Leading in .357 Magnum?

[DennisE]

Within loading manual guidelines is there a rule of thumb for what velocity to keep lead bullets below to avoid leading? Thanks, Dennis

[PA-Joe]

Generally under 800 fps using a hard cast lead alloy.

[SL1]

Leading can be caused by more than one phenomenon.

It is mostly a matter or matching the PRESSURE in the load to the STRENGTH of the lead alloy used to make the bullet. If the lead is soft (such as in soft swaged lead bullets) and the pressure is high, you will get leading. On the other hand, if the alloy is hard (such as hard-cast or heat-treated bullets), and the pressure is too LOW to make the bullet expand to fill the bore completely, then gases blowing past the bullet will melt some lead and leave in in the bore. There is some good information about matching pressure and alloy strength in Lee's "Modern Reloading" manual.

Other factors that have a major effect on leading are the initial diameter of the bullet compared to the diameter of the cylinder throats in revolvers or the chamber throats in pistols and rifles, and the type and quantity of bullet lube used.

Some reloading manuals list loads for soft swaged bullets that are restricted to the pressures (and thus velocities in THEIR gun) that will just start to lead good barrels. For instance, Speers most recent manuals do that with their swaged bullets, and provide different data for some cast lead bullets of similar weights. But, if you shoot those loads in a different barrel, you will almost certainly get different velocities, especially if your gun has a different barrel length. Trying to match the VELOCITY of the data is not a reliable way to avoid leading. Matching the CHARGE might help avoid leading. BUT, if the bullets don't properly fit YOUR gun, then you might still get leading.

SL1

[hornady]

There is a saying among bullet casters, Fit is king. In that if the bullet is under sized, you will get leading. Cast bullet must be at a minimum .001 over bore diameter, to maintain minimal leading and accuracy. And there is only one way to know the proper bullet diameter for your gun, and that is to slug the barrel and cylinder.
I have pushed cast bullets in my Dan Wesson 6 inch Barrel at around 1200 FPS, with minimal leading. But you do need to have everything right, as said bullet diameter is the number one factor. But then also in play, the right alloy mix, too hard of a bullet pushed too slow will lead, as much as a soft bullet pushed too fast, and lastly, the bullet lube must match the application used.
I have said this in other post, if thinking about casting, or shooting a lot of commercial cast bullets, buy the Lyman cast bullet manual. No one would consider reloading with out a manual, so why would you shoot cast bullets without an understanding of them.
If done properly, cast bullets can save you some real money, and be as accurate as jacketed bullets at lesser ranges, but if done improperly can cause some real problems, and I am not talking about just excessive leading.

[AlaskaMike]

Generally under 800 fps using a hard cast lead alloy.

That's an old wives' tale.

With an alloy that's at least 11 - 12 BHN, and assuming proper fit, you can drive cast bullets every bit as fast as jacketed unless there's a problem with the gun like a rough bore or groove diameter larger than throat diameter.

I routinely push plain base cast bullets using air-cooled wheel weight alloy 1300+ fps from my .357 mag and .44 mag revolvers with no leading whatsoever.

[TheGreatDane]

I recommend the Lee Modern Reloading book, as it has excellent lead-loading data.

[hornady]

Alaska not trying to start something, but you seem to be over simplifying your response, yes I will agree, I know guys that push cast bullets up around 1400 FPS, but this is nothing for the novice to attempt.also
If cast bullets could be pushed as hard and fast as jacketed. Jacketed bullets would have not been designed; Jacketed bullets were a product of smokeless powder.
Because smokeless powder can do just that, significantly increase bullet speed.
I also feel you may have exaggerated the no leading, just as you get copper fowling with jacketed bullets, you will too get leading with cast bullets, the trick is to keep it at a minumum. but also once leading starts,the more it leads and it gets bad fast.

[Scorch]

If you buy commercial cast bullets, a good rule of thumb is to keep it below 1,000 fps or so (800 fps would be good, as above). The reasons are that most commercial casters size lead bullets fairly small, and they use cheap lube. If you cast and size your own, there is an entirely different set of guidelines becasue you have control.

Sizing .001" over your bore diameter will ensure a good gas seal and eliminate gas cutting, a major source of leading. But a commercial caster may size the bullets to nominal bore diameter, which may or may not be your bore diameter, and poor accuracy and leading may result.

I recommend a premium lubricant if you intend to push your bullets fast. I used to use Lyman Orange Magic, and a friend used Rooster Red, both very good lubes. Nothing wrong with cheaper lube, it is cheaper but generally will not protect your barrel from leading as well as a better lube. But when you size and lube thousands of bullets a day commercially, the savings can really add up versus the few pennies a handloader would save.

[hornady]

I use white label lube, has done very well in rifle and pistol bullets, I use the 2500 plus for hot rifle loads and the BAC Special Blend for every thing else, both are very good lubes at a great price
WWW.Lsstuff.com

[Slamfire]

I use commercial cast bullets, Valiant told me that theirs are 13 BHM.

I got leading with Blue Dot at velocities that I had no problem with 2400 or H110/W296.

So powder makes a difference with leading. Don't know why.

