Sized vs Not Sized, Accuracy

[steve4102]

I'm casting on the cheap and using Lee molds, Lee sizing dies and 45/45/10 tumble lube.

I am working with 10mm 175gr TC and TC tumble at the moment.

From 2 of my molds (two cavity) my bullets drop at .402-.403 when sized they come out a little under .401, more like .4005.

I'm thinking about shooting (testing) these bullets as dropped and not size them. What can I expect as far as accuracy goes with these unsized bullets of varying diameter?

Thanks
Steve

[Mike / Tx]

Probably the biggest issue you will face will be whether or not they will fit the chamber well enough for reliable function.

Could be that brass differences might make one brand function well, but the next will drag and give you a jam.

That said the only other consideration is which powder your using. Some might give you a bit more pressure due to the larger bullets (ie. faster powders), where others might not. Personally I would go with a bit slower powder to start with and work up. If you see anything resembling pressure you know not to move up to a faster one.

There are plenty of folks running the Lee and other bullets straight from the molds. Most of it will simply depend on your particular chamber and ow well it accepts them.

[PawPaw]

Originally Posted by Mike / Tx

Probably the biggest issue you will face will be whether or not they will fit the chamber well enough for reliable function.

Absolutely correct.

Let's think about this for a minute. Do you think the bullet knows where it is sized? Whether it's run through a sizing die or is sized when it hits the throat? I like to run my cast bullets just a tiny bit oversized to make sure that I get a good fit in the bore. Most of the bullets I shoot in handguns (whether revolver or semi) are shot as-cast. As long as the cartridge will chamber well enough for reliable function, I don't bother with sizing.

[GP100man]

Yep ,I size em all , less for people to believe I`m not a "perfect" casting machine , so I run em thru & lube em with a quality lube to ensure fit/function !

I tumble lube less now than ever & have settled on a couple of lubes that will hold up to as much speed/pressure as the alloy I use !

But we all started somewhere & few started out with top shelf (hi dollar) equipment .

If I was start ing now I`d use RECLUSE LUBE (45% lee alox/45% johnsons floor wax/10% mineral spirits.

After lubing run em thru a lee sizer, then relube. This is how I do my wadcutters ,except there run thru a STAR sizer .

[Unclenick]

.40 S&W and 10 mm both have a SAAMI OD at the case mouth of 0.415"—0.423". As long as your finished rounds fall within that range, you should be good to go.

As-cast bullets are usually a bit harder at the surface than sized bullets. I've heard a few theories about this ranging from the mold's ability to draw heat away faster than it passes through molten bullet alloy quenching the surface harder than the core, to corruption of the crystal structure by sizing that weakens the surface over time (longer than the time it takes to shoot through a bore). There does seem to be less tendency of conventional lube groove shape as-cast bullets (just not too far oversize) to cause leading. Whether that's due to the hardness or just the better seal from a fatter bullet, I don't know. It may be some combination of the two.

I've found, where the chamber throat is right, that conventional shape bullets about 0.002" over groove diameter often lead less and are more accurate than the standard 0.001" over groove diameter bullets. 0.003" over-groove bullets are often noticeably less accurate, except that this may not apply to the tumble lube micro-bands, which I've shot larger, but not to a full conclusion on the subject. I suspect that 0.002" over groove may be a sort of sweet spot between not getting enough start pressure consistency and seal, and on the other hand not over-deforming the bullet by swaging it into the throat under pressure, which can become off-center if overdone. Of course they have to fit and feed first, and some thick brass won't accommodate that much bullet without causing a jam.

Keep in mind the purpose of the lube is not to lubricate. Lead alloys are plenty slick enough against steel to lubricate themselves for the purpose of getting down the tube. Rather, the "lube" is a release agent that stops lead blown off the base or scraped off the bullet by bore roughness from adhering to the bore. It's like a high temperature mold release. As a result, if your bore is in good condition you can often skip lubing handgun bullets altogether when the pressure and temperature are not too high (e.g., light target loads). You can also protect the bullet base from gas cutting in other ways, as with a card wad soaked in liquid lube and stuck onto the base, or with a poly-wad, or just by dipping the last sixteenth to eighth of an inch of the bullet in liquid lube. This cuts down on cost, mess, and smoke.

Folks put a lot of effort into finding the best lube, but it is really much more important at high pressures, which upset the bullet outward against the bore, raising friction and the likelihood of sticking lead to the bore. Another technique is to run a patch lightly oiled with a 100% synthetic lube down the bore every cylinder full. The right synthetics (Slip 2000 makes a good one) burn at much higher temperatures than petroleum-based products, so they don't tend to flash off or leave carbon behind. High temperature synthetic grease should be a good bullet lube for this reason, but I don't know how it is about creeping into powder an the like. Treating a bore to a 72 hour soak in Sprinco Plate+ Silver is another synthetic/moly "permanent" lube combination (actually lasts around 1000 rounds, but you can keep it replenished at cleaning time) that can make shooting unlubricated bullets work.

I will add that the Tumble Lube Lee 6-cavity mold I have for .38 wadcutters turns out bullets about 0.0025" over groove (0.3595") in my alloy, and that, fired as-cast, these are by far the most accurate shooting wadcutters I've ever used in my K-38.

[jaysouth]

There is only final authority on the subject, and that is YOUR gun.

Try it each way, keep good notes and save the targets for future reference.

Don't overthink it.