7mm-08 sight in issues

So a little break down on the set-up. Have a savage 7mm-08, gun is a mid-2000’s older version of the axis series, has been a very solid reliable gun.

for the last couple of years I have shot the Hornady 139 gr. “whitetail” rounds, cheap and I could find them about everywhere when needed, solid round out to 250 yards, basically fit my needs for coyote hunting the timber here in Wisconsin and Minnesota.

This weekend I put on a buddies scope, maybe a year old(bought a new vortex). Nikon with the bdc reticle. Not so much for the reticle, but it has much narrower cross hairs and it just happens to be a little better quality glass than the simmons that was currently on the gun. Being we had to resight everything we thought this would be a great time to shoot some other rounds and try to get some better grouping at that 250 yd plus range.

I ordered some Nosler 120gr BT. Half dozen shots and we were in business out to 100 yards.
Conditions wise, no wind, sighting into a 100 yards there was a slight upward angle to shooting simply because of the terrain, any yardage past that and I was closer to being level. Shooting out of a lead sled as well.

Dialed into 100yds at roughly 1.5″-2″ high. Slid back to 200yds. dead on up and down, maybe a 2.5″ group with another 5 rounds. Slid back to 250 yards. Bullet began to drop, roughly 5 inches low at this point, still a solid grouping. At this point these were grouping FAR better than the hornadys or any other shell I have put through this gun in the last 5 years. Then out to 300 yds, this is where things went downhill fast. Holding dead on for 3 shots could not make heads or tails where on earth I was hitting. Back to the board, couldn’t find a group of holes in the board to figure out where I was, over a dozen shells later, of course my mind says I am shooting low this entire time, I decide to hold 5″ low and bingo I am somehow 10″ high from my hold. Run back to 250 yds let a couple more out just to make sure I didn’t bump things around, nope, still 5″ low. Shoot a few more rounds holding low and sure enough that’s whats up, easily 10″ high with the next 3 shells, still grouping up consistent. Now I am out of shells.

I did order a couple more boxes of the same round but any ideas what I need to look at? My only guess is the slight angle I was shooting at to get it close to 0 initially is what’s creating the issue?
Or maybe my gun just doesn’t like the round past 250 yards???

Any thoughts from the gallery?

What twist is the barrel?

My initial thoughts are that the lighter 120 grain bullets could be becoming destabilized due to the twist rate of your barrel. When the bullet becomes unstable, they are flying off.

Your twist rate on that rifle IIRC is 1:9. That’s much better suited for bullets in the (approximately) 130 to 160 grain range. Below 130 grain, as you are, the 1:9 twist could be too fast, imparting instability as the velocity drops at greater distances.

Obviously, there are other possibilities, but the easy way to test my twist rate theory is to fire some heavier bullets at the 300-yard distance. If they group better than your 120s, then you’ve honed in on the culprit. Then it’s just a matter of finding out where the break point is by testing different bullet weights.

Since bullet drop seems fairly normal out to 250, my first suspect is that something else is going wrong and it’s not a scope issue. At least that’s my first line of thinking.

One other thought. Is your barrel heating up too much in the process of testing? How fast are you shooting all these rounds and how much time are you allowing for cool down between groups?

Barrel heat does some wacky stuff. Make sure you are firing and pausing at a rate that never allows your barrel to become more than warm to the touch. If it’s uncomfortable to touch the barrel or even worse if the barrel is outright hot, you are overheating the barrel and that will cause accuracy issues.

Grouse

Just from previous years nothing shot worth a darn in that 139 + grains at 300 yds. The few I ran through were what I would consider “cheaper” rounds. Core lokts 140 gr., Hornadys in both 139 gr. and Hornady custom Lite 120 gr. and federal 150 gr. hot cor. None of these were even close to the group I shot over the weekend with the noslers out to 250.

The odd thing when I thought of maybe it was just coming out too fast for my barrel to handle is that it was a consistent group aside being as high as it was.

Heat although certainly possible, shouldn’t have been an issue, I never noticed anything out of the ordinary through handling the gun and whatnot. I went through less than 50 shells in 4 hours of shooting, taking turns between 2 of us shooting, the walk in the snow was getting very old!!!!
Never shot more than say 3 shells in a “series” of shots, sometimes even minutes in-between single shots, screwing with the sled, finding the bullet hit, partner rip of a dozen shots from his AR etc.

Jason Beaulieu wrote:

Just from previous years nothing shot worth a darn in that 139 + grains at 300 yds. The few I ran through were what I would consider “cheaper” rounds. Core lokts 140 gr., Hornadys in both 139 gr. and Hornady custom Lite 120 gr. and federal 150 gr. hot cor. None of these were even close to the group I shot over the weekend with the noslers out to 250.

But beyond 250, did these heavier bullets (130+ grain) group more consistently? That is the question.

How many of the 120 grain bullets did you get “on paper” at 300 before you ran out of ammo? Was it enough to determine if your group size is better or worse than the heavier bullets?

Jason Beaulieu wrote:

The odd thing when I thought of maybe it was just coming out too fast for my barrel to handle is that it was a consistent group aside being as high as it was.

Again, back to how many rounds did you get on paper with the various bullet weights? What you’re looking for is CONSISTENCY here. Whether the bullets are left/right/high/low matters less than if the groups are tight.

A couple of things to try that are cheap and easy.

– Use a torque wrench to make sure the screws that hold the stock to the barrel are both tight and consistently torqued.