Smith & Wesson M27-2 6.5” Barrel			
					
					
158 LSWC  13.5grs 2400 R-P cases Fed 100 		
4-Sep-05	T = 80 °F				
Ave Vel =	1245				
Std Dev =	22.49				 
ES  =	97.26				 
High  =	1285				 
Low  =	1187				 
N =	32				 
					
158 LSWC 13.5grs 2400 R-P cases CCI primers		
9-Oct-05	T = 64 °F				
Ave Vel =	1273				
Std Dev =	44.03				 
ES  =	176.7				 
High  =	1372				 
Low  =	1195				 
N =	30				 
					
					
158 JHP 13.0 grs AA#9 R-P cases WSP			
9-Oct-05	T = 64 °F				
Ave Vel =	1156				
Std Dev =	35.63		 		 
ES  =	160.6				 
High  =	1230				 
Low  =	1069				 
N =	20				 
Very accurate					
					
			
					
158 JHP (W/W) 14.0 grs AA#9 R-P cases WSP		
9-Oct-05	T = 64 °F				
Ave Vel =	1208				
Std Dev =	27.65			 
ES  =	89				 
High  =	1255				 
Low  =	1166				 
N =	24				 
Very accurate					
		
158 JHP (W/W) 13.5 grains 2400 R-P cases WSP	 	
5-Aug-06	T = 102 °F				
Ave Vel =	1222		 		
Std Dev =	26.45		 		 
ES  =	72.12		 		 
High  =	1262				 
Low  =	1190				
 N =	5				 
					
			
158 LRN Valiant 12.0 grs AA#9 CCI500 Mixed cases 	 	
5-Aug-06	T = 104 °F				
Ave Vel =	1278		 		
Std Dev =	34.98				 
ES  =	117.4		 	 
High  =	1344			 
Low  =	1226				
 N =	27				 
Accurate					
					
158 LRN Valiant 12.5 grs AA#9 CCI500 3-D  cases 		
5-Aug-06	T = 104 ° F				
Ave Vel =	1348		 		
Std Dev =	34.16		 	 
ES  =	134.7			 
High  =	1386				 
Low  =	1251				
 N =	25				 
Very Accurate	no leading				
		
158 LRN Valiant 13.0 grs AA#9 CCI500 3-D cases 		
5-Aug-06	T = 104 °F				
Ave Vel =	1360		 		
Std Dev =	33.19		 	 
ES  =	109.8			 
High  =	1393				 
Low  =	1284				
 N =	26				 
Very Accurate					
		
158 JHP (W/W) 13.5 grains 2400 R-P cases WSP		
5-Aug-06	T = 103 °F				
Ave Vel =	1196		 		
Std Dev =	26.58				 
ES  =	87.17				 
High  =	1244				 
Low  =	1157				
 N =	10				 
accurate					
					
158 LSWC Linotype 12.0 AA#9 Mixed cases CCI500 	
	 				
21 June 2008 T =  85 °F				
					
Ave Vel =	1166				
Std Dev =	99				
ES =	251.8				
High =	1245				
Low =	993.3				
N =	6				
					
No leading					
					
158 LSWC Linotype 15.5 W296  Zero Cases CCI500 	
	 				
21 June 2008 T =  85 °F				
					
Ave Vel =	1282				
Std Dev =	35				
ES =	128.1				
High =	1325				
Low =	1197				
N =	12				
					
No leading, no extraction issues, heavier recoil than AA#9 load		
					
					
158 LSWC Linotype  15.5 W296  3D Cases CCI500 	
	 				
14 Oct 2008 T =  80 °F				
					
Ave Vel =	1260				
Std Dev =	34				
ES =	160.5				
High =	1315				
Low =	1154				
N =	18				
					
					
158 LRN Valiant 9.0 grains Blue Dot CCI500 Midway cases 	 	
5-Aug-06	T = 102 °F				
Ave Vel =	1203		 		
Std Dev =	29.22		 		 
ES  =	120.8			 
High  =	1261				 
Low  =	1141				
 N =	22				 
leading					
		
158 LRN Valiant 10.0 grains Blue Dot CCI500 Midway cases 	 	
5-Aug-06	T = 102 °F				
Ave Vel =	1290		 		
Std Dev =	24.91		 		 
ES  =	88.15			 
High  =	1324				 
Low  =	1235				
 N =	20				 
heavy leading

[GP100man]

In MY GPs I push a PBSWC as fast as the alloy will stand or until I reach max published loads !!!

MY chambers are a consistent .3585-.359" & the bores are .3582 I size .359 & lubesize in a Lyman 450 & use White Labels Carnauba Red Lube !!

I cast with a alloy from Isotope containers which is a consistent 96/2/2 & it checks 10.5BHN, This alloy usually starts strippin/skiddin around 1200fps or so & can "tuffen" it up a little with Wheel Weights a bit if needed .

But I usually don`t , If I need more power I grab the Redhawk !!!.

I reamed the cyls. & polished the bores with Flitz on all my revolvers & this made a world of difference in the foulin left behind . Another factor is to start shootin lead with a clean bore to start with ,any copper foulin will grab a handfull of lead if present !!!

You can`t push soft swaged bullets very hard , they won`t grab the riflin & if they skid any the seal is broken & gas cuttin will lead the barrel all the way !!!