Ladder Test Input

[sjones]

I finally found some N570 so am doing a ladder test with my 28 Nosler. I first did a seating depth test with the new powder and have attached a picture with 86grs at 200 yds. .270 MOA. This is where I started with my ladder test, shot 1 and increased in .5 gr increments. I was planning on shooting 2 warm up shots but forgot them so shot 1 was the first shot. This is at 500 yds. What I am confused about is shots 6-7 and 8-9 are lower then 4-5 and close to shots 1-3. This was done early morning temps in the low 50s and a 1-2 mph wind at my face. I am thinking 86.5, 86.7 and 87 is where i need to test further with 3-5 shot groups. Your thoughts are appreciated! Thanks

 

[elkaholic]

I finally found some N570 so am doing a ladder test with my 28 Nosler. I first did a seating depth test with the new powder and have attached a picture with 86grs at 200 yds. .270 MOA. This is where I started with my ladder test, shot 1 and increased in .5 gr increments. I was planning on shooting 2 warm up shots but forgot them so shot 1 was the first shot. This is at 500 yds. What I am confused about is shots 6-7 and 8-9 are lower then 4-5 and close to shots 1-3. This was done early morning temps in the low 50s and a 1-2 mph wind at my face. I am thinking 86.5, 86.7 and 87 is where i need to test further with 3-5 shot groups. Your thoughts are appreciated! Thanks

It's not unusual at all to see drops in group at higher velocity then previous shots. Its all about barrel harmonics and why we do ladders. Just work on those ares where 3-4 shots clump. I usually do 2 shot groups at . 3 gr increments.

 

[highdrum]

Was it windy during your ladder? Vertical spread is expected with the ladder, but there is a fair bit of horizontal shift which isn't good and usually indicates the seating depth isn't quite right or there's a problem with inconsistencies, which is usually neck tension causing this horizontal shift. Just because something does well at short range, it not always good out further.
In this ladder you see shots 4,6 are left of grouping, I know these two had less neck tension when seating bullets and noted it. All other shots had maybe 2.5" of horizontal, this was shot at 420y. Vertical spreads can be combatted with finding optimal barrel timing/harmonics, but horizontal is fought with neck tension and seating depth. Hell even primer seating depth comes into play.

 

[sjones]

No there was very little wind 1-2 mph and I was shooting into to wind. ADG brass and all necks turned to same thickness. So your opinion where do you think I should start further testing based on what you see with my barrel harmonics? On your target I would choose shots 7-10 as the place to further test.

 

[highdrum]

Do you have chrono data with the series of 10 shots? I feel you need to test your seating depth a bit more. I generally set all rounds 5k off lands. I take my press to the range with me. I usually shoot 2 shots @ 5k off, if bad, seat another 6k deeper and shoot 2 more, repeat. Once I find a good 2 shot group, 1 shoot the 3rd. If it's tight, I shoot 2 more groups +.003 and -.003 from the known good seating depth. Usually you can find a node 3-5k wide where it shoots tight groups with the same poi. Say it's 2.812-2.817 that shoots in your node. I'd seat @ 2.816 as you'll have 4k throat burn that'll stay in your window before accuracy falls off. Lots of people are shooting ladders with paired charges say: 84.5 x 2, 85 x 2, 85.5 x2 and so on. If the vo spread is large on the two shots of same charge it'll usually show on target with spreads.
Did you find pressure on the ladder? If so where and what was charge? Usually you can see that 1.5gr below psi will shoot well.

 

[sjones]

No I don't have any chrono on my shots. I have a Magneto but was going to wait till end to see the speed. With my rifle the Magneto REALLY changes the point of impact. For seating I did the Berger seating test and the 2nd round did 10k difference and then 5k. I really didn't see any pressure signs but the bolt may have been a little different at the upper 3-4 shots. I can try that again and see where the bolt is harder to open.

 

[highdrum]

Your seating depth at 200y looks good. I'd shoot 2 more groups, one +002 and one - 002 if it all holds good grouping, then pick a spot on the longer half the range and use it. Then run your ladder again shooting 2 shots per charge weight. Just my recommendations. Things will come together. Another thing I always do before a ladder. Check trq on rings and action screws prior.

 

[sjones]

Thanks for the info and will try the 2 shots per charge. I have sent my scope in to check and see if the vertical adjustment is off. After the ladder test I was trying a test at 86.5 grs and 3 shots all over the place not touching a thing. So yes maybe I had a torque problem or scope. After I get the scope back on I will let you know my results. Thanks again. You close to Missoula?

 

[highdrum]

Thanks for the info and will try the 2 shots per charge. I have sent my scope in to check and see if the vertical adjustment is off. After the ladder test I was trying a test at 86.5 grs and 3 shots all over the place not touching a thing. So yes maybe I had a torque problem or scope. After I get the scope back on I will let you know my results. Thanks again. You close to Missoula?

No problem, hope it's not a scope issue. I live in Kalispell but am on the other side the state farming a lot on my family's place.

Here's a problem with the 28N and using powders that's burn very hot like N570, they eat throat for breakfast. Every 10 rounds, you'll lose a thousandth, so after 30 rounds, you can get out your seating node from lands eroding. Retumbo is better for this application, but you lose some speed. RL33 is good too, but is quite dirty and temp sensitive.

 

[highdrum]

Are you using nosler or adg brass? Make sure you can slip a bullet back into your fired case neck if using nosler brass. It's tight clearance in a lot of chambers. Adg has thinner necks and is a lot better brass in my opinion.

 

[sjones]

ADG and the necks are turned and yes ADG is a lot better.

 

[highdrum]

ADG and the necks are turned and yes ADG is a lot better.

Nice......Cci250 or 215m? Some say cci give lower velocity spreads but I've observed very little of that from my testing.

 

[sjones]

I'm using CCI in my 28, my 300wm likes Federal.

 

[skipglo]

I finally found some N570 so am doing a ladder test with my 28 Nosler. I first did a seating depth test with the new powder and have attached a picture with 86grs at 200 yds. .270 MOA. This is where I started with my ladder test, shot 1 and increased in .5 gr increments. I was planning on shooting 2 warm up shots but forgot them so shot 1 was the first shot. This is at 500 yds. What I am confused about is shots 6-7 and 8-9 are lower then 4-5 and close to shots 1-3. This was done early morning temps in the low 50s and a 1-2 mph wind at my face. I am thinking 86.5, 86.7 and 87 is where i need to test further with 3-5 shot groups. Your thoughts are appreciated! Thanks

Looking at your 500 yrd. target I would do two or three shot groups using no.2 and no.3 loads as you have them now. They are showing best! But singles never give a true representation. To easy to pull a shot!