Question on lead bullet obturation in 357 mag GP100 cylinder throats

[oldcrab]

Just trying to educate myself on shooting lead 158gr swc's in my two GP100's:

When you have a load that is not too-low in max pressure for the BHN you are shooting, will a bullet start obturating right in the cylinder throat, or does obturation only happen when the bullet has passed into the forcing/cone-barrel portion of the revolver?

Thanks for your thoughts on this.

Have a nice weekend, and "Go-Huskies"!!!

 

[The Norseman]

Good morning. Starline Brass site has a very
informative Article about Lead Bullets and
obturating.

Go to Starline main page, scroll down to
about middle, and look at the "Learn More"
area.

The Best to you and your Endeavors

 

[epags]

I think this is what @The Norseman was referring to: https://www.starlinebrass.com/articles/lead-alloy-bullets-handloading-lead-bullets/

 

[The Norseman]

Yes that's it. Thank you for providing Original
Poster with link.

 

[oldcrab]

Good morning. Starline Brass site has a very
informative Article about Lead Bullets and
obturating.

Go to Starline main page, scroll down to
about middle, and look at the "Learn More"
area.

The Best to you and your Endeavors

Norseman, thanks much for your direction... I went to Starline's site and found the article on lead bullets written by Mike Venturino.
Mike summed it up perfectly, here's what Mike wrote, directly: (am showing just the obturation-part, below)

On the flip side revolver bullets need to obturate, which means swell up. They do that in revolver chamber mouths upon firing and keep doing it upon entering the barrel forcing cone. No obturation means gas will leak by the bullet's base, melting particles off and plating them inside the barrel. Very hard bullets resist obturation and result in worse leading than milder tempered ones unless fired at very high pressure levels. Revolvers as a rule have deeper rifling so softer bullets don't skid when fired.