Anybody resizing the 7.62x39 bullets to .309?

[Zippidydoodah]

Anybody resizing the .312's to .309 and shooting in 308, 30-06? Didn't know if they would lead the bore or ok to shoot that way.

[Ranch Dog]

Anybody resizing the .312's to .309 and shooting in 308, 30-06? Didn't know if they would lead the bore or ok to shoot that way.

I'm not sure if the bullet features would hold up. What happens during resizing; whether by die or barrel bore, is that the lead will flow to the area available in the lube grooves. The grooves simply disappear and you are left with a solid bullet. If the bullet is lubed before sizing, the lube will be displaced as the lead is a solid.

[mikld]

Some cast bullets with deeper lube grooves may hold up vs. tumble lube style grooves, but .003" isn't very much to size. Otherwise I agree with Ranch Dog...

[Zippidydoodah]

What happens to the rest of the bullet that is left over after filling the rifling? It has to be displaced too. And Lee states you can shoot their tumble-lubed bullets without resizing. Isn't there more lead than groove. As long as there is adequate lubrication you shouldn't get leading(within reason) or is there as much rifling width as lead to fill it out? I think more.lead.

[Zippidydoodah]

I don't have that die anyway but wondered if it could be done or if Itcan be done, how? I guess speed would be a factor, bullet alloy, whether it has any alox coating on it,etc.

[Ranch Dog]

Some cast bullets with deeper lube grooves may hold up vs. tumble lube style grooves.

From a design standpoint, there is no difference between a standard lube groove and Micro Band in depth. Same with catching material in sizing. The spacing of standard groove is greater so they have more material available to fill the grooves. The spacing of the Micro Band is less so there is less material being pushed into the groove.

What happens to the rest of the bullet that is left over after filling the rifling? It has to be displaced too.

Not quite sure what you mean by this question. it is the last word, "rifling" that throws me. One thing that happens at the shot that isn't happening during sizing is compression, compression of the alloy under extreme pressure. It doesn't flow anywhere but is compressed to form what is molding it. That is why bullet fit is so darn important.

And Lee states you can shoot their tumble-lubed bullets without resizing.

Yes you can up to a point. The "fins" formed by the outer edge of the bands offer less resistance and less physical deformation to the structure of the bullet.

Isn't there more lead than groove.

Sorry...

As long as there is adequate lubrication you shouldn't get leading(within reason) or is there as much rifling width as lead to fill it out? I think more.lead.

This is a subject with a lot of components as it not just about the lube. Alloy and its strength is what withstands the pressure you place behind the bullet. That is why a swaged lead bullet doesn't have or need lube grooves. The design uses the right alloy for the intended cartridge and the swaging takes all the "give" out of the alloy. The bullet is hard enough to withstand the intended pressures without obturation and is as effective an alloy as copper for the given cartridge.

This might only be me but my work with a wide range of bullets and cartridges over the last decade and a half has formed so thoughts in my head that at times differ from the old school thinking. One such though is that lube acts only as a temporary seal while the bullet obiturates to the bore. I simply do not think that a lube seal can resist a pressure that etches it way past the base of a bullet that has been obtiturated to the bore under pressure. My evidence supporting this is the perfect wax stars seen at the muzzle yet the leading along the rifling. If the alloy isn't tough enough, no amount or type of lube, is going to see that alloy survive. Where survival is determined, initially, is at the throat, leade, and step as start pressures forms the bullet to these features. Lube acts as a temporary seal here but not a very good one if the bullet isn't designed to match these feature.

Back to the topic subject. If I wanted to avoid a huge amount of sizing and retain the design features of the mold, I would smoke the heck out of the cavities. The results will probably surprise you if done correctly and evenly. I just addressed this in your topic: Spray graphite on mold?

[Zippidydoodah]

Thanks for the explanation. Did you "invent" the micro lube grooves used on the Lee molds? I think I can spot some of your bullet designs used by Lee -wide meplats,RFs, and thank you for always explaining our rambling questions. It seems the lead bullet design is more an art because of all the factors you have to work with. Jacketed probably has half the factors to consider. Thanks for your work.!

[Ranch Dog]

Did you "invent" the micro lube grooves used on the Lee molds?

No, Mr. Lee did that work. If anything, I'm known for bringing Micro-Bands to rifle bullets and then using them at jacketed bullet velocities and pressure for the intended cartridges.

[Zippidydoodah]

Thanks, do you always size em or shoot em as is?

[Ranch Dog]

Thanks, do you always size em or shoot em as is?

I size all my bullets... at least once. My gas check bullet get a pass through the sizer before lubing as I want the checks on a base free of lube. I have also had the unseated check come off when the pulled is removed from the cookie sheets I set them on to dry. The next pass through the sizer is used to remove the excess lube.