ladder testing newbie questions

[ronedog]

I've finally gotten back to reloading and trying to figure out my recipe for my rifle. Before I ask my question here's the setup. Winchester Model 70, 300 WSM, 20MOA picatinny base with weaver rings, Vortex 6x20x50mm, trigger pull at 3.5 lbs.

Im shooting 185 Berger VLD Hunting bullets in Winchester brass (fireformed with 2 rounds through each brass), Neck Sizing only, using IMR 4350 (ran out of H4350 and can't find any in local stores), someone suggested imr4350.

Here's my question. I started at the starting load of 55.5g and worked my way up to the max load of 62g. Loaded 3 bullets of each at .5g increments. I decided I'd try doing a ladder test this evening and ran out of light, but I did manage to get 10 shots in. Shot 3 foulers to start out, let the gun cool down and began the ladder test.

I started out at 55.5g, shot one shot, then went to 56g shot one shot, then went to 56.5g shot one shot and so forth, working my way up the ladder. The target was 511 yards away. I'm wanting to shoot to distances of up to 800-900 yards, so I figured 500yds was a good place to see the vertical climb of the different powder charges.

My target is 5 feet tall and 3 feet wide, I put a horizontal line in the middle and a small vertical line in the middle making a cross. My aim point was directly in the middle of the cross. The lower powder charges were about 18 inches below horizontal line, but as I worked my way up the ladder I had 2 charges (56.5 57.0) that were right on the horizontal line, then the next charge (57.5) jumped above the horizontal line about 5 inches, and the higher charges continued up the ladder above the horizontal line higher and higher.

So I got to thinking, at 511 yds I had 2 charges that nailed the target at near the same vertical plane. Is there any reason to continue with my ladder test now that I found 2 charges that hit near exact vertical point of where I was aiming, while the other charges either fell below, or were too high? My logical thinking says to stop the testing and waisting of powder/bullets and move to fine tuning the seating depth of the 2 charges. I guess I'm really thinking that if I aimed at a spot at 511 yds and hit it twice, and all the other charges were not a close to this, even though I aimed at the same point on the target, then wouldn't that be the best powder charge to use?

I'm a newbie to long range, I've read a bunch, but finally got time to go out and put it into practice, but I never read anything about what I'm thinking, so just looking for anyone's guidance and if you think I should continue shooting all the other bullets, or if I should stick with those two charges and move to seating depth adjustments.

Thanks in advance.

Rone

 

[Unofficial Gun Addict (UGA)]

Hi... So if I get this right... You currently have a window of .5 gr which appears to keep the same vertical plane? Now I'm wondering whether that was only with 2 bullets? If so, I'd definitely verify before settling on a load range. Two separate shots with different loads most likely isn't going to provide you with enough information as to consistency... But it is a good place to examine more closely.

If you decide that you have a nice flat horizontal range between these two loads... Then I'd start testing to see how wide the range actually is... By testing in .1gr increments higher and lower than the two loads you settled on.

And I know this might fly in the face of some of those that ladder test... But just because a load looks good for vertical alignment, doesn't mean it might not be squirrelly when it comes to horizontal shift. I've seen too many loads that could punch the same line vertically, and had great es/sd, but wandered left and right. I try to look for a load that gives me the best of both worlds for the range I'm shooting.

I just measure height and width of my group.... Like a rectangle... To determine if it's going to work for me. Unorthodox perhaps by benchrest standards, but I'm using my loads for hunting... So if I can keep it in a 4" by 3" box at 600... I call it good.

So... With this in mind... Someone else's advice might fit your situation better. Either way... Best of luck and shooting to you!

 

[BountyHunter]

shooting to a crossed X and picking the bullets that hit closest is not a ladder test!

You should be looking for a grouping of bullets that group together regardless of impact point as you go up in powder the POIs will move up the paper.

That is why you zero the gun after load development.

Here is my way of doing a ladder


Here is an explanation of how I ladder test step by step.

