Decreasing bullet weight

[Arlin]

Gentelmen/ladies:

Just received my new147 grain 9mm mold. It casts a 154 grain bullet. How do I change my mixture to get the weight down to 147?

Arlin

[Ola]

hmmm... Why?

[fredj338]

More tin. What is your current alloy, what mold? My RCBS throws cww alloy about 148gr.

[Arlin]

Why do I want the 147 grain bullet to weigh 147 grains, My current loading data for Tightgroup powder does not have loading data above 147 grains. I can, and probably will find a diferent powder to work with the heaver bullet if I have to.

The alloy is clip on wheel weights with a BHN ~13. I am using a new Lyman 4 cavity mold. The mold is advertized to be 356 dia but is actually 355 as cast. Both the heavy weight and undersized bullet gave me a little heart burn.

[Ola]

My current loading data for Tightgroup powder does not have loading data above 147 grains. I can, and probably will find a diferent powder to work with the heaver bullet if I have to. Or then you could just ignore the weight difference and use the listed minimum charge (or little smaller). And work it up from there. That is what I would do..

After you have tried it out and if there is a problem with the diameter, then add some tin as said.

[runfiverun]

the weight won't be your problem the undersize and length are the issues.
the diameter you can fix yourself, either through lapping or an alloy change.

[popper]

What does your bbl slug and what alloy is the mould spec'd for? Any room left for powder? Beagling or lapping will increase the weight. I think LASC has a chart for alloy vs size (shrinkage). If the mould isn't right, get Lyman to correct it - the only way they will learn. If the CB is too long, the fix is to machine off the top of the blocks.

[Springfield]

From 147 to 154 grains is only a 1/2 % increase in weight. Just use the specs and stop being such a worry wart. Differences in alloy and diameter will make far more difference than that small weight increase. ALWAYS start low and work up.

[popper]

5% difference

[Bullet Caster]

.0454545454545454545454545454545455, to be exact. BC

[Larry Gibson]

Add 2 % tin to the COWWs.

Larry Gibson

[fryboy]

tin and antimony both add mass with less weight than lead does ( ie; both are lighter than lead and both adds to the overall cast dimensions slightly ) most molds are supposedly cut for lyman's #2 alloy ( 5/5/90 tin/antimony/lead ) using a alloy with more lead and less of the other two will make a casting heavier and smaller , using more antimony or tin will make the casting fatter and lighter
not all molds drop as advertised ...simple fact , i have a mold that states 180 grains yet even with #2 alloy i get 200 grain castings [shrugz] a few grains is usually no biggie as long as we start small and work safely up

[stubshaft]

Just remember that as you lose weight, you increase diameter.

[PbHurler]

Just remember that as you lose weight, you increase diameter.

Funny?; My Body operates on Direct Proportion :bigsmyl2:

[Arlin]

Gentelmen:

Thanks for all your responses. I'll get some tin and see what difference it will make. I found an old reloading manual that gives me a load for 158 grain bullets for the 9mm using Unique. I've loaded a few rounds and will try them out today. I'll post my results if I have fingers left.

Arlin

[41 mag fan]

Just remember that as you lose weight, you increase diameter.


Man....that post made me think of food and I just gained another 5lbs. [smilie=1: