Bullet seating test

at 300 yards these seating depth variances of .005 make quite a difference.

I'm not expert and don't do super target accuracy work, but yes - depth can have an affect, even neck tension, and alignment - or lack of, are all going to affect consistency, and thus accuracy. I'm sure if you did a test and intentionally added variables into the seating, you'd see a significant rise in group size, how much you can narrow it down going the other way, can't say.

It can make a difference but won’t always be obvious.

JCSC said:

Dang Jim. That’s significant in my book.

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So from this sample of mine which depth would you select?

I have seen 100-yard groups go from 2.48" at 0.010" of jump to 0.60" at 0.050" of jump.

Prior performance does not guarantee future results. (Or, as people like to say these days, YMMV.)

While I don't have anything right now to show you, by all means yes. I'm shooting a 30.06 1974 Remington 700 and I routinely hit 1/2 to 3/4 groups at 100 yards. Hornady 10th powder manual suggests seating my bullets around 3.210 inches. I seat them at 3.257. Previously I was grouping between an 1 inch to 1 1/2 inches. That fine shooting is generally called a "sweet spot". For a lot of different reasons that particular gun likes that seating depth. Some do and some don't. I did find by brother's Ticca T-3 also in .06 likes that seating. On the other hand a Browing BAR did not. Just so you know rifles can have several sweet spots. You just have to find them.

South Prairie Jim said:

View attachment 980515at 300 yards these seating depth variances of .005 make quite a difference.

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JCSC said:

.015?, but I would prefer not having the vertical dispersion.

I’m guessing here, so educate me.

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I went with closer to .018 to stay flat then added some horse power to tighten up but not go vertical.
Our 10 ring is round therefore it's easier to stay on the water line. At least for me

Yes, especially in rifle. That’s my last step after I find a bullet/powder combination that works I then move COL to tighten up the groups.