.38 or .357 Maximum bullet diameter
- Thread starter Rain112
- Start date
.357 Magnum and .38 spl use .357" jacketed bullets. I would start with .358" sizing at a minimum for lead bullets in these calibres. You should be able to size your bullets when you lube them with a .358" or .359" sizer.
When loading cast bullets you would usually choose a bullet 1-2 or more thousandths of an inch larger. This is for several reasons, the simplest of which is it will be more accurate and the bullet will be LESS likely to lead the barrel. Proper fit is probably the most important factor for cast bullets after lube, lead hardness, powder charge, crimp etc. Many people slug their barrel by pushing a soft lead ball through an oiled barrel to get a measure of the actual groove diameter of their barrel. If your .357 mag barrel was actually .357" I would say .358 or .359 sized lead bullets would be perfect. Some guns/calibres are known to vary more in size and it is even more important to slug and measure in these cases 7.62x54r, .303 british, .38-55 etc. As long as your round will chamber freely you probably cannot use a cast bullet that is "too" large in diameter.
If I had your mold I'd be happy with it. I would probably lube and size the bullets to .358" or .359" with a Lee push through sizer or a Star or Lyman type lube sizer. You might be able to load and shoot them as is. If they chamber ok at the larger size they will also shoot safely.
The Cast Boolits forum will have more info than you want to know, and I would also recommend Lyman Cast Bullet Handbook #4.
When loading cast bullets you would usually choose a bullet 1-2 or more thousandths of an inch larger. This is for several reasons, the simplest of which is it will be more accurate and the bullet will be LESS likely to lead the barrel. Proper fit is probably the most important factor for cast bullets after lube, lead hardness, powder charge, crimp etc. Many people slug their barrel by pushing a soft lead ball through an oiled barrel to get a measure of the actual groove diameter of their barrel. If your .357 mag barrel was actually .357" I would say .358 or .359 sized lead bullets would be perfect. Some guns/calibres are known to vary more in size and it is even more important to slug and measure in these cases 7.62x54r, .303 british, .38-55 etc. As long as your round will chamber freely you probably cannot use a cast bullet that is "too" large in diameter.
If I had your mold I'd be happy with it. I would probably lube and size the bullets to .358" or .359" with a Lee push through sizer or a Star or Lyman type lube sizer. You might be able to load and shoot them as is. If they chamber ok at the larger size they will also shoot safely.
The Cast Boolits forum will have more info than you want to know, and I would also recommend Lyman Cast Bullet Handbook #4.
easyrider604
CGN Ultra frequent flyer
- Location
- Greater Vancouver, BC
Yup. IIRC, pure lead shrinks more than alloyed lead. The more antimony and tin, the less shrinkage.
Shrinkage also depends on the lead melt temperature. Based on observation, that the hotter the lead melt, the more the shrinkage. I just keep the melt temperature high enough for clog-free pouring through my Lee 20 lb pot, around #6 on my particular thermostat.
Not Gospel truth, BTW. Many times, I have been known to draw the wrong conclusions, so YMMV.
- Location
- WMU248 near Edmonton
that mold would make nice bullets for 38 S&W 
- Location
- Ottawa origanally Muskoka
No it actually expands. After 1 week the cast bullet is both as hard and as big as its going to get. (Lead surface hardens with age)
The harder the lead alloy the more expansion will take place.
To relate a story --
I was casting some 165gr .318" dia bullets in a hard (90 brunel-aprox lynotype) and sizing with a .316" then a .314" and lubing
The next day they had grown to .316" again...so I resized to .314" a week later I went to use the gun and they wouldn't chamber. I miced one of the offending bullets to find it had grown to .3165"! Time to break out the kinetic hammer....
Also while a .002"-.004" over size bullet offers some versatility in how many different guns it can be sized to fit into. Top accuracy will come from a bullet either cast on size or sized .001" to the appropriate diameter.
My .318" to a .314" is a no no in this respect.
The more tin (Sn) and antimony (Sb) is in the mix the harder your alloy. So the hardness of say wheel weights can be increased by the addition of tin/antimony solder. You can also cast oversize by doing this. For instance a 303Brit slugged at .315" can have appropriate sized bullets cast from a .312" mold by utilizing a hard alloy in the casting process,and allowing the bullets to sit around for a week or so before sizing and loading. This practice comes at a cost however. Weight. Tin/Antimony are much less dense than Pb (lead).
Also Antimony levels exceeding aprox %6 may become too brittle for bullet use.
Increasing the tin content helps the lead flow better and a more uniform bullet to bullet casting is achieved with better mold filling characteristics.
Tin on its own will increase the hardness of lead alloys somewhat but Antimony is the real hardness increaser.
Now a harder bullet is going to hold up better under higher velocities but it will not slug up the same as a softer bullet does, nor will it expand on a game animal reliably.
Harder bullet alloys should be kept closer to bore .dia for a hard alloy sized .002" over bore dia with a stout load behind it can be detrimental to the shooters face.
This being said a bullet too conservative in dia will allow gas leakage and will result in poor accuracy and bad barrel leading, which over consecutive shots can lead to increased pressures as the over sized bullet did......
At this point I'm going to simply suggest you;
1)Slug your bore
2)Cast a conservative .001" oversize bullet
3) Use wheel weights
This is a simple starting point and one of the many bullet casting books on the market will provide you with tables, references. Tips and tricks that will allow you to advance with the practice.
Hopefully I haven't made things too complicated here for you LoL.
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- Location
- Ottawa origanally Muskoka
X2 one of many good sources on the topic. Probably the most available too.
