Mikecr
Well-Known Member
Tension is not friction, so the feel of seating, or outright measure of seating force, can be completely independent of actual tension.
If you take necks to squeaky clean, bullets to squeaky clean, and partial NS to cause an interference fit of -10tou of cal, you will experience enough seating force that you should know you're damaging bullets.
In contrast, leave carbon in necks, coat bullets with a slippery dry film (like WS2), and NS to leave an interference of -1thou of cal, you'll find seating force is very low, and very precise.
Fire the two across a chronograph,, NO DIFFERENCE in MV.
Now size two necks down to -1thou interference, one sized 1/2 seated bearing length, the other full seated bearing length.
Fire the two across a chronograph,, SIGNIFICANT DIFFERENCE in MV.
This is because neck tension = spring back force per area it's gripping.
Bullets are not pushed out of necks. They're released from necks.
And with so much as a billionth of an inch neck expansion from cal, a bullet is freely loose. It is often implied that low neck clearance equates to higher pressures. This is hogwash. You can actually have very near zero neck clearance, and it makes no difference to bullet release. The only time a problem occurs is with interference fit between chamber and necks. Here, you have an extremely serious hazard, and so it's prudent to ensure it never happens, even from any grime in the chamber.
But when it comes right down to it, 1,000s of an inch clearance functions the same as 1,000 miles of clearance.
If you take necks to squeaky clean, bullets to squeaky clean, and partial NS to cause an interference fit of -10tou of cal, you will experience enough seating force that you should know you're damaging bullets.
In contrast, leave carbon in necks, coat bullets with a slippery dry film (like WS2), and NS to leave an interference of -1thou of cal, you'll find seating force is very low, and very precise.
Fire the two across a chronograph,, NO DIFFERENCE in MV.
Now size two necks down to -1thou interference, one sized 1/2 seated bearing length, the other full seated bearing length.
Fire the two across a chronograph,, SIGNIFICANT DIFFERENCE in MV.
This is because neck tension = spring back force per area it's gripping.
Bullets are not pushed out of necks. They're released from necks.
And with so much as a billionth of an inch neck expansion from cal, a bullet is freely loose. It is often implied that low neck clearance equates to higher pressures. This is hogwash. You can actually have very near zero neck clearance, and it makes no difference to bullet release. The only time a problem occurs is with interference fit between chamber and necks. Here, you have an extremely serious hazard, and so it's prudent to ensure it never happens, even from any grime in the chamber.
But when it comes right down to it, 1,000s of an inch clearance functions the same as 1,000 miles of clearance.
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