I usually test the case mouth with a bullet. If it looks like a tight fit, I continue.

Normally the grip is compromised and will not be constant. The only way to resize is with the decapping pin removed from a full length die or with a neck sizing bushing. Using a normal die will have a very tight fit, but can be rectified with a mandrel 2 thou smaller than calibre.

No, you don't have to resize if you use a collet puller.

Moving the bullet in the case neck doesn't change neck tension, and pulling bullets if just moving the bullet out. Competition shooters typically load their ammo long, then seat to the correct depth the day before.

The only condition is that the bullet is removed straight with a collet type puller.

Moering it in a kinetic hammer might cause the bullet to exit at an angle, stretching the neck on one side.

No, you don't have to resize if you use a collet puller.

Moving the bullet in the case neck doesn't change neck tension, and pulling bullets if just moving the bullet out. Competition shooters typically load their ammo long, then seat to the correct depth the day before.

The only condition is that the bullet is removed straight with a collet type puller.

Moering it in a kinetic hammer might cause the bullet to exit at an angle, stretching the neck on one side.

I'm miles away from being a precision reloader so this observation doesn't come from first hand experience or experimentation.

Pulling a bullet out of the neck before replacing it with another and pushing a seated bullet in further can't cycle the neck brass the same. If you take one out and then push another one in you have additional springback and stretch cycles vs just pushing the same bullet further in. However insignificant the effect of that difference is it is different.

The springback will work harden the neck, but to a very small degree, and practically should make no difference.

This is for a .284 at 1000 yards, rounds completely pulled and re-seated.

https://www.youtube.com/watch?v=LDS7YY3UzOY

Another assumption is that the rounds were not crimped.

I have no idea how a crimp would affect this, it may change things significantly.

Bullet weld, something I fear.

Bullet weld, something I fear.

Something I saw for myself when I pulled 30-06 ammo that was given to me. I just wanted the brass anyway, so I pulled the rounds. Some were so tight it took maximum effort using a press mounted collet puller. There was a green layer of something between the bullet and the case neck. I was glad I never tried to shoot any of them.

you know my history and gifted stuff, shit you not, I have broken 2 kinetic hammers saving brass or wanting bullets from old stuff.
What is old though ??
My last 2 years loads, or 10 year old loads?

Its the fingers touching bullets that causes the issue.

you know my history and gifted stuff, shit you not, I have broken 2 kinetic hammers saving brass or wanting bullets from old stuff.
What is old though ??
My last 2 years loads, or 10 year old loads?

Its the fingers touching bullets that causes the issue.

I once almost blew up a rifle with a reloaded cartridge. Come to think of it, it was not that old - definitely less than five years and probably closer to two years.

How fast does a "chemical weld" occur?

One of the older resizing lubes caused chemical welding. All the Lee, olive oil and Imperial sizing wax have not caused any problems.

One of the older resizing lubes caused chemical welding. All the Lee, olive oil and Imperial sizing wax have not caused any problems.

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And sweaty hands.
One of the ways of bonding bullets during production is the use of .5% acid dip which basically corrodes the case to the lead - like a bolt thats rusted solid. Sweaty hands can do this between case and bullet.
Its a thing that scares me proper.

I have broken 2 kinetic hammers saving brass or wanting bullets from old stuff.

Tip: push the bullets just a fraction into the case neck with the press and bullet seating die. It saved lots of time and energy with lacquered milsurp.

And sweaty hands. One of the ways of bonding bullets during production is the use of .5% acid dip which basically corrodes the case to the lead - like a bolt thats rusted solid. Sweaty hands can do this between case and bullet.
Its a thing that scares me proper.

How does one solve this? A wet cloth nearby, gloves, what else?

do not not touch the seated part of bullet.