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I was referring to the reason behind the horizontal stringing...

The above target shows the the 2nd shooting of this load. Shots were run over a chrony both times.

BP...

I heard you on that. I have an O-ring under the forearm.

BP...

If I could see a target at 200 yards and hit it with iron sights I wouldn't need to have all these high dollar scopes. To many birthdays I guess.

BP...

I've had my best luck with rebedding 99 forends by checking to see if the rear end of the forend is binding on the front of the action. In a surprising number of rifles there's considerable pressure there, and if it's on one side in particular it can cause horizontal stringing. I just relieve any pressure with a fine file rather than epoxy-bed. This essentially free-floats the barrel AND forend.

I've owned a bunch of 99's and generally expect scoped pre-million serial numbers to group 3 shots in around an inch at 100, and some have done much better.

I'd also roll your ammo over a piece of glass. If you can see the tip of the bullet "wobble" then the bullet is seated pretty crooked, enough to cause definite fliers.

Forgot to add: The tables in the back of the Nosler manual say the 150 BT @ 2800 should be 3.6" down at 200 if the rifle's zeroed at 100. Your load is dropping twice that.

boilerpig,

Your post is interesting and all, but what I'd really like is to see the obverse side of your avatar. You wouldn't, by chance, have that to share with us, would you?

I hear you regarding too many birthdays. I've got a pretty good collection going on myself, right along with age related failing eyesight.

When you get your 99 sorted out, please make a post as to what the problem was. I am interested as to the cause.

You betcha. Thanks all for the ideas.

BP...

Another thing I've noticed with my 99s, is they seem to like the forearm support to be as far rearward as possible, damn near under the action. My EG model 99s seem to be more fussy than other models. If it doesn't help, it didn't cost you nothing to try.

Also remember that a scope's reticle subtends twice as much area at 200 yards as at 100, making precise aiming more difficult. Scope parallax may also figure into the equation as well. Personally, compared to the group at 125 yards, that 200 yard group doesn't look all that awry. Maybe you could do a little impromptu test of the parallax by fixing the rifle in the rest and moving your eye side to side in the eyebox to get an idea of how parallax might be affecting you at both ranges.

I just skimmed through the replies and didn't notice anyone mention that your bullets may be unstable. If so, they get progressively worse as they go down range. At 100 yds, they hit nearly point on, and given a descent group but as they continue downrange, they become increasingly "wobbly" (technical term), which destroys accuracy.

It also really increases drag so the bullet begins to slow much faster and thus, the bullet has a longer time to drop. Thus the much lower average POI. That seems to be the case in the photo you have shown but it's hard to be sure.

I would suggest a substantially shorter bullet - but check your rifle's crown first. Might be other causal mechanisms too, but those are two easy ones to try.

The too symptoms taken together add up to a ballistic problem. I would further guess that if you shot at clean cardboard (or better clean foam board) you would find the 200 yds holes are larger, more oblong than the 100 yds holes are. That would be the third symptom to look for.

Brent,

The reason I didn't mention bullet instability as a possible cause was that the standard twist in the .300 Savage is 1-10, which is far more than needed to stabilize a 150-grain Ballistic Tip. Sierra twist calculator suggests a 1-14 twist is sufficient, and the Miller Formula (the best I've encountered) says that a 1-10 will provide a stability factor of over 2, and 1.4 is considered plenty.

MD, I do agree that it seems improbable given a standard barrel but perhaps it is a replacement barrel. There are other ways to get bullets to be unstable but they take some effort to make happen. Loading exceedingly cock-eyed cartridges, a poorly throated/chambered barrel, damaging bullets when seating/crimping, etc. might do it. My suggestion to look at the crown is another. MD, you can probably come up with 20 other ways to get a bullet flying cattywumpus as well.

The symptoms you describe are a dead ringer for the problems we so often in BPCR and esp. BPTR where we are always pushing the bullet weight to the limits over excessively long range. Faster twist barrels, shorter bullets, and sometimes more velocity (if possible) generally fixes the problem. But whether this is likely with your M99, I don't know.

I'd sure like to see some close ups of the bullet holes in the cardboard from the 100 and 200 yds targets. If they are less round at 200 yds, then bullet stability IS the problem. Finding the cause of the problem may, however, be problematic.

If I'm able to make it to the ranch this weekend I'll get you some pictures of the backboard. But I seem to remember, they were round. I saw no signs of tumbling.

BP...

If you can shoot new ones - do it on fresh cardboard, preferable with something firm behind it. Look close.

