Bullet Jump & bullet to case concentricity...

[Humble284]

I have a question... Is bullet to case (as loaded) concentricity more, less or of the same importance when not seating bullet to the lands?

In my testing of loads for my 7mmRemMag, I found that seating to the lands, 0.030" jump and 0.060" jump all seem the same in terms of accuracy. When shooting I have noticed that 0.004 bullet runout opens my groups when seating to the lands. When I seat for either 0.030" or 0.060" jump, the 0.004 bullet runout does not seem to open the group.

I average about 0.002" bullet to case runout with about 7%-10% somewhere between 0.003"-0.004".

Is this because the bullet is aligning in the moment that it engages the lands when it can jump versus touching the lands? I think that would make sense, but I would like some other observations.

 

[308sako]

Re: Bullet Jump & bullet to case concentricity...

Deleted in protest!

 

[Humble284]

Re: Bullet Jump & bullet to case concentricity...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 308sako</div><div class="ubbcode-body">T...into the lands crooked... accuracy suffers, but if you allow the bullet to "bounce" into the lands... accuracy gains. ...

Not even an opinion... just a guess too! </div></div>

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Yes, it is interesting. I have observed this on a few dozen targets over the past year. I figured it was time to ask some shooters. I think the only reason I can observe this is because of the odd harmonics of my rifle allowing for three equally accurate bullet seatings. Otherwise, how would you be able to tell?