Can you size down too much ?

[Wolfdog91]

So , with the NOE sizing system letting me size very incrementally and cheaply ( like for my .30 cals I have .309.310.311.312 .313 and .315 bushings)I've been ordering molds that are a good bit over sized . For instance my Mosin slugged .313 but the new mold o just got for it is .316 as cast. Figured it's better to go big from the git go and just keep sizing down till it works. Seems like a lot less of a hassle then trying all sorts of stuff to size up an undersized bullet.
Anyhow this leads me to a question I've been wondering while looking for a mold for my .270 win.
At what point do you say , hay this is just too much to size down ? Or does it matter if you can size it down in small incriminates at a time? Like would would something like a .284 down to .277-279 be too much of a stretch ?

[leadhead]

I would think it would depend on your gun. Different bores of the same size in different rifles
will prefer different size bullets. At least they do on my rifles.

[Winger Ed.]

I'd try the different ones and see what the rifle likes.

Sizing down very much will start to smear the driving bands, but it you powder coat that shouldn't be a big deal.

[MSD MIke]

Lube grooves tend to get smaller if you size too much.

Mike

[leadhead]

Lube grooves tend to get smaller if you size too much.

Mike

Not if you hand lube them first....

[Dusty Bannister]

Sizing a cast bullet can distort the casting. It depends upon how hard the alloy is, and the type of sizer. The usual in/out lube sizers can expand the nose of the bullet making for erratic fit or bent bullets. The push through, nose first sizers like the Lee or the Star tend to not create those problems. Conventional wisdom suggests the less you have to size the bullet, the better even to the point of shooting oversized as cast if they will easily chamber.

[jsizemore]

The more you size a bullet down the more you distort it.

[stubshaft]

Short answer is YES, you can size it down too much. I generally would not size it down more than .003".

[Wayne Smith]

Think about what you are doing to the boolit when you size it. You are making it incrementally smaller in diameter, but that lead has to go somewhere. Does it go into the lube grooves, if there are any? Does it hang out at the bottom of the boolit? The way you are sizing, using the NOE push through system and doing it incrementally, this will be your major issue. When you get to the point where you have lead distorting the bottom of your boolit you've gone too far.

[fredj338]

I have gone 458 down to 452 but the driving bands start getting a bit distorted. They still shoot fine for my needs in a big bore revo but not sure about 100y accuracy.

[405grain]

I generally consider .003" the maximum that I would size down a bullet. As a rule of thumb I usually only size down .001" to .002" Though it's seat of the pants conjecture, I just feel that if I size more than .003" the accuracy potential starts to drop off. My non-scientific guess is that when the driving bands start to smear, they don't smear evenly, and that starts to create an out of balance bullet.

[Forrest r]

Short answer is YES, you can size it down too much. I generally would not size it down more than .003".

This ^^^^^^^

Any time I start sizing bullets over 3/1000th's in one pass. Bad things start to happen accuracy wise.

[243winxb]

Lyman- No more then .003"

[gwpercle]

The least amount of sizing down ... the better .
Try and get a mould that drops a boolit at the size you want or .001" larger than the diameter you want .

The least sizing ... The Better .

Buying a mould that drops .316" boolit and then sizing it down to .309" ...
you will not satisfactorly size it down .007" ... well it may be possible but involes several steps and a lot of unnecessary work ...that I don't care to do .

You can size down .001" and .002" .... and Maybe .003" on some designs but it gets real hard to size them down .004" ... you put a lot of effort and a lot of stress on press / lube-sizer .

Get a mould for every diameter change more than .002" - .003" , life will be much easier .
Gary

[MarkP]

Also depends on the initial diameter, think of it as an area reduction at constant volume. Area is proportional to the square of the diameter. So 0.003" on a larger 0.512 dia way different than say 0.003" on a 0.225 diameter.

As the diameter gets smaller the length will increase. Since the volume is constant A1 * L1 = A2 * L2 this is not entirely what happens as some material will flow into the lube grooves and not contribute to a length increase.

(A1 is initial area D1^2* 3.14/4)

Same for case mouths when necking up or necking down walls will thicken and decrease in thickness depending on necking down or necking up.

