pressurer differences with bullet dia.

[Lloyd Smale]

heres my take on it and its not scientific. Ive shot a slug of handgun ammo some at levels that would scare a few of you. Cast bullets are soft. even hard alloys are soft compared to jacketed bullets. The only time ive noticed a slightly larger bullet cause ANY raise in pressure (determined by the old fashion pressure testing signs not with pressure testing equiptment) is when a bullet is so large that it must be physicaly pushed into the chamber. Even then the differnce in a load the shows normal pressure and one that starts to show pressure signs is minimal. Personaly i think crimp strenght can do more to change pressure in a handgun then a slight differnce in bullet size.

[wncchester]

"... when a bullet is so large that it must be physicaly pushed into the chamber."

Lloyd, I agree.  Even then I suspect the problem is more because of the bullet being squeezed in the neck rather than a difference in bullet-to-bore  diameter, per se.

One of my old P.O. Ackley books tells an of interesting experiment his students at Trinidad University's gunsmithing school once did.  IIRC, they used a Jap Arisaka 7mm to test fire cartridges with larger bullets.  They ran bullets as large as the 8mm Mauser down that bore and saw no signs of over pressure IF the throat was cut large enough to chamber them normally.  And that experiment was done with JACKETED BULLETS!