– Make sure the barrel is free-floating to the bedding pillars by running a dollar bill between the barrel and stock. The barrel should not touch the stock (thus stopping the dollar bill from passing between the barrel and stock until you hit the first bedding pillar.

I own 2 Axis rifles and the second one I bought had a stock that was slightly warped and touched the barrel right at the tip of the fore. Accuracy DID improve after I eliminated this issue.

– Have you replaced or modified the Axis trigger? This is the really weak point of the Axis and we can’t eliminate the possibility that this could be part of the issue.

Grouse

I would think a 1:9 is plenty fast to stabilize a 120gr 7mm. The reason I asked is I thought at one point Savage used a 1:11.5 twist in some of its rifles chambered in 7mm08.

But beyond 250, did these heavier bullets (130+ grain) group more consistently? That is the question.

No, the hornadys grouped the best but I would be lucky if I could throw 3 shells inside a 5″ circle at 300 yds. consistently.

How many of the 120 grain bullets did you get “on paper” at 300 before you ran out of ammo? Was it enough to determine if your group size is better or worse than the heavier bullets?

Now the 4 shells I shot or held low at 300 all were within say a 4″ circle or less, a grouping at that distance I don’t think I’ve seen with any other round.

Again, back to how many rounds did you get on paper with the various bullet weights? What you’re looking for is CONSISTENCY here. Whether the bullets are left/right/high/low matters less than if the groups are tight.

To give a short answer the 120 noslers gave me the greatest group compared to the hornadys or federals that I have shot at that distance and realistically any distance.

I was thinking until we got to 300 that these shells gave some new life to that gun, can’t think of another round that had shot that well out of this gun.

I have not tried the additional things you listed. I will for sure check the barrel itself and figure out where my trigger pull is at.

Thanks again for the insight Grouse!!!

gixxer01 wrote:

I would think a 1:9 is plenty fast to stabilize a 120gr 7mm. The reason I asked is I thought at one point Savage used a 1:11.5 twist in some of its rifles chambered in 7mm08.

My thinking was that the 1:9 could be all right with 120 grain slug velocities, but I thought it at least merited asking the question.

I didn’t look it up, so I don’t know for sure it’s a 1:9, that’s just a very common twist for 7-08s of many flavors.

If it’s 1:11 or slower there is more likely going to be a twist issue at the 120 grain range, I agree.

Jason, for sure we want to find out the twist rate of your rifle. You most likely need to do it manually because if Gixxer is right, there may have been multiple twist rates so looking up the current model won’t be sure enough.

Do you know how to manually check the twist rate? Essentially, insert a brass cleaning brush on a cleaning rod. Mark the cleaning rod with a dot so you can see easily the rod turning with the rifling. Slowly withdraw the rod exactly 12 inches while counting the rotations. I’m sure there are youtube videos on how to do this.

Grouse

I can handle that.

Will report what I figure out!

Thanks guys!

Gixxer01 Nailed this one!

Barrel is a 1:11.5 twist

Barrel floated fine, available bolt heads I could find are all tight.

Back to the 140’s!

Something still doesn’t add up though. A faster twist (1:9) should stabilize a heavy bullet better whereas a slower twist (1:11.5) should work better for lighter bullets.

The COAL of a 120 and 168 should be the same right? Meaning a 120 has the same jump as does a 168? Assuming same ammo manufacturer.

personally I have a 7mm-08 ruger american. I had big issues with 120 gr bullets in it as well but mine does have a 1:9.5 twist rate. I have been loading for this rifle for a little over a year and the best groupings I have ever had were with 160 grain sierra gameking bullets. It seems like you have figured out your issue anyway already Try some 160 grain bullets if you can find them!

I personally would rule out the custom lite 120 from your test data. The reduced velocity is probably the reason for the inconsistency. If you could compare a 120 with proper charge weight you would probably see more consistent data.

Besides, Hornady pushes the 120 to 2675 and the 139 to 2895. You’ll have better performance with the 139.

I would also note that cheap ammo won’t perform at distance. Stick with the premium ammo for distance. Probably why only your noslers performed at 300.

gixxer01 wrote:

Something still doesn’t add up though. A faster twist (1:9) should stabilize a heavy bullet better whereas a slower twist (1:11.5) should work better for lighter bullets.

The COAL of a 120 and 168 should be the same right? Meaning a 120 has the same jump as does a 168? Assuming same ammo manufacturer.

I agree, since it’s the 1:11.5 barrel, in theory the slower twist should favor the lighter bullets. In the interest of science, I would try another 120 bullet.

COAL can be the same, but that does not determine the “jump” or distance the bullet must travel to meet the rifling. That is determined by the ogive of the bullet relative to the beginning of the rifling of the individual rifle.

In other words, two factory rounds can have the same COAL, but because the ogive of the bullets is in a different place, they will have a different distance that they “jump” before they meet the rifling.

Grouse

Also look at the bullet holes at every distance. They should be perfectly round, and should not have any unusual markings This will tell you two things, one is that the bullet is not wobbling or starting to tumble, also it should show how the projectile is maintaining integrity. Hunting bullets have “thin skins” for rapid expansion upon impacting game. Some bullets will start to fragment in flight which can happen when too fast of a twist is matched with the wrong bullet. Match bullets, where ability to expand is not a desired trait, have thicker jackets hopefully giving them truer flight.

I was once playing around with some way to heavy and long bullets for my relativly slow twist in my 22-250. At 100 yards they grouped nicely…even though they were going through sideways, LOL

Can’t say I noticed anything!

Made things simple again, back to 140’s, I know they can shoot!