Did a ladder test to find a load for my 300 Win Mag

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5point9straight6

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And it suggests a problem. Here's what I did: I used Speer 180gr SPTZ BT bullets, Win cases, CCI 250 (Magnum) primers, and IMR 4831 powder. I used loading info from the Speer manual and ramped the charge from 69.0gr to 72.8gr, which is near the maximum listed for the cartridge in this manual. I loaded 20 rounds. I did not have a chrony at hand, which I should have procured in hindsight. The rifle is a Browning M1000 Eclipse with BOSS and a Zeiss Conquest 6.5-20x50mm scope. I was shooting from a gun rest on a bench. Steady as can be.
Here is a picture of the target paper (@200 yards), with the sequence of shots:

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(use right click and open in new window, if the image link appears to be broken)

There is no pattern to this whatsoever. Thus gun should do a lot better than that and did so in the past. I'm beginning to think there is an issue for a gun plumber to figure out.
 
Depends on the gun. Some guns have lower poi changes than others with different loads. Yours appears to be one of those... Which I would rather have, BTW, than one that creates a larger ladder.

What is the gun you are shooting?
 
If you are doing a ladder in order to find the best grouping, non vertical stringing load for long distance use, 300 yds or meters is about minimum test distance. Shorter distances than 300 seems to make determination of the above criteria more difficult and can lead to excluding loads that could be excellent beyond 100 or 200 yds/meters.

EDIT to add.....what where the number of rounds shot that were loaded with each incremental load. For example 13 14 and 15 look like a higher velocity and have little relative vertical stringing, compared to the whole target. Where they all the same powder load and seating depth or close to one another in powder charge?

I usually do 3-4 rounds minimum @ each incremental powder charge and shoot them round robin, then I look for the best non vertical grouping and see what powder charge(s) or if lucky what one charge produced it. Then I would refine that load further with more testing/seating or test that load at whatever longer distance I was going to use that load.
 
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I did the test according to some websites and threads on CGN. Just 20 rounds, with the powder charge increased in 0.2gr increments.

The gun is a Browning A-bolt 2 M1000 with BOSS.
 
Accuracy Load: IMR-4831/ 71.6grs. 3000fps/ 3598ft. lbs.
Hunting Load: IMR-7828/ 76.8grs. 3100fps/ 3841ft. lbs.

From the Sierra Manual. For accuracy you should be in the right area.
If I read your info correctly, #11 should be 71 grains and #14 71.6 grains, and that was perhaps what "skypilot" was suggesting.
20 appears to be out of the picture which should be in the Max range.
No Chronograph readings?
 
I may as well write out the load data here.
1) 69.0; 2) 69.2; 3) 69.4; 4) 69.6; 5) 69.8; 6) 70.0; 7) 70.2; 8) 70.4; 9) 70.6; 10) 70.8;

11) 71.0; 12) 71.2; 13) 71.4; 14) 71.6; 15) 71.8; 16) 72.0; 17) 72.2; 18) 72.4; 19) 72.6; 20) 72.8

Unfortunately there was no chrony available.

What do you think about 6,7,8,9? They appear to be separated only 1/2 to 3/4" vertically.
 
In the past I always seated my bullets based on the C.O.L specification given in the reloading manual, but I see how this does not necessarily make the most sense.
So I did some more reading on seating depth and how to gauge it. I used a partially sized case and a bullet loosely fitted to determine the distance between the bolt face when closed and the lands... I did this for a couple of calibers now (said 300WM and a 308 Win) and I used a FMJ bullet, as the tip is not prone to deformation - these are going to be my gauging rounds, based on which I will increase the seating depths in the future now. Picture of the results below.

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The respective rounds on the left are the gauged ones. The ones to the right show how I used to seat them to meet the COL spec, for comparison. Note that I included one round loaded with the FMJ bullet seated to the crimp groove among the .308 examples. This shows that the difference in seating depth is 0.069" (1/16" easily). For the 300WM the difference between the gauged round and my "normal" round was even greater, 0.1795" (measured by lowering a seater die onto each head). Now I figure that my bullets were seated quite deep in the past, perhaps too far off the lands.

Can anyone comment on this please? How much distance is a good starting point?
 
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These kinds of threads are saturating the hand loading section of CGN and in my opinion they are all hogwash!
If you have a good barrel and it is properly bedded, slight changes in powder charges or slight changes in bullet seating, have no effect, whatsoever, on the rifles accuracy.
I have had this on here before, but I will repeat it. From the book by Warren Page, The Accurate Rifle. If you are unfamiliar, Warren Page was probably the most accomplished rifle shooter, ever.
Here is what he says about loading for long distance shooting.



