Bullet casting diameter and weight.

[hunting99]

Hi I am new here, and to rifle reloading.

I am thinking of getting a marlin 30-30. I am thinking of casting bullets. I have read that for best results i need the bullets to be oversized slightly. So dose that mean I have to get a custom mould; or do lee make one?

Also what would be the best weight projectile for hunting.

[bladeracer]

Hi I am new here, and to rifle reloading.

I am thinking of getting a marlin 30-30. I am thinking of casting bullets. I have read that for best results i need the bullets to be oversized slightly. So dose that mean I have to get a custom mould; or do lee make one?

Also what would be the best weight projectile for hunting.

Yes, one or two thou over seems to be the optimum size.
Lee do their moulds at .309" which should work fine but you can hone it out if needed.

For hunting what game?

[hunting99]

Yes probably deer and pest control on the farm.

How do you hone the mould out?

[hunting99]

Thanks for the help.

[Gamerancher]

Lee do 150gr and 170gr molds in .309. Both are 2 cavity molds. Western Firearms has them at $39 each. Lee are about the cheapest molds you can buy but if looked after will give you good bullets and service. Get the Lee sizing die @ .309 for sizing and seating gas checks. Your lead alloy and casting temps can determine the diameter of your bullets with respect to the stated size of the mold.
As a cast bullet, you won't be able to drive these as fast as jacketed bullets even with the gas-checks, especially in a micro-groove Marlin barrel.

[Noisydad]

The reason you cant drive a cast lead bullet as fast is that at jacketed bullet speeds, the soft lead cant begin to rotate in the rifling fast enough to match the acceleration down the barrel and the rifling acts more like a wood rasp ripping lead off the side of the bullet.
The copper on a jacketed bullet is of course much harder than lead and will resist the "rasp" effect and force the bullet to rotate.
Cast bullet speeds are generally limited to about 1800 fps give or take a bit. With experience, correct lead alloy, correct bullet lube and some other considerations, around 2000 fps is achievable.

[reloader762]

I shoot both the Lee 150 & 170 gr. RNFP bullet an they have proven to be very accurate in a number of my 30 cal. rifles including my old Sav. 170 30-30 pump gun. As stated bullet diameter and weight will both be affected by the alloy used as well as casting temperature. All mold maker commercial as well as custom ones use a house alloy to spec there molds that when used will cast a bullet at the diameter and weight specified by the mold. Lyman uses Lyman #2 @15 BHN while RCBS & Lee use a 10:1 alloy @ 11 BHN. Some like Accurate molds will ask when placing an order what alloy you intend to use with that mold as well as what dia. you want you bullet to cast at.

Using a different alloy will change the as cast weight as well as the dia. +/- depending on the alloy used. Below is a chart that shows a comparison. Casting temps also affect the diameter of the bullet as hot bullets tend to shrink more especially if the lead content is high when cooling than bullet cast at the optimal temperature which is generally about 100 to 150 degrees over the melting point of the alloy,so watch those casting temperatures.



In my old Sav. 30-30 I can pretty much match factory velocity/accuracy with either of the Lee bullets gas checked,lubed and using a powder like H-335 to give it a slow gently push,other powders work just as well for any range of loads you want to work up for specific purposes form subsonic to big game loads.Bullseye for sub work and Red Dot for mild plinking loads. The 1:12 twist bore on the Savage will stabilize the 170 gr. cast bullet at factory velocity,but in many cases you can get by with much less velocity depending on the alloy your using. The Marlins with micro groove bores tend to shoot best at 1600 to 1800 fps. with bullets gas checked that fill the shallow lands and groove sized to .310" and cast at around 11 to 13 BHN. The BHN as well as the gas check is important as it helps keep the bullet from skidding on the shallow lands a grooves. I size all my 30 cal. bullets to .311" or as close as possible or powder coat them if necessary to get the dia. up to .311" My Lee molds using my alloy tend to drop bullets between .001 & .002" over the mold spec.

Below is a comparison from the Lyman Cast Bullet manual #3 that show Velocity / Expansion between factory J bullet ammo and cast loads using a Lyman #311141 bullet cast from two different BHN bullets.



I would highly recommend getting yourself a copy of the Lyman Cast Bullet Manual as it will cover all the above and more as well as give you load data for several Lee,Lyman & RCBS molds for the 30-30 along with load data you want find in standard reloading manuals.