Cast boolit diameter

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SSN Vet

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I recently purchased a new mold (Lee TL358-158-SWC) to cast this boolit from 75% WWs / 25% pure Pb.....

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My boolits are measuring .359" on one axis & .360" on the other (slightly out of round) on the bottom driving band and .358" on the TL grooves.

I will be shooting these from a 6-1/2" .357 mag revolver, which I attempted to slug tonight. But the barrel has 5 grooves, so I can't measure the dia. straight across. I played around with rotating the boolit in the caliper and also dropped the boolit into a drill index and attempted to measure the play in a 23/64" drill index (coming up with ~.356" to .357"), but can't say that's an accurate number.

How can I read my slug, without a hole gage set?

Do you think these boolits are safe to test fire with a modest load (3.7 gr W231) in a 38 spl case?
 
SSN Vet,

Typically with revolvers, the cylinder throats are the more critical dimension for the proper sizing of cast bullets. You will need a pin/ball gauge to measure them properly. How will you be sizing your bullets?

Don
 
:) Vet you're Good to Go.

Vet, with Lee's Tumble Lube Bullets you are ok shooting them "as cast".
You do need to pick up a bottle of "Lee Liquid Alox", and pan lube your bullets per Lee instructions.

Your bullet design, with the multi "fins" are made to shoot as cast-they need not be sized/lubed with a lubersizer.

Now, don't get me wrong--these tumble lubed loads WILL smoke!!!Bill.:)
 
Do you think these boolits are safe to test fire with a modest load
Yes.
They are also safe to fire with heavy loads.

Bullet & bore diameter is a non-issue as far as safety of loads is concerned.

If it will fit in the chamber, the chamber throat & forcing cone in the barrel will make it the right diameter for the bore.

Thats why they are called Forcing Cones.

rc
 
Great! I was hoping so, as I loaded 25 @ 3.7 gr. and 25 @ 3.4 gr. last night.....

All of my pistol boolit molds are the TL style and I pan lube with either LLA or Rooster.

I only cast one rifle caliber, and I pan lube those.
 
I use the same mould/bullet.

I do size my bullets to .358" with the push-through Lee sizer.
I get slightly better accuracy this way.

How accurate? I had to reshoot for qualification in NRA PPC as they changed the classification system last year. (Service and Match Gun classifications).
I shot a 480/35x (480/48x possible) on my first run using the Lee .358TL over 3.1gr of Bullseye which correlates to the 3.4gr of #231/HP38. Firearm is a S&W Perf. Ctr "reworked" Mod 14 with a 4" heavy bbl. With above listed loads it is near 1-hole at 25yds.... Ditto a Zero or Precison Delta 158gr swaged SWC

I believe sizeing the bullet "trues" them up so that accuracy is improved. Also, with some brass, an un-sized bullet will expand the case to the point that they may not chamber in some guns... Biggest reason to "size" the bullets before loading.
 
You size to prevent leading.

If you slug your bore, measure the groove size of it, and match it with a bullet that is just slightly larger, you decrease gas cutting. Bullet hardness, velocity, phase of the moon, and the way the wind is blowing seems to also contribute toward leading.

Cast bullets can be fickle. But they are fun.
 
Safe? Yes. Variations of the amount of antimony in an alloys will produce different bullet diameter as they drop from the mould. Tin, not so much. This also effects bullet hardness. The pressure/ zero will change between batches. This is why we size bullets.
 
Load a few & try em as cast .

As goose said If they`ll chamber your good ,the throat of the cyl. will make em round for the bore!

Your alloy should be in the 10-12bhn so it`s not super hard & just by the act of seating may take care of any parting lines on the boolit.
 
Sizing to prevent leading???

Umm, no. Sizing only induces leading. Sizing, by definition, reduces bullet diameter. You do not prevent leading, ever, by reducing bullet diameter.

The purpose of sizing is to make a bullet fit a particular firearm. We use the largest size that fits to prevent leading.
 
If the bullet is out of round, sizing it will help prevent leading due to gas cutting around the edges. So yes, size to fit prevents leading.

Lyman Cast Bullet Handbook Page 52 states: "It is always better to shoot a round bullet than one that might have even minor out-of-roundness." Reading further, one deduces that the reason being is that an out of round bullet doesn't completely fit the bore and can have gas cut up the sides, thus causing leading.
 
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Cast bullets are designed to be cast slightly over the diameter needed, then lubed/sized to the correct size, which will also round them nicely since lead and lead alloys have little to no spring back. This can result is a very accurate bullet which does not lead, assuming the alloy is correct for the pressure/velocity, and is lubed properly. I have tried bullets as cast and properly sized, and in general the properly sized bullets shot better.
 
Leading is frequently due to a mild load that fails to bump undersize bullets up to obturation. It seems to be "conventional wisdom" these days to have cast bullets 2 or even 3 thou over groove diameter but there's absolutely nothing to gain by doing that. No matter what excess diameter a bullet has it will be corrected by the time it fully enters the bore but a barrel is NOT a good, consistant sizer. Starting at or very close to groove diameter is a good thing.

Any tiny 'out of round' hand gun bullet hardly matters to a full bore size (or larger) projectile so long as the smallest point is the same or more than the groove diameter.
 
SSN Vet, That's the boolit I shoot.

I used to size them with a a Lee .358 kit, I don't even bother anymore. I shoot them as they drop after a light coat of Lee Alox. I just squirt a bit and shake 'em around in a plastic bin.

Mine are more accurate when sized, but not enough to justify the time for range blasting ammo.

I recently got the 6 cavity mold for the same boolit. I'm very happy with it. Highly recommended!

I do get some leading, a few minutes with a copper scrub pad around a brush cleans the bore and cylinder up nicely.

Good Luck
 
If the bullet is out of round, sizing it will help prevent leading due to gas cutting around the edges. So yes, size to fit prevents leading.

No, sizing an out of round bullet makes the uneven gap around the bullet bigger. So gas cutting increases if the bullet is undersized. The OP's bullet is oversized and there will not be any gas cutting because it will swage down in the cylinder throat.

As far as accuracy goes, what's the difference if the bullet is sized down by a sizer die or the cylinder throat? The difference, if any, will be due to combustion, pressure, velocity, etc resulting from the smaller bullet and not due to a .001" difference in roundness.
 
As far as accuracy goes, what's the difference if the bullet is sized down by a sizer die or the cylinder throat? The difference, if any, will be due to combustion, pressure, velocity, etc resulting from the smaller bullet and not due to a .001" difference in roundness.

Yup! Nothing like shootin lopsided bullets even tho it's only .001 and at the RPM's they spin I'm sure they'll get downrange-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Somewhere!



Maybe!
 
You people don't understand that an out of round bullet will obturate and conform to the bore and thereby become perfectly round when it leaves the muzzle. That's why Lee TL bullets are successfully deployed as cast.
 
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