Berger .338 300 grain EH - ballistic coefficient

[Timber338]

was wondering if anybody has proven out the ballistic coefficient of the Berger .338 300 grain EH. The accurate load I have dialed in with my 338 RUM is running an average velocity of 2725 with a Magnetospeed V3.

After the first 3 shot group the bullets impacted about 4.5" low at 1000 yards ... So I lowered my G7 BC from .417 down to .400. Shot again with the new drops and it pulled the bullets right in where I wanted them.

I know Berger bc's are accurate and my barrel might very well impart a lower BC onto the bullet... But wondering if anybody else has info to pass along on this. Thanks.

 

[bigngreen]

I would be looking at turret click value and velocity before making BC adjustments and then I would want at least two more data points before tuning to help identify the value you need to tune.

 

[Plinker147]

I feel bullet companies know a lot more Than me about the BC of there bullets. When drop charts don't line up to your real drop I tweak the velocity to make it match then confirm. When you get to tweaking bc it can real mess things up.

There is so much that can affect your shots at 1k. I would shoot some 600 yard groups before you start tweaking too much

 

[DocUSMCRetired]

We know the BCs are accurate, we just updated them. So I have some questions/suggestions:

1. Did you check the MV right before you shot? As you were shooting? Or on another day?

2. What is your barrel twist? We have a calculator that can tell you the decreased BC due to non optimized twist rates and your current location: www.abmediaresources.com/ABToolbox.htm

3. As mentioned before, have you done a Tall Target Test? The before mentioned Toolbox app actually has the math for the Tall Target Test in it, however here is the worksheet on that: http://www.abmediaresources.com/talltarget.pdf

4. What did you use to determine your dope? Did you account for the Vertical aspect of both Coriolis and Aerodynamic Jump?

5. Make sure you measure bore height at the turrets to be the most accurate.

6. If you have a moment, please read this article: http://www.abmediaresources.com/BallisticCalibration.pdf

7. Are you pointing your bullets? If so please read this: http://www.abmediaresources.com/BulletPointing.pdf

We just updated those BCs so we know they are good, something else is going on here.

 

[D.Camilleri]

Timber,

What is the load you are shooting? OAL? I am shooting the 300 Berger in my RUM with 90 grains of H-1000 with a OAL of 3.670 and a magneto speed velocity of 2774. My old velocity I was using was 2830 and when my hits were coming in low, I tweaked my velocity to 2775 and the drops were spot on. I just got the magneto speed and it came in at the same as my adjusted velocity which made me happy. I am very careful to make sure my 100 yard zero is as close to exact on elevation as it can be. Have you tested your scope turret against a tape measure set at 100 yards to see if it tracks accurately?

 

[Timber338]

We know the BCs are accurate, we just updated them. So I have some questions/suggestions:

1. Did you check the MV right before you shot? As you were shooting? Or on another day?

2. What is your barrel twist? We have a calculator that can tell you the decreased BC due to non optimized twist rates and your current location: www.abmediaresources.com/ABToolbox.htm

3. As mentioned before, have you done a Tall Target Test? The before mentioned Toolbox app actually has the math for the Tall Target Test in it, however here is the worksheet on that: http://www.abmediaresources.com/talltarget.pdf

4. What did you use to determine your dope? Did you account for the Vertical aspect of both Coriolis and Aerodynamic Jump?

5. Make sure you measure bore height at the turrets to be the most accurate.

6. If you have a moment, please read this article: http://www.abmediaresources.com/BallisticCalibration.pdf

7. Are you pointing your bullets? If so please read this: http://www.abmediaresources.com/BulletPointing.pdf

We just updated those BCs so we know they are good, something else is going on here.

Hey guys, thanks for the responses... this is exactly what I was looking for... you are all saying the same thing that the BC should be accurate so look elsewhere.

Doc, thanks for the accurate list of things to look for. Below is the answers to your questions. I was using the Shooter App to calculate all of my drops. I am shooting this bullet using 93 grains of RL33 and seated to a .010" jump. Not sure of my COAL to the tip of the bullet because I always use a comparator, but I think it is right around 4 inches.