Brent,

Wiht spitzer bullets in smokeless centerfires, bullet stability actually increases with distance.

Bullet instability occurs for two reasons:

1) Air pressure on the front end of the bullet overcomes the center of mass toward the rear of the bullet.

2) The bullet enters the transonic zone between about 1100-1300 fps, which introduces weird forces.

With spitzer bullets fired from smokeless cartridges, bullet stability actually increases until velocity drops enough for the bullet to enter the transonic zone. This is because air pressure on the sharp front end decreases rapidly (with velocity) but spin slows down at a much slower rate.

A .30 caliber 150-grain Ballistic Tip is not only not nearly long enough to be marginally stabilized in a 1-10 twist, but when started at 2800 fps it won't be anywhere near the transonic zone until close to 1000 yards. And even if the barrel is a replacement, I sincerely doubt it would have a 1-14 twist, since they're almost unknown in .30 caliber centerfires--and 1-14 would still be plenty to stabilize the 150 BT.

I copied the photo of the target and blew it up and three of the four bullet holes at 200 yards are perfectly round. The other hole shows a slight opening on the right side that looks like an irregular tear in the cardboard, rather than an oblong shape to the hole.

Yeah, there are reasons other than twist for bullets to be unstable as they leave the muzzle, but if a 150-grain Ballistic Tip from a .300 Savage is stable at 100 yards it will be stable at 200. The same applies to a worn crown. Crooked-seated bullets aren't unstable, they just leave the muzzle with their base at a slightly different angle than straight-seated bullets.

Which is why my money is on a forend bedding problem.

MD, you are probably right. But I don't think so. I do absolutely agree that the twist should be enough to stabilize that bullet. No doubt.

I understand 1 and 2 and yes, they are not a factor here.

I cannot even come close to seeing enough detail in that target to say anything about what bullet holes are perfectly round and which ones are not. It is hard enough when looking at a target up close and in person.f If they are keyholing sure, but then most of the bullets would be missing altogether.

But one thing is for certain - unless the two groups are unique flukes of chance. And that is that accuracy as is rapidly, very rapidly, declining with distance. Those bullets are becoming ever more inaccurate while they are flying and long long after they leave the muzzle and any influence of the forearm bedding etc. If your forearm hypothesis is correct, and the rifle shoots 3MOA at 100 it the forearm can't cause it to shoot 6 MOA at 200 because by the time the bullet reaches the 100 yds line, it has long forgotten the forearm per se. It can only be less accurate if something is happening to the bullet out there in the middle of the range. That leaves just the bullet's intrinsic properties and the environmental conditions such as wind.

If wind conditions etc, do not factor in, then the group size at x00 yards should be reasonably x times the group size at 100 yds. No news to you there, but this is dramatically larger. I would doubt that any environmental variables (e.g., wind) changed sufficiently to cause that increase in group size above this expectation or the OP would have mentioned that.

So, it's got to be intrinsic to the bullet itself. And that means stability, regardless of what the numbers say. I disagree that you can launch a wobbly bullet and expect it to be stably wobbly such that the "cone of fire" or MOA of accuracy would be maintained. It is knuckleballing out there and when it does that it's shedding velocity fast (thus the huge drop from the expected center of the group). And the big increase in MOA group size.

I don't know how the forearm would cause that group to drop like that, nor how it would induce a larger MOA. I just don't see a mechanism. So, I'm sticking with my story - besides, I've been there, done that too many times.

But maybe you are right. Maybe we will find out. It would be interesting to know.

I had a 338 Lapua that would not stabilize one particular 325 grain VLD rebated boatail. When this happens horizontal stringing is the least of your troubles.

This may get me in trouble....but I don't think there is anything wrong with the rifle or the load.A lot of the analysis being made(good suggestions!)are based on two groups,and assume the OP is holding perfectly each and every time(Not dumping on the OP, just being realistic).

Three of the four shots in the 125 yard group are trending "right"( and those three are not strung and the group is pretty good)....this right tendency will be exagerated at greater distances and shows up in the lower group..I bet the horizontal stuff is due to alignment and the forend of that Savage rolling around in the bags and bouncing off the firm bags as he fires.There may also be cant in the scope or the way the OP holds the rifle that we can't see.

As for the lower impact, I think he just has to take it back to 100 and zero so that he's a full 2" high above that white dot.POI should come in at 200 or close to it.I'd also do what another poster suggested and get the forend off the bags back more to the receiver.Might also try a soft towel under there to try to minimize freaky bounces off the rest as the rifle recoils.