Anyone resized copper jacketed bullets like with Lee cast bullet sizeing dies

Lets say resizeing a copper jacketed .375 bullets to shoot through 9.3 caliber rifle

Would this produce resized copper jacketed bullets with poor accuracy???

Sizing a tough jacketed bullet down by as much as .010" would be a formidable job for something like the Lee cast bullet dies. You'd be better served with a custom made hardened die with a generous tapered lead in.

That said, you may find that the re-sized bullets will be inaccurate. The jacket and core will both size down but the jacket will tend to spring back somewhat, possibly resulting in a loose jacket. That why jacketed bullets are made by bumping up in diameter, not by swaging down.

If you only need a few bullets it might be a reasonable approach. But if it was me, I'd buy a box of the correct bullets

Ray

Reason I ask is There is a guy on another forum doing this useing 3 dies .002 resize at a time.

I didnt think it was a worth will venture when I first heard of it

I've use a Lee to take 416 down to 410. You need to put some serious pressure on the handle. I have not shot them yet so I have no comment on accuracy or downrange performance. They are bonded so I would hope they stay together. I believe Corbin suggest .004" per step.

Years ago I made some tooling to size down .308 bullets to .298 for the Terrini. Total disaster, never tried it again. roger

I have done this w/ 300gr .429" bullets to .423" for my 404jeffery. I use a .427 die then the .423 die. It works fine. Use Imperial sizing wax & as big a press as you have. Accuracy is fine for 100yd plinking, 1 1/2"-3 shot groups @ 100yds. Going from .375-.366 is quite a bump though, the jacket may want to separate.

I resize .430 44 300 gr serria power jackets to 416 with one pass. They killed things just fine out of my 416 taylor Up to 2650 fps.

I had a bunch of 311 FMJ I sized down to 308. They were moly coated, the first 5 or 6 showed scratch like lines from the die the rest went through without any signs of being thru the die.
I guess the moly coated the die.

Lyle

Someone was saying as long as the bullet does not touch the rifling, one can load larger bullets safely (working up of course). Apparently, pressure does not go up that much. Apparently too, larger bullets work well in chambers where there is a 'bit' of throat erosion and/or barrel wear. 308 Bullets down a 270 bore is over-doing it, 'though. (And yet there are 270's that have survived firing 308 Win. cartridges).

I'm not sure how much 'spring' copper has but during firing, the lead core should 'bump up' to fill the core anyway. Maybe? Distortion could be a problem during the sizing down process.

Keep us posted on your results - I want to try 8mm bullets in my 303 Brit.

quote:

Someone was saying as long as the bullet does not touch the rifling, one can load larger bullets safely (working up of course). Apparently, pressure does not go up that much. Apparently too, larger bullets work well in chambers where there is a 'bit' of throat erosion and/or barrel wear.

Not touching the rifling is a good idea under the circumstances you cite. But the real key to safely shooting oversize bullets is that the cartridge case neck MUST expand enough on firing to permit the bullet to be freely released to begin moving. This of course requires a chamber neck diameter big enough to allow the case to be easily chambered, then expand at least several thousandths of an inch when fired. I do not believe it is possible for this to happen with a properly made 9.3mm chamber if you try to shoot .375" bullets in it! However, a chamber could be made so .375" bullets could be shot from a .366" bore. But accuracy might suffer, and accuracy would no doubt be substandard if regular .366" bullets were to be used.

I size down 200 grain .338 to .329 for a surplus 8x56r. The gun doesn't shoot to good but the bore looks rough....I don't think it's the bullets. The lee sizer die does em with one pass and a fair...but not too much...effort.