My methodology is pretty similar to audette method except I double check everything with a chrono after I have done basic research to determine, bullet,primer, and powder combo I want to use/test for each ladder. Now this might be many reloading manuals, others recommended loads, Qload, etc, but I find a "suspected" powder, primer, bullet and case and then work a load that is normally about 2-5 grains below max to 1-2 grains over at .2 to .4 increments depending on case size. Normally this is 15-25 bullets only with 4-5 extra of the lowest charge for initial zero on the other target.

I use the smaller increments as I am looking for a node that often is only .5 to max 1.0 wide and this gives me a easier way to determine it.

1. Shoot ONLY in early morning or evening in no wind conditions.

2. Minimum of 300 yards prefer 400. I have found that seems to be the ideal distance for enough vertical dispersion as the bullets walk up and close enough to see each separate bullet impact with good spotting scope on white target. Shorter makes it to difficult to determine impacts and longer makes it too difficult again to see any impacts.

3. 35P chrono is used. This is absolutely key. Brian Litz's new book confirms why the Oehlers are the best chromos.

4. Minature paper target at bench to plot each round and another sheet to write down each MV for each round. That way I do not lose track of any bullet shot as each is numbered on plot sheet and anytime I go down range to verify impact. I also mark each shot on the 35 P paper as it is shot.

5. Minimum of 1 minute between shots from starting dirty bore, I usually zero at that distance on another target at the side to confirm accurate zero for bottom of ladder target which is normally large plain white cardboard with 1" aiming dot near bottom. I use .3 grain for large cases and .2 for smaller cases as increments.

6. If I am not 100% sure of bullet location, I either walk down or I often use use colored magic markers (4-5 colors) alternating on bullet tips which show up on target. No they will not vary impact points on target. That is used all the time at 1K BR to identify any crossfires on your target.

7. MV as you go up will be linear (ie roughly same FPS each bullet) until you hit a node and then it tends to decrease dramatically for that 2-4 shots and then jump linear again. You will see 3-4 rds with small MV variances normally in the node and then jump dramatically again. You can see on a magnum a jump of 20 FPS and then 3 bullets around 6-8 fps along then it will jump again back to around 20. This is only an example, not always.

Combination of bullet AND MV grouping confirms node and is usually easy to see when you compare the two!! You will have multiple bullets with similar vertical impacts and very low dispersion on MV.

8. I pick a middle node, shoot groups to confirm basic accuracy and ES, SD nodes. I normally find two, maybe three nodes, and one will be in the MV range I am looking for. Many times the top one is at the starting of high pressure point, so often do not use that one. Middle of the node gives me enough variance on temps and other factors that I am not out of the node on any given day. I do not focus on the lowest ES/SD. Once I find a node then it is an "acceptable ES/SD and tight grouping that is confirmed. I normally shoot for single digit ideally but low teens is acceptable with the grouping.

I determine pressure by case head expansion measured with a blade micrometer, primers (but not always accurate as some are softer than others and can be misleading), sticky bolth etc. It is a combination of everything that leads me to determine I am at high pressure. I take it until I see firm signs of pressure and then stop even if I have not shot all the shots IF I am at an acceptable MV and see good nodes.

9. I then try groups at various seating depths at my best grouping and see what depth it likes. For a single shot gun start, .010 in the lands and come out. Magazine gun, start at max magazine COAL and in from there. I start .010 in, come out at .030, .050, .080 and .120 IF a single shot gun. One will be much tighter and then work in between to find the place normally down to .010.

10. If the gun will not shoot 1 MOA, that makes shooting a ladder a little difficult as you do not know what is the real vertical or 3-4MOA grouping "inability", so IMO it is not for every gun.

11. If a gun will not shoot with all this, then another ladder with another powder or bullet combo.

 

[ronedog]

Guys, thanks for the reply's. Excellant information. I decided last night I should shoot another 10 shots and work my way back down the ladder. I'll take your advice and finish the ladder test with the 3rd round tomorrow. I'll take some pics and post them to make sure I'm analyzing this right. Thanks again!

 

[ronedog]

I ended up shooging the rest of the ladder test and settled in at 57.5 g, but forgot to take a pic before I trashed it. Thanks for the help.