cast bullet size/weight inconsistancies

[GH1]

Yesterday while loading some cast SWC for my .357, I decided to measure and weigh my bullets. After checking about six I didn't have any the weighed 158 gr, and lengths varied by .003"-.004".  I this normal for cast bullets, or do I need to find a higher quality bullet.
GH1

[Bigeasy]

Cast bullets will seldom come out the weight listed on the mold.  They vary based on the lead / tin / antimony mix being used.  I have never measured the length of my cast bullets, but I would not think an .003 / .004 difference would make any real difference in accuracy.  How do they shoot?  I have found one of the keys to consistent cast bullets is to use good, consistent technique.  Always fill the mold in one, consistent pour, and make sure there is enough over fill on the sprue plate, as the bullet will shrink a little as it first cools, and suck some of the lead back in.  Letting the mold reach proper temperature is also important to ensure it fills properly, and to avoid wrinkled or frosted bullets with possible internal voids.

Larry

[GH1]

Since heavier bullets will generate more pressure than a lighter bullet with the same powder charge, that's my main concern. I don't want to damage my gun or injure myself. Then again, I've shot 250 of these bullets with no problem so perhaps my fears are unfounded. Still, I don't like the fact that these bullets measure .357, I think switching to a .358" will help with my leading and improve accuracy.
Ayway, I was just curious as to whether or not such weight variences were normal.
GH1

[stimpylu32]

I've dropped bullets that are listed as 250g yet weigh as much as 262g , unless your pushing the ragid edge with a max load there should not be a pressure issue .

A trick that I use is to get the ave. weight of the bullet to be used , and just use the data for the bullet that is the next higher weight .

stimpy

[Flash]

You will get more pressure fluctuation from uneven case lengths than bullets cast from the same alloy. You'll always have some weight and length difference in cast bullets but there's nothing to worry about unless you're using small rifle bullets and need extreme consistancy for accuracy. The resistance on lead traveling down the barrel is tremendously less than jacketed bullets so relax, cast and enjoy.

[Sensai]

GH1, it seems that everyone has assumed that you are casting these bullets.  I don't see that in your post. The advice that you have recieved is good advice, if you're casting.  If these are purchased bullets, that opens different doors.  If you haven't slugged your barrel, and cylinders, I would recommend that you do so.  The normal recommendation for bullet sizing is .001" above groove size.  With revolvers you also have to consider the size of the throat of your cylinders.  There's a balancing act between fitting snug in the cylinder throat(s) and fitting the barrel.  There's a lot of good info on this site about that.

To answer your questions though, minor weight and length variations are acceptable for standard ammo use.  I doubt that I would accept 3 to 4 thousanths length variations in my own casts.  The fact that you have a leading problem points to undersize bullets for your gun.  There are other possibilities, but you need a measurement of your gun's critical dimensions to tell for sure.

Sorry to be so long winded, hope this helps.

[Bigeasy]

GH1

In your post you stated "Lengths varied by .003 - .004 "  Did you mean bullet diameter?  If so, then that is quite a bit.  Not enough to be dangerous with lead bullets at normal velocities, but enough to cause leading and accuracy problems.  As stated by others, most cast bullets shoot best when about .001 - .002 over grove.  I would slug the barrel and measure it.  Also, try taking an unfired bullet, and letting it drop thru an unloaded chamber in your cylinder.  It should be a snug fit coming thru the throat (front of the cylinder).  If not, you may want to try a little larger diameter bullet.  You usually get better accuracy and less leading with a bullet that fits the throat properly, even if it is .001 -.002 larger then grove diameter.  If you are casting them yourself, be sure to run the bullets thru a sizer die to maintain consistent diameter.

Larry

[GH1]

Perhaps a little clarification is in order.  These are bullets I bought, I didn't cast them myself. The varience I spoke of is in length and weight, the diameters are consistent.
In any event, I think a larger diameter bullet is in order. I'll have to slug it to determine just how much bigger to go.
Thanks for all the replies everyone.
GH1