In another section he states, "There is only one way to load a 308 Winchester-full."
 
Perhaps(in lieu of having to do a complete do over) you could load 6,7,8,9 and 11,12,13,14 and re shoot at 300 yds. To keep the integrity of the test(to keep me from confusing myself) I set a video camera up near the target to document the order and location of hits.

Basically you wish to find the highest shots on target with the least vertical stringing.(which should indicate the highest velocities coupled with the least erratic or least sensitive to slight powder charge/ seating depth variations.(the built in tolerances/accuracy in the powder scale and dies for example)

Just as a reference for you(as I don't know your previous experiences) I have seen numerous "bughole" loads at 100 yds be quite stringy at 300 meters and beyond and I have seen some less than "same hole" rounds @ 100 yds be sub MOA @ 400+. It is one reason to ladder @ 300+ as one is looking for accuracy nodes at distance not accuracy nodes up close.

The bottom line is that if the total combination is capable of accurate fire and you are as meticulous as you seem, you should have no problem recognizing the best load and "good" load either side of it @ 300 yds/meters, especially doing so at .2 gr increments.

There are some extraordinary marksmen on this forum and I'm sure they will be along to help you narrow any potential issues and help you reach your goal.
 
5point9straight6 said:
I may as well write out the load data here.
1) 69.0; 2) 69.2; 3) 69.4; 4) 69.6; 5) 69.8; 6) 70.0; 7) 70.2; 8) 70.4; 9) 70.6; 10) 70.8;

11) 71.0; 12) 71.2; 13) 71.4; 14) 71.6; 15) 71.8; 16) 72.0; 17) 72.2; 18) 72.4; 19) 72.6; 20) 72.8

Unfortunately there was no chrony available.

What do you think about 6,7,8,9? They appear to be separated only 1/2 to 3/4" vertically.
Click to expand...

Sorry if I'm misunderstanding this, and if I am then just dismiss it lol but did you load just 20 individual rounds at different charges going up in .2 increments? I would have thought that you would need 3 rounds of each charge weight and shoot a group for every step up in powder.. That would be more like 60 rounds total fired... Again I may have misunderstood, but how can you find the most consistent and accurate load by just shooting 20 bullets at a target that are all different charges..

Edit: I also just may not be familiar with this style of ladder test, so, sorry again if that's the case as my experience is somewhat limited
 
The point of a ladder test is to find the range of powder charge weight that results in the smallest increase in velocity. I.E you increase/decrease the powder charge but the velocity barely, if at all, increases/decreases. The reason for this is so that when you are shooting large numbers of rounds, the deviation in velocities is the smallest, so that they all drop the same elevation and all you have to worry about is the wind.

At shorter ranges, like 100/200yds, you are more concerned with barrel harmonics to get the best accuracy, i.e the movement of the barrel at the moment the bullet exits the muzzle is the same each time. For that, you would do an optimum charge weight test. http://optimalchargeweight.embarqspace.com/ocw-instructions/4529817134
An OCW is looking to keep the same point of impact with increasing powder charge weight.
 
Alpheus said:
The point of a ladder test is to find the range of powder charge weight that results in the smallest increase in velocity. I.E you increase/decrease the powder charge but the velocity barely, if at all, increases/decreases. The reason for this is so that when you are shooting large numbers of rounds, the deviation in velocities is the smallest, so that they all drop the same elevation and all you have to worry about is the wind.

At shorter ranges, like 100/200yds, you are more concerned with barrel harmonics to get the best accuracy, i.e the movement of the barrel at the moment the bullet exits the muzzle is the same each time. For that, you would do an optimum charge weight test. http://optimalchargeweight.embarqspace.com/ocw-instructions/4529817134
An OCW is looking to keep the same point of impact with increasing powder charge weight.
Click to expand...

This represents the latest thinking on this subject and the OCW technique is employed by the most serious international long range competitors these days. It is used by both the Canadian and American Palma teams, for example. The principle, as explained by Mr. Newberry, is that if your brass is slightly out of spec, or if your powder lot is slightly different, or if your charge weights are off by one or two tenths, your shots will still land in the same spot because there is a sweet spot that is predictable in your loading range. This sweet spot will cover approximately half a grain lighter or heavier than your optimum in cartridges like the .300 Winchester Magnum. By contrast, if you choose a load that gives you incredible accuracy in one spot only (i.e. 72.6 grains), then your shots can go to different places if the temperature and pressure change slightly, for example, or if you accidentally throw 72.4 grains.
 
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