"How much will a bullet bump up?"

[TAWILDCATT]

I just expanded a .402 bullet to .420 in a vise.now if it was lubed why cant it be put in a die and bumped up.

[montana_charlie]

Excellent question. If somebody starts a thread about using oversize dies in heavy-duty lubrisizers, to swage bullets into a new design, you should ask it.

[wonderwolf]

I'm not having any trouble bumping up a .360 pure lead slug to .410 and .429 in my swage dies. granted its a short .60" long but I can try it with a much longer pure lead slug when some core molds arrive from RRR.

I've often wondered if even with some of the shorter 45 cal bullets (in the 400-450gr range) if they all bump uniformly throughout. Everything I read and look at gives me one answer or another.

One thing though I'm guessing is the amount of time that the pressure is applied to the bullet itself has something to say about it being bumped up in a bbl vs anything we do with a vise or swage dies. In bumping a bullet up in size in a swage die that takes a few seconds vs. a bullet traveling down a 30" bbl at 1400 FPS or whatnot.....

From a physics standpoint now that I think about it would the pressure from a swage die or a vise be from two directions, Bullet nose and tail? Where in a firearm the bullet is getting the pressure at the tail end and relatively little pressure at the nose end? Thus the "shock wave" of the exploding black powder charge would bump up the bullet at the base first and move up the body of the bullet?(think minie balls and how the skirts blew out and stayed flared out maybe?)....Would a dry (unlubed) patched bullet then bump up better since it offers more resistance to this tail end pressure (or is that just relative?)?

[243winxb]

Lee wants the pressure below where Obturation would happen. http://www.realguns.com/archives/118.htmCompare the pressure listed here for Obturation to take place.http://en.wikipedia.org/wiki/ObturateIf a cast lead alloy bullet Obturates, it will deform and break down, leading the barrel. The structure of the bullet will be changed when jumping for the cylinder to the forcing come. Not so much change will take place in a auto fixed chamber firearm. Bullet's BHN x 1422 = Pounds per square inch.
According to the chart, a very popular #2 alloy carries a 16 BHN, has a strength indictor of 22,703 PSI and should be limited to 20,000 PSI as maximum pressure. Wheel weight alloy with a BHN of 9 carries a strength of 12,748 PSI and a MAX pressure rating of 11,473 PSI The paper patch fills the void/diameter between the alloy bullet and the bore.

[leftiye]

243, I really liked that approach several years ago. But as person after person here reported outstanding results with high pressures, and softer than expected boolits, it becomes obvious that softer boolits will shoot accurately regardless (not an absolute statement, it doesn't always shoot well. Bad news is - nothing does) of pressure level, and sometimes higher pressures shoot better. The trick lies in making your boolit fit the leade and throat in your chamber. If the boolit is supported when the pressure is applied, the boolit doesn't deform and can still shoot accurately. I have to agree with the obturation not being desired part though, as (especially in revolters) gas seal is critical to stopping leading, and this is accomplished by pushing a slightly (+.001") oversize boolit into the chamber mouth or leade.