Ladder testing results/advice

[NVDesertHunter]

Finished ladder testing with my 280AI shooting Barnes LRX 145 grain. The shots were taken at 250 yards. I'm leaning towards the #10 load (54.3gn). My question is "during ladder testing why is horizontal shot string more important than vertical shot string." Since I'm using non-lead bullets, I would like to shoot the highest velocity that is accurate. Hence the #10 load over the #9. Any advice would be helpful. Thanks

P.S sorry that the picture is rotated. Not sure how to fix it.

 

[belly-deep]

Horizontal stringing on a ladder is not important at all. You're looking for a vertical cluster while paying no attention to the wind, which is what most of the horizontal stringing comes from.

Why do you think 54.3 is your sweet spot? I'd maybe re-shoot two more tests with loads #8-12 at a little bit longer yardage (400) and see what it turns up.

 

[whiskeydog]

54.3 looks good, although in my opinion 54.0 is a better average. Narrowing it down with more loads from 53.7-54.6 or shooting again at 400 like mentioned above would both be good...although you're probably good just sticking with 53.7-54.3.

As for your questions, there are numerous factors that can cause horizontal or vertical stringing. However, simply put, horizontal deviance is often shooter error (and can be corrected later) such as slight changes in grip or trigger pressure. Vertical stringing is often a result of the charge being used, and that is what you are trying to isolate in a ladder test. Somebody can probably explain it better than I, but my understanding is that one cause of the vertical string is due to barrel harmonics. The barrel oscillates up and down when you fire...one load may have the bullet leaving the barrel at the top of the curve while another may have it exiting the barrel at the bottom. This is the reason why floating a barrel improves accuracy; if it's not floated, there is a restriction on the natural oscillations. You are trying to find a sweet spot where a group of loads produces the same exit point and thus gives you consistent hits on target in the horizontal. It looks like 53.7-54.3 are about where it's at...
I wouldn't worry too much about 40FPS difference...run the numbers...it's not going to matter that much. Use the most accurate load.

https://www.bing.com/videos/search?...5C1465F7DF3B1CC1146A5C1465F7DF3B1&FORM=VRDGAR