1: I checked my MV several times in previous days, but not during the day I shot at 1000 yards. The temperature was luckily the same as my most recent Magnetospeed V3 data of 34 degF.

2. I'm shooting a 27" Hart barrel with 1:10 twist. Shooter app calculates the stability wtih the exact temp and pressure at 1.86. I believe stability says I should be getting the max .417 BC.

3. I have thoroughly tested out my scope and it does have error which I do have a correction factor entered into Shooter. My CF = .97087

4. I am using the Shooter app, and I did not account for Coriolis or Aerodynamic jump (is this just spin drift?). Although, I was shooting nearly due north... 8 degrees to be exact. Even if I turn on Coriolis Jump and Spin Drift, Shooter only changes my vertical impact due to Coriolis by 0.4 inches up (higher).

In fact, my Kestrel measured 4 mph wind at 250 degrees (left to right). without Coriolis or spin drift turned on, Shooter said to dial 1.5 MOA (15.7 inches) for windage, and my group only impacted about 1.5 inches left. When I turn on spin drift and coriolis, Shooter says to increase my windage correction to 2.2 MOA (22.8 inches). If I had adjusted for that I would have shot very far left. And wind flags at 1000 appeared to have about the same effect from wind as the flags right next to me. Not sure how to interpret that data point. Also, I verified pressure to be 25.30 with both my Kestrel and my Leica 1600b.

5. I am as close as i can tell on scope height ... but you say " bore height at the turrets" ... should I be measuring my scope height to something other than the center of the optic? Or am I just totally missing something here?

6. Great article, thanks for the link. It seems Brain's book on ballistics would be a worth while investment.

7. I am not pointing my bullets, and because my goal is to hunt with these bullets, I believe pointing would be a very bad idea.... correct?

So based on everything here especially your experience with this 300 grain Elite Hunter B.C., it sounds like you would recommend adjusting MV rather than B.C. in my application ??

If I drop my MV down to 2705 it brings me right up to where I need to be. I will certainly get more data points shooting at long range. I'm not sure what I will see at shorter distances like 600 yards that won't be easier to see at 1000 or further. I don't have any way to calibrate my Magnetospeed, but it has proven to be very very close to perfect for my 215 berger hybrid out of my 300 win mag. Would be easier for me to accept adjusting MV if that bullet were also impacting similarly low.

 

[bigngreen]

The reason for closer data points is to make sure you tune to the actual trajectory not just 1000 and out, you can start a teter toter effect with your prediction. It also lets you see how the trajectory vs prediction is trending, is it always an moa of or is it growing at a predictable rate, its much easier to pin point the right thing to adjust if you have a trend, it also IDs multiple issues easier so your not tuning things against each other.

I like to put 300, 600 and 1000 on paper as fast as possible, one shot per range to keep conditions tight and round count and heat low while getting solid data.

 

[Timber338]

The reason for closer data points is to make sure you tune to the actual trajectory not just 1000 and out, you can start a teter toter effect with your prediction. It also lets you see how the trajectory vs prediction is trending, is it always an moa of or is it growing at a predictable rate, its much easier to pin point the right thing to adjust if you have a trend, it also IDs multiple issues easier so your not tuning things against each other.

I like to put 300, 600 and 1000 on paper as fast as possible, one shot per range to keep conditions tight and round count and heat low while getting solid data.

Thanks for the response... so are there ever any times when you slightly adjust the BC of any of the Berger bullets? Or are the Berger bullets so well tested that BC is never the source of error? I'm just trying to pinpoint the real world methods that you guys are using to dial in your loads. From everybody's response it really appears that tuning BC is not the favored approach when you're shooting Berger bullets...

I get that real-world results are what we are tuning our analytical models to match... but just looking at the numbers there is a very small analytical difference in tuning the BC vs tuning the MV.

