Pressure Rings on Flat Based Bullets

[Max]

Just curious. Is the pressure ring at the base of flat based bullets a by-product of manufacturing or is it purposely put there to act as a pressure seal when the bullet enters the barrel?

 

[BoydAllen]

It is a useful byproduct. Factory FBs have it ironed down so that they can be more easily used with automatic loading machinery....or so I read.

 

[lpreddick]

the bullet pressure ring...ah yes. i'v had some interesting experiences with these things. many years ago berger offered a 25 cal 110 gr mef flat based bullet...i still have some. the pressure ring measured .001 greater than bearing surface on the bullet and if seated below the neck/shoulder juncture, the bullet would fall into the case! most rings now measure .0005 greater than bearing surface. the tightest contact between a flat based bullet and the case neck is at this ring. i tried neck sizing half a 22 br case neck and seat the bullet BELOW the sized neck thinking the ring would now be below the neck constriction and the bearing surface would now have more contact. didn't work as i hoped. the ring dilates the neck and it did not "spring" back to grip the bullet and i could push it deeper into the case thereby preventing me from seating into the lands. tried grinding the ring off but too much work...sometimes i have too much idle time on my hands. boat tails don't seem to have these rings and i suspect bullet/case contact is more uniform.

 

[BoydAllen]

Generally, I find it a bad idea to have bases of flat base bullets seated below the sized portion of necks, and take the view that this is a die, rather than a bullet issue. I would agree about the effect of pressure rings on neck tension and bullet grip, but with the pressure ring within the sized portion of the neck, I have not had any problems. One of my better bullets has a rather large pressure ring, and it shoots very well. I have also observed differences in tune, based on using different bushing sizes.

 

[Shynloco]

Generally, I find it a bad idea to have bases of flat base bullets seated below the sized portion of necks

In every book written by the tops shooters and experts that I've read and some I've spoken to, STRONGLY say that is a NO NO or seating deeper than the neck/shoulder junction with an FB bullet.

Alex

 

[Max]

Thanks for your input guys, it's always good to hear different points of view.