Seating Depth Results

[smoothie25]

Hi All, I'm working up a load for a new bullet. I found a powder node that had SD 11, ES 21.

Ruger American 243
Sierra Gamechanger 90gr
H4350
Fed 210
Win brass (fired several times in the rifle, trimmed and annealed)

I shot the ladder at 2.26" which is mag length. I used Berger's suggested seating depth test and loaded at 2.22", 2.18" and 2.14". These are my results. Let me know your thoughts on whether or not I'm close or should seat deeper. Should I try another primer?

Also, any idea why my first two shots were nearly touching then 3rd shot is off? I shot three bullets with no break between shots then waited to cool to ambient temp before shooting the next group. It's a sporter barrel so barrel warming up?

 

[Wags]

Is that the only bullet you've tried?

 

[smoothie25]

Is that the only bullet you've tried?

I shot several hundred Nosler Varmageddon 70gr thru this gun. They shot MOA out to 500. Just wanted to try something else I could get my hands on since inventory has been low lately.


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[RS_Non-Res]

I've been told to work out the seating depth first. Then matrix the powders and charges. Also 5-shot min, 7 better for reliable stats. Barrel temp often makes a real difference, the only uniform possibility is "cold", so it takes time.

 

[Vern400]

3 shots is statistically easy to trick yourself with. It can prove you're bad, but can not prove you're good. I don't know 243 well but my 7.62 likes some bullets (most) but refuses to shoot others well. Try matching the bullet free travel from the old cartridge that's accurate. Or did you change everything at once?

 

[EdP]

I agree with Vern's comment about 3 shot stats not being adequate to select a load or seating depth and 5 being the absolute minimum. To avoid heating a barrel to the point that it affects POI I allow 3 minutes cooling time between shots and keep it shaded from the sun. That method is slow and somewhat tedious but has worked for me on numerous rifles. An old fashioned egg timer travels in my range box for that purpose. Another potential cause of flyers is letting one cook in the chamber too long. A cartridge can always be pulled if something delays making the shot.