Running the numbers in Shooter with my load.... I originally started with a MV of 2725 @ a BC of .417. My shots were 4 inches low at 1000 yards.
To pull those 4 inches up I can either go with Option A.) tune my MV down to 2705 FPS @ .417 BC or Option B.) tune my BC down to .400 @ 2725 FPS. I think both of these solutions get me within .2" analytically at 1000.

So just to look at the analytical teter toter (I get this is just analytical, and not actual), if you run the numbers at 600, 1000 and 1200. I get the following drops in inches. This also assumes you are shooting due north to eliminate any vertical Coriolos.

MV tune Option A.) 65.8" @ 600 : 252.6" @ 1000 : 405.3" @ 1200

BC tune Option B.) 65.4" @ 600 : 252.4" @ 1000 : 406.2" at 1200

Although it is intuitive, the above numbers make it very easy to see that tuning MV creates more drop up front and less out far and the opposite is true of tuning BC... just highlighting your point of teter toter, and more than that I think you hit the nail on the head with seeing the trend of the load is doing over the entire trajectory. Obviously going to get more and more error as the distance gets beyond 1200 yards when you tune the wrong variable.

At the same time, the analytical difference in drop between options A and B at any hunting distance within 1200 yards is really within the noise for what's going to make a difference on an elk. But I know you've shot a whole lot more than I have at long range, and it sounds like there's a larger real world difference if you don't get your system totally dialed in.

I'll get out sometime within the next couple of weeks to get more data points for this load.

 

[D.Camilleri]

Timber,

I am intrigued by this thread. My go to load has been with H-1000 and the 300 gr Berger OTM, terminal results have been excellent with kills as follows, bull elk 550, 750, mule deer 760, 486, cow elk, 700, 520. I probably am not as careful as you, because I doubt I would worry about 4 inches at 1000 for elk hunting. What I would do though is shoot your same load at 1200 and see the results, if the velocity is indeed off, it will be amplified.

Just curious, have you tried loading up hotter with the reloader 33? I am working on a rl33 load right now using the 300 gr accubond loaded to magazine length. I have over .100 jump to the lands, but so do my bergers. I have loaded up 100 gr of rl33 with OAL of 3.670 and have recorded 2820 fps with the accubond and no visible pressure signs. I have a batch of 101 grs loaded to test. The accubond has a longer bearing surface than the berger and creates more pressure. I am compressing powder quite a bit at 101 but I want to see how it shoots. The accubond has a much different ogive measurement than the berger. I tried loading the accubond short to match the ogive dimension of the berger with 90 grs of h-1000 and stuck my bolt. So changing the OAL is huge in pressure changes. Being .010 off the lands, you will no doubt have much higher pressure due to the lack of free bore. I had also loaded some bergers with 101 grs of rl33, but I didn't have the magneto speed and my chrono decided to not work while I was testing the loads.

Another question, have you verified the kestrel on the days you are shooting? A pressure reading that is off just slightly can make a big difference in trajectory at long range. I have been using my G7 range finder and while I think it works well, I don't think the temp reading is super accurate and the elevation is close, but not perfect, so it leads me to wonder if input data through no fault of yours is to blame.

 

[DocUSMCRetired]

Hey guys, thanks for the responses... this is exactly what I was looking for... you are all saying the same thing that the BC should be accurate so look elsewhere.

Doc, thanks for the accurate list of things to look for. Below is the answers to your questions. I was using the Shooter App to calculate all of my drops. I am shooting this bullet using 93 grains of RL33 and seated to a .010" jump. Not sure of my COAL to the tip of the bullet because I always use a comparator, but I think it is right around 4 inches.

1: I checked my MV several times in previous days, but not during the day I shot at 1000 yards. The temperature was luckily the same as my most recent Magnetospeed V3 data of 34 degF.

2. I'm shooting a 27" Hart barrel with 1:10 twist. Shooter app calculates the stability wtih the exact temp and pressure at 1.86. I believe stability says I should be getting the max .417 BC.

3. I have thoroughly tested out my scope and it does have error which I do have a correction factor entered into Shooter. My CF = .97087

4. I am using the Shooter app, and I did not account for Coriolis or Aerodynamic jump (is this just spin drift?). Although, I was shooting nearly due north... 8 degrees to be exact. Even if I turn on Coriolis Jump and Spin Drift, Shooter only changes my vertical impact due to Coriolis by 0.4 inches up (higher).

