bullet seating depth and pressure

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Pomme
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bullet seating depth and pressure

#1 Post by Pomme » Mon Jul 09, 2018 10:50 pm

I was under the impression that a deeper seating depth, therefore a shorter oal would create more pressure but the Nosler reloading tutorial on youtube says the oposite. What are your thoughts?
Here is the link, go to 3:27 https://www.youtube.com/watch?v=p908IOpMfP8

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Marlene
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Re: bullet seating depth and pressure

#2 Post by Marlene » Mon Jul 09, 2018 11:28 pm

In a big bottleneck rifle cartridge, the amount of space taken up in the case by the bullet has a very small influence on initial case capacity, but the cartridge operates at much higher pressures with bullets usually starting closer to the lands, which makes jump to lands much more influential on pressure. In a pistol cartridge like 9mm, seating depth has a much larger influence on initial case capacity, but at magazine length bullets are not going to be close to the lands, so jump to lands distance has very little influence.

The answer is that your impression was correct, but also that the guy in the video is correct. Different situations behave differently. It is complicated enough that people generally do a terrible job of explaining it.
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Pomme
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Re: bullet seating depth and pressure

#3 Post by Pomme » Tue Jul 10, 2018 9:37 am

got it. It is a complex subject!

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