Reply With QuoteNice write up. I use the same charge in my 260 with 142 smk and 42.5 gr H4350. 5 rounds could be covered with a bic lighter at 600 yds
Over the last couple days I've done some load development on a rifle that was already shooting pretty decent. I really wanted to make sure I wasn't losing any points to vertical dispersion in 600 yard F-Open matches. Therefore, all the testing here was done at 600 yards. This is just an example of one way to do load development and I'm certainly not an expert at shooting them or reading the results. I must admit that I've had some help interpreting this ladder as well as guidance on what to do next. Anyhow, its just an example so that others can possibly learn and become better shooters. One thing I did not test was jump/jam. I already knew that this rifle liked the 142 SMKs about .030 jump so I took that variable out of the equation and loaded everything at .030 jump.
Initial ladder test
(tested from 51,000 psi chamber pressure up to 61,000 psi) just under max
What I gathered from this initial ladder test is that the least amount of vertical occurred between 42.1 and 42.7 grain charges (shots 3,4,5).
2nd stage test
I loaded (2) ladders in 0.1 grain increments from 42.1 to 42.7 and shot them at the same POA at 600 yards.
This double ladder showed me the least amount of vertical between 4 & 5 or 42.4 & 42.5 charge weights. This ladder was confusing to me but in the end you look for the least amount of vertical over several charge weight in a row. In this example I noticed 42.3 had a wide vertical spread but then 42.4, 42.5 & 42.6 were decently close with 42.7 increasing significantly.
Final stage test
I loaded 4 shot groups of 42.4 & 42.5 & 42.6 and went back to check at 600 yards again. I don't have a pic of 42.6 but it was just over 1/2 MOA.. 42.4 had some vertical but still managed to print a .365 MOA group. 42.5 is the clear winner in the vertical dispersion race and was able to print a group of .215 moa at 600 yards with just over 1" of vertical!!!! WOW... Conditions were ideal, no wind at all and 60 degree weather.
Nice write up. I use the same charge in my 260 with 142 smk and 42.5 gr H4350. 5 rounds could be covered with a bic lighter at 600 yds
Great Post Cowtown!
The Dunning-Kruger effect is alive and well.
Nice work and great.results
Very nice load workup! I do believe you're onto something! Lol
Scooter
Hey, just so ya'll know... This rifle reserves the right to bite me in the azz at any time especially during a match... LOL..
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