In fact, my Kestrel measured 4 mph wind at 250 degrees (left to right). without Coriolis or spin drift turned on, Shooter said to dial 1.5 MOA (15.7 inches) for windage, and my group only impacted about 1.5 inches left. When I turn on spin drift and coriolis, Shooter says to increase my windage correction to 2.2 MOA (22.8 inches). If I had adjusted for that I would have shot very far left. And wind flags at 1000 appeared to have about the same effect from wind as the flags right next to me. Not sure how to interpret that data point. Also, I verified pressure to be 25.30 with both my Kestrel and my Leica 1600b.

5. I am as close as i can tell on scope height ... but you say " bore height at the turrets" ... should I be measuring my scope height to something other than the center of the optic? Or am I just totally missing something here?

6. Great article, thanks for the link. It seems Brain's book on ballistics would be a worth while investment.

7. I am not pointing my bullets, and because my goal is to hunt with these bullets, I believe pointing would be a very bad idea.... correct?

So based on everything here especially your experience with this 300 grain Elite Hunter B.C., it sounds like you would recommend adjusting MV rather than B.C. in my application ??

If I drop my MV down to 2705 it brings me right up to where I need to be. I will certainly get more data points shooting at long range. I'm not sure what I will see at shorter distances like 600 yards that won't be easier to see at 1000 or further. I don't have any way to calibrate my Magnetospeed, but it has proven to be very very close to perfect for my 215 berger hybrid out of my 300 win mag. Would be easier for me to accept adjusting MV if that bullet were also impacting similarly low.

No, that app does not account for Aerodynamic Jump.

By Boreheight I mean center of barrel to center of windage turret.

Correct, don't point.

If the mv change brings everything spot on, then that's the issue.

 

[Timber338]

No, that app does not account for Aerodynamic Jump.

By Boreheight I mean center of barrel to center of windage turret.

Correct, don't point.

If the mv change brings everything spot on, then that's the issue.

10-4. Thanks. I'll post up results when I'm able to get out and shoot again. Looks like I might get out this weekend.

 

[Timber338]

Just curious, have you tried loading up hotter with the reloader 33? I am working on a rl33 load right now using the 300 gr accubond loaded to magazine length. I have over .100 jump to the lands, but so do my bergers. I have loaded up 100 gr of rl33 with OAL of 3.670 and have recorded 2820 fps with the accubond and no visible pressure signs. I have a batch of 101 grs loaded to test. The accubond has a longer bearing surface than the berger and creates more pressure. I am compressing powder quite a bit at 101 but I want to see how it shoots. The accubond has a much different ogive measurement than the berger. I tried loading the accubond short to match the ogive dimension of the berger with 90 grs of h-1000 and stuck my bolt. So changing the OAL is huge in pressure changes. Being .010 off the lands, you will no doubt have much higher pressure due to the lack of free bore. I had also loaded some bergers with 101 grs of rl33, but I didn't have the magneto speed and my chrono decided to not work while I was testing the loads.

Another question, have you verified the kestrel on the days you are shooting? A pressure reading that is off just slightly can make a big difference in trajectory at long range. I have been using my G7 range finder and while I think it works well, I don't think the temp reading is super accurate and the elevation is close, but not perfect, so it leads me to wonder if input data through no fault of yours is to blame.

I do still have my go-to 300 Accubond load that I ran through the paces. With RL33 I was able to get up to about the 2875 where I saw pressure signs. But I found the supreme accuracy I am getting now in the 2730 fps range with the accubond. Just the character of my barrel. I think I was shooting in the 3/4 MOA range around 2800, but the bullets started overlapping each other where I am at now.

When I moved to the 300 Berger, I actually did not change anything ... just loaded the new bullet and off I went to the range. My chrono said I was getting 2725 which may prove to be 20 fps too high. We'll see what happens when I get out to shoot again.