[Maven]

All, Yes, you can oversize a CB, but as already noted, you must fill the lube grooves for support. Additionally, you must do so concentrically. For example, the left hand CB in the attached pic is a Lee 323-175gr. CB whose actual diameter is .324." I reduced it to .3165" in a Lee sizing die for use in my Type 56 SKS. The CB on the right is a NOE product (C.E. Harris design) that has also been sized to .3165" for the same rifle. Ironically, the radically resized Lee CB is a tad more accurate than the NOE bullet. Lastly, such downsizing is hard on your press or lube - sizer if you use one and is certainly hard on the press mounted Lee resizing dies. Fortunately, I was able to stop when the RCBS "H & I" die and the Lee die matched (both started as .314").

[WRideout]

Seems like a lot less of a hassle then trying all sorts of stuff to size up an undersized bullet.

When I acquired my antique 32-20 revolver, I found that it liked boolits sized .313". The only mold I have for it is the Lee 30 cal 100 grain. It drops around .310-.311". I Beagled it with aluminum tape, as described elsewhere on the forum, and have been happy with the results. it isn't necessarily that hard to bring an undersized boolit up to size. BTW I cast everything big, then size down to .311" for my other pistols.

Wayne

[mehavey]

I've been sizing down the classic 45-70 cast 330 Gould to 0.452 for two years now.
(Lee push-through w/RCBS sizing lube)

The excess lead goes into the lube grooves/no base distortion.
PC'd, they shoot superbly in the (bolt) 450 Bushmaster.

[lightman]

Short answer is YES, you can size it down too much. I generally would not size it down more than .003".

My opinion exactly!

[lar45]

For revolver bullets, I've gone .458" to .452" and .412" to .404".
I like to lube first, then size down.

[JonB_in_Glencoe]

SNIP>>>
Anyhow this leads me to a question I've been wondering while looking for a mold for my .270 win.
At what point do you say , hay this is just too much to size down ? Or does it matter if you can size it down in small incriminates at a time? Like would would something like a .284 down to .277-279 be too much of a stretch ?
First I'd say, "It all depends"
and then I'd say, "I think this is a question that only you can answer for yourself"
...
12 years I started a thread about this very subject, because I read the following from page 41 of the RCBS cast bullet manual #1.

Effect of Sizing
Experience has shown that each .001" of sizing results in about an extra inch of group dispersion at 100 yards. And don't think your barrel can size any better than your sizer/lubricator. It can't. The bullets must be perfect out of the mould.
I don't necessarily agree with this statement, but RCBS found it necessary to publish it, in their book.


https://castboolits.gunloads.com/showthread.php?137277-Sizing-a-Boolit-makes-it-less-accurate

[Shopdog]

Just sayin,if your processes bend or otherwise mishapes the bullet sizing it by .001...

Then that's sizing too much.

But let's say you had a way to size down .004"(random number) and end up with a bullet that is straighter than it came from the mould... then that amount isn't too much.

So,"it depends" a lot on the processes used.

[Shopdog]

In one of your other posts,about designing a mould(IIRC).... I wrote that you should bone up on the numbers that co uses in their "prints"... think NOE. So staying with NOE,look at their prints on the depth of the lube grooves. Another way to look/reference this would be,how tall the drive bands are. Use whichever makes it more clear for this next part....

Ask yourself about "sizing"... and consider "truing" as another way of expressing this. Not saying one is a better term... saying it may help you on your path. But back to "sizing" and drive band height. What effect does sizing down .004" have on the lube groove bttm? How does this change,with a change in band height(or depths if that's how you look at it)? Saying,we're hoping the .004" loss in diameter maintained or created a straight bullet... but if it didn't,how does this effect the inner core or groove bttm diameter compared to drive band concentricity. Hope you see where I'm going. You can easily move the center of pressure radially during a large(and can happen with small) sizing. Good luck with your project.

[beagle]

Again, "it depends". .003" is the accepted norm for rifles. After that, distortion sets in especially with base first sizers. With a nose first rig, you can get away with more. I've taken .458s in steps down to .450" to use in ML sabots. This was with pure lead which makes a difference too. I've taken .458s down to .452" and .454" successfully for pistols.
Fall back to the old adage; "You don't know what you can get away with until you try."/beagle