How much can you size a bullet down?

[happyhunter]

I am looking at some group buys for my 38 Spec/357 Mag. The choices are .360 and .358 inch. I just need to know is there a limit as to how small I can get if I start with .360"?

I have measured my chamber throats, next I will measure my groove diameter then I will know what my finished size must be. My throats vary a lot.... I really do not want to buy 2 molds.

Thanks,
HH

[Chicken Thief]

A pic of a .518" soft lead boolit sized to .512"
http://i295.photobucket.com/albums/mm153/Chickenthief/Skydning/Til%20andre/R0011212_zpsabde964a.jpg

Does this give you an answer?

[dragon813gt]

I've been able to get .359 down to .356. But the lube grooves allow it. That's also really pushing it. I typically size down .002 at max.

If the mold is for a 357. Just buy the .360. Unless you are looking to shoot as cast I wouldn't buy .358. I buy .358 for 9mm, not 357.

[Green Lizzard]

i size the 358 rcbs to 350 for my 348 win,in two passes with lee push through dies works good for me and the gun

[Charlie Two Tracks]

Hi HH. Can you tell us what size the throats are? You may want to get them reamed so they are closer together. Try searching on "beagling " a mold. It is a method that lets you cast larger boolits out of your mold. It can be changed back also.

[williamwaco]

sizing conventional bullets that drop at .361 down to .357 is no problem.

Microgroove bullets sized that much may completely wipe out the lube grooves.

See:

http://reloadingtips.com/pages/missing_tumble_lube_grooves.htm

for pix.

[Chicken Thief]

Btw: if the lube grooves are filled before sizing then they'll hold their integrety but the rest of the boolit will deform accordingly to accomodate the displaced lead.

[happyhunter]

Charlie,
The S&W 642 has .357 throats, the Ruger SP101 also has .357. The Ruger Blackhawk has .359. I have 2 sizer dies. One produces a .3580 to .3585 and the other produces .3595 to .3600. I have been using the smaller one for the Blackhawk, but those bullets just won't push thru the snubby throats. I think the snubbies are OK as they are; I think .357 is not too bad. Right? From what I read the groove diameter is what should determine bullet diameter. So I need to get some fishing sinkers and measure that.

The SP101 is amazingly accurate. I can't explain it, I just enjoy it. The Blackhawk is frustrating. The Rugers both have constrictions at the threads. I want to try fire lapping the Blackhawk; that is another story.

I guess my biggest concern for now is the smallest bullets I can make now are .3580 to .3585. How will that go with the .3570 throats of the 642 and SP101? I know I will have to watch for pressure signs as I work up. Anything else I need to know? Or should I just get smaller sizer die?

Thanks,
HH

[runfiverun]

get the 360 mold.
did you know you can change your alloy and get a different boolit diameter?
anyway .002 is nothing but a little more effort in pushing them through.
use a little lube it makes things easier.

[rockshooter]

also depends on the mold- I've recently bought both a Lee and a Lyman that were undersize. I'd get the .360 and hope for at least .358
Loren

[pdawg_shooter]

I am a paper patcher, I size .459 down to .451 and .311 down to .302 all the time. Works fine.

[dragon813gt]

I'd get the .360 and hope for at least .358
Loren

The OP is talking about a group buy mold from one of the custom makers. You can bet that it will drop at .360 if that's what you ordered.

[cbrick]

I have measured my chamber throats, next I will measure my groove diameter then I will know what my finished size must be. Thanks, HH


From what I read the groove diameter is what should determine bullet diameter. So I need to get some fishing sinkers and measure that. Thanks, HH

No, that isn't correct with a revolver. There is only one reason to slug a revolver bore and that is to know that groove diameter is at or a tick SMALLER than throat diameter. Size revolver boolits to a mild snug fit in the throats.

It doesn't matter in the slightest how much over throat diameter you make your boolits, when they exit the throats they will be throat diameter regardless of what the groove diameter wants/needs.

To use this mold with your two different throat diameters you need the the .360" diameter mold. To your original question you should be fine sizing to fit the smaller throats. If you get the .358" mold you will need a second mold for the .359" throats.

Rick

[rintinglen]

Normally, 2-3 thousandths is as far as I care to go, however, I have been turning 358-311 boolits that cast right at .3595 and some slightly smaller 358-429's into .348 Winchester fodder simply by sizing them once through a .355 die and then through a .351 die. Works fine and makes a great plinker. For your use, I'd size .359 and blaze away.

[MtGun44]

Like Chicken Thief said, lube them first to fill the grooves, THEN size down. The lube
will keep the grooves normal with hydraulic pressure.

Bill

[1Shirt]

Lots of variables, but I agree with MTGun and Chicken Thief on lube at larger size then resize to smaller. Trial and error process.
1Shirt!

[oldpara]

I suppose using a series of sizing dies you could size/draw a .360 dia slug down to noodle diameter.
The excessively sized bullet will lose diameter, grease groove depth, and keep getting longer with each pass I would imagine.
And lead tends to "work soften" so theres that.
At some point it would be just a longish soft lead slug.
Sizing down .002-.003, maybe more probably doesn't do any practical harm.
Get the .360.
BUT, I'm no real expert.