And you've got me convinced to load up 3 rounds with maybe an additional 2 grains and see how it groups at 1000. You are right the Berger has a shorter bearing surface so I could likely get some more FPS out of it. We'll see how that goes too.

And the reason I switched from the Accubond to the Berger, was that I was seeing some inconsistent velocities at least shooting over my Magnetospeed. First cold bore shot was usually at least 40 fps higher than all the rest and sometimes as high as 60 fps higher.... which I think was a unique situation with the burn characteristics of RL33. This may be bull$#!t, but my theory is that the cold bore shot pressured the RL33 more and created higher velocity. Which sort of is consistent with other people testing of the RL33 that shows it really burns well with higher pressures. With H1000 and the Berger, I saw that each consecutive shot was increasing in FPS. Not by much, but still a trend that I would see over and over.

With the Berger's shorter bearing surface I did notice my velocity to become more consistent ... i still see the first shot being higher than the next two or three shots, but it's got a much smaller extreme spread.

So my mind is saying split the difference in burn rate and maybe Retumbo would be dead nuts consistent for muzzle velocity ???? An expensive experiment if I'm only getting about 4 inches of vertical spread at 1000 yards with RL33.

And just because you commented on the "who shoots a 338 RUM" thread about switching to the Accubond, I'm still going to hunt with the accubond loaded in my magazine for short forest shots. If I am set up for a long shot I will just single load the 300 EH since it won't fit in my magazine box anyways. Both of those bullets shot to the same vertical point of impact in my rifle, I only had to move my windage 2 clicks when I switched to the Berger.

And I have not done anything special to verify my Kestrel pressure readings ... not really sure how I would go about doing that anyways. I do always cross reference with my Leica 1600b, and they always seem to bet within 0.02-0.04 inHg which I don't think makes much of a difference.

 

[Timber338]

Timber,

I am intrigued by this thread. My go to load has been with H-1000 and the 300 gr Berger OTM, terminal results have been excellent with kills as follows, bull elk 550, 750, mule deer 760, 486, cow elk, 700, 520. I probably am not as careful as you, because I doubt I would worry about 4 inches at 1000 for elk hunting. What I would do though is shoot your same load at 1200 and see the results, if the velocity is indeed off, it will be amplified.

That is pretty **** impressive to be shooting that many animals at those distances in the field. Not an easy thing to do consistently like you're doing.

I shot two elk last year at 15 yards and 35 yards with the 300 Accubond. Neither of them made it very far.

I have a spot all set up that I watch over a far hillside of oaks and some patches of aspens, the goal being to shoot a bear. And the easiest way for me to find a bear is to hunt over an elk gut pile. I'll get elk moving through anywhere between 350 and a mile. I won't shoot to a mile but I would like to maximize my capability. The sweet spot shots in this spot are really in the 500 - 900 range... So now you know my immediate motivation for dialing everything in and getting some good long range practice.

 

[bigngreen]

Thanks for the response... so are there ever any times when you slightly adjust the BC of any of the Berger bullets? Or are the Berger bullets so well tested that BC is never the source of error? I'm just trying to pinpoint the real world methods that you guys are using to dial in your loads. From everybody's response it really appears that tuning BC is not the favored approach when you're shooting Berger bullets...

At the same time, the analytical difference in drop between options A and B at any hunting distance within 1200 yards is really within the noise for what's going to make a difference on an elk. But I know you've shot a whole lot more than I have at long range, and it sounds like there's a larger real world difference if you don't get your system totally dialed in.

I make very minor BC tunes to most everything I shoot but it at the farther end of trajectory, I try to get as far as I can before looking at tuning it.
The reason I'm really into nailing it down is not really the ranges I'll hunt at but for the ranges I'll practice at, I try to do as much shooting I can at double my effective range, that pits me into a very strong position when I am hunting. It also keeps my tune valid for all elevations and conditions, ibdont end up with a one day tune so to speak. It can be just as easy as plugging a few numbers in and bang your in it but it a trust but verify kind of thing, the more data points the more trust and confidence in my solution.