Range Report Unusual ballistic problems.

[LapuaBob]

I have been having some vary strange ballistic occurrences with one of my favorite loads. At 100 yds i get 4 of 5 shots in one hole, not a raged hole, a .40 cal. Hole. If I do my job. At 800 yds I have sub MOA accuracy. After 1k yds everything goes to hell. The bullets start to string vertically as much as + or - 1 full mil. That's 2 mils of I don't know. The rounds also always land on the vertical hair so they are flying with some accuracy. I think that an accuracy problem this big would show up at the closer ranges. Any advise or idea of what is happening would be appreciated. This recipe has a lot of potential and I would like to use it for ELR hunting because it will carry a lot of energy way out there but i cannot trust it passed 800 yds. Inside 800 I can confidently go for rabbits.

300gr Sierra match king
88gr Retumbo.
COAL 3.68
Remington 9.5 m primer
Lapua brass.
2710 adv MV with 15fps extreme spread.

Shot from a Savage 111LRH .338 Lapua Magnum.

Thank you.

 

[40xs]

Without knowing what size target you are shooting at and how far off the ground the target is and how much beyond 1k you are shooting, it sounds almost as if your rounds are striking the turf and skipping up above your sight line. Just saying!!

 

[bigbear_98]

Could it be mirage?

Also, I have had vertical stringing when the rear of my rifle wasn't supported well. I had let the butt kinda "float" on the bag, not supporting it 100% and got similar results to yours.

 

[LRShooter101]

Running down the list:
Ballistics
Muzzle Velocity / Transonic Stability - not going to be an issue, bullet is above 1,600 fps at 1,000 yards

Gyroscopic Stability Factor (SG) - not going to be an issue, calculated factor is 2.51, which is well above the recommended 1.5

Bullet Condition - only possible explanation that I can come up with, is that the bullet is getting engraved hard going down the barrel, and this change in the jacket makeup/aerodynamics is causing it to climb/deviate as it gets further out / velocity drops off. I have seen something similar, though the deviation was not just high/vertical, it opened up the group size in all directions.


Optics
Adjustments - assuming that you are getting your initial shots on the target as dialed, then unless the scope is slipping/failing under repeated recoil, then this is not an issue. If slipping/failing due to repeated recoil was an issue, you should also see it at other distance, so probably not an issue.

Cant - I would assume that you have a cant/level indicator and are making sure you are shooting level? Error from cant will become more pronounced with distance, but it will usually move your bullet off the center line, not just vertical.

Mirage - this can cause issues, in theory, the more rounds you fire, the worse the mirage from the barrel gets. Not sure if you are using a barrel mirage band/shade? Not sure if you have noticeable mirage in your sight picture, especially with it getting worse as you shoot? This could cause a problem at close range, but it may not be as noticeable/pronounced as it would be at longer ranges.

Aiming Point - with distance, your aiming point can become less defined if you do not have the magnification power to keep up and a fine reticle design to give you a very defined aiming point. You may think that you are aiming at the exact point every time, but in reality you are not. Based on your technique/sight picture, you may be inducing an aiming error in the vertical plane.


Rifle
Barrel Heating - possible as you shoot and the barrel heats that it is walking/tracking vertical. It may not be as noticeable with closer range shots, but it my become very obvious with longer range shots?


Laundry list that I can come up with off the top of my head, some possible candidates to look at, but nothing that is jumping out at me.

 

[LapuaBob]

I'm going to lean on the mirage theory, I should have seen it. You guys are fantastic thank you. And thanks a ton to LRShooter101 for taking the time to remind me to stop over thinking things and look at one thing at a time.

I would still like to blame Sierra but... Oh well.

 

[Aimsmall55]

You tried a different bullet yet ?? I like lrshooter101's idea about the jacketing being off but I tend to think there would be some horizontal dispersion to go along with that. Before I went crazy ( got to be frustrating ) I'd load up some Berger otms and try them out. They are easy to make shoot and the bc is ridiculous.

 

[LapuaBob]

Yes, I stepped up and bought the Lapua 300s... Just in time for this powder shortage. I don't and have not had any Retumbo for a long time. I did just get some RE-33. Its advertised to be capable of similar velocity's (as was Magpro, RE 22, and IMR7828). I have a ladder sitting on the other side of the room teasing me. Going out in a few days and will report.

I hope it works. I bought a lot of RE-33.

Are those Berger's harder than the Sierras? Softer? My Savage was one of the ones with the tight chamber, Retumbo was the only one that would give me the speed without the pressure.

 

[Aimsmall55]

Yes, I stepped up and bought the Lapua 300s... Just in time for this powder shortage. I don't and have not had any Retumbo for a long time. I did just get some RE-33. Its advertised to be capable of similar velocity's (as was Magpro, RE 22, and IMR7828). I have a ladder sitting on the other side of the room teasing me. Going out in a few days and will report.

