the same obvious results. The conclusion is inescapable that coning motion reduces the average measured ballistic coefficient and increases the statistical spread of the measured values.

Another observation we have made is that with long, slender Spitzer and Spitzer Boat Tail bullets the average measured ballistic coefficient at high muzzle velocities is significantly lower than at intermediate velocities, and the statistical spread of the measured values often (but not always) is significantly greater. We believe that this is caused by greater coning motion imparted to each fired bullet at high muzzle velocities compared to intermediate muzzle velocities. We suspect that this results from the larger amounts of powder gases exiting from the bore, resulting from the larger powder charges necessary to obtain higher velocities. This effect is shown for the .375 caliber 250 grain Spitzer Boat Tail bullet in Figure 4.6-5 . The measured ballistic coefficient has an upward trend between the measurements at 1585 and 2240 fps, and then it drops dramatically between 2240 and 2785 fps. We believe this dramatic drop at higher velocities results from greater coning motion at the higher velocities. Note that in this particular case the statistical spread in the measurements at the high velocity level did not increase dramatically. This means that the bullets are coning consistently from round to round.

What have we learned from this experience with coning motions? We now know that ballistic coefficients must be measured downrange from the muzzle at a distance sufficient for the coning motion to have died out. Coning motions are caused by side forces applied to each bullet as it exits the muzzle, but in all but very severe cases the coning motion will damp out within about 100 yards downrange from the muzzle. Consequently, we have set up Sierra’s underground test range to measure ballistic coehe time of flight screen is positioned about 150 yards downrange from the firing point.

[mytwo60]

Bullet dispersion: http://www.the-long-family.com/bullet_dispersions.htm

I have the same problem but not quite as bad as 4" groups at 100yds. ;D

I have 2 rifles:

One average in the .3s and the other in the .6s. At 300yds, the .3s rifle opens up to 2.5" and the .6s rifle shoots 1.6" groups for 10 shots.

After getting off my lazy azz I went and chronod both rifle loads and turns out the .6s rifle ES and SD is WAY better than the .3s which explains the better groups at 300yds.

So if you really want to know what the deal is with your rifle/loads then shoot it thru a chrono.

[earl39]

mytwo60 just reminded me of a neighbors savage 308. this was a used rifle he traded a winch for and he could not get it to group with any load he tried. he ran his loads thru a chrony and found he would have 2 or 3 out of every 10 showing 1000fps (yes that is one thousand) slower than the rest and none were consistant. i told him it was his chrony so he came over and shot across mine. same thing. i said brass issue so we sized some of my once fired m118lr brass and once again the same problem. then we neck sized only and like magic the problem went away. i can not explain what was going on. we used midrange loads and what should have been hot loads but the necksizing only fixed the problem.

Gary

[lostart]

The easiest way to picture the issue is to think of it as a top....wobbles at first then stabilizes then as it looses speed, starts to wobble again.

[bodywerks]

Bodywerks,

Have you checked to see if the scope mounts/rings and action screws are tight and secure? Something might have loosened up with recoil. There's also the possibility that the scope is not holding zero.

On the rifle itself, how does the muzzle crown look? Any nicks or burrs?

I'm familiar with some of the problems this rifle has had with the scope rail being loose and what not. I have an egw base on mine and I have checked the screws 4 times so far and the screws were tight. I doubt my nightforce was not holding zero, and I used that scope on my other rifle without issue. I have since switched to a Weaver tactical for the last 25 or so rounds but it is also holding zero fine on my other rifles.

[bodywerks]

What distances are you shooting at?

That round is definitely a long range thumper, and I would assume that those heavy bullets would take a few hundred yards in order to stabilize.

Just had this talk with a great friend yesterday on this very topic.

while you may be right, it doesn't explain how others with this rifle are getting sub-moa groups at 100 yards. And I don't buy the whole groups getting tighter with distance. If I shot these rounds through paper at 300 yards after first going through paper at 100, there is no way the groups at 300 will be smaller than they were at 100.