I hope it works. I bought a lot of RE-33.

Are those Berger's harder than the Sierras? Softer? My Savage was one of the ones with the tight chamber, Retumbo was the only one that would give me the speed without the pressure.

I would have to say the jackets on the target, tactical, and hybrid bergers are harder than sierras smk's. The hunting bullets has a thinner jacket for sure. Don't hold me to that on the target bullets from Berger but I'm pretty sure they are harder.

 

[LapuaBob]

I figured it out. I'm so thrilled. For two reasons. It wasn't the powder or the bullet, and I can fix it. It happens with the Lapua bullets to. I loaded the Lapua 300s with 94.6gr of RE-33 and got similar velocities (a little bit more) and great consistency. I ran the numbers and was soon pulling first shot hits at 1000.

I then took this load to my favorite ELR spot and had the same high-low deviation. After throwing a good old fashioned tantrum. I started thinking and found the answer.

Operator Error.

When I shoot off the edge of a mesa I loose a lot of recoil control. I am horizontal but the rifle is pointed down at the target.

Anyone have any ideas on how to correct it? There is a large Bull Elk that needs to die in November.

 

[Nukes]

Running down the list:
Ballistics
Muzzle Velocity / Transonic Stability - not going to be an issue, bullet is above 1,600 fps at 1,000 yards

Gyroscopic Stability Factor (SG) - not going to be an issue, calculated factor is 2.51, which is well above the recommended 1.5

Bullet Condition - only possible explanation that I can come up with, is that the bullet is getting engraved hard going down the barrel, and this change in the jacket makeup/aerodynamics is causing it to climb/deviate as it gets further out / velocity drops off. I have seen something similar, though the deviation was not just high/vertical, it opened up the group size in all directions.


Optics
Adjustments - assuming that you are getting your initial shots on the target as dialed, then unless the scope is slipping/failing under repeated recoil, then this is not an issue. If slipping/failing due to repeated recoil was an issue, you should also see it at other distance, so probably not an issue.

Cant - I would assume that you have a cant/level indicator and are making sure you are shooting level? Error from cant will become more pronounced with distance, but it will usually move your bullet off the center line, not just vertical.

Mirage - this can cause issues, in theory, the more rounds you fire, the worse the mirage from the barrel gets. Not sure if you are using a barrel mirage band/shade? Not sure if you have noticeable mirage in your sight picture, especially with it getting worse as you shoot? This could cause a problem at close range, but it may not be as noticeable/pronounced as it would be at longer ranges.

Aiming Point - with distance, your aiming point can become less defined if you do not have the magnification power to keep up and a fine reticle design to give you a very defined aiming point. You may think that you are aiming at the exact point every time, but in reality you are not. Based on your technique/sight picture, you may be inducing an aiming error in the vertical plane.


Rifle
Barrel Heating - possible as you shoot and the barrel heats that it is walking/tracking vertical. It may not be as noticeable with closer range shots, but it my become very obvious with longer range shots?


Laundry list that I can come up with off the top of my head, some possible candidates to look at, but nothing that is jumping out at me.

Changing headwind/tailwind component (including updrafts over undulating terrain?) over the string of fire?

 

[bax]

So .... if you go to a 1k range and shoot, you get 1st shot hits. When you go to your ELR spot, you no longer get 1k hits, right?

I cannot speak the to recoil control issue -- I can see loss of accuracy but only vertical? That doesn't compute.

I like the "wind blowing up over the edge of the mesa" giving you vertical. Take the recoil control out of the picture, take a board and rig it up to help you control recoil -- put in a couple of lathe pieces to hold the bipod legs, add some lathe to hold the rear bag, lay on the board so that you get the same recoil as normal, just a different angle. Or, if you can shoot from the same "top of the mesa" position but in a different direction so that you get normal recoil but you still get that wind in the face. If you get vertical with a horizontal shot then it is the wind. Even a little wind near the muzzle will have a big effect out at 1k and beyond.

Could that work?

 

[LapuaBob]

It has happened at a few of my "ELR" spots. After looking through my logs the times it happens is at three of those spots. I had only just put it together. That's just the only thing I can think of that they have in common. I spend a lot of time on those spots. ( a lot of wasted ammo)(I hate wasting ammo!!!)

I have a couple other places and have pulled first shot hits every ware from 700yds to 1763yds (My best). I have missed a lot more but I usually figure out why. But the others had no apparent pattern before we started digging.

It couldn't be wind on the unexplained vertical deviation. Some of these shots didn't have a full mil of horizontal wind effect. Any more ideas?

Thanks to all of you for your time.