Leading and cast bevel base boolits

[Catpop]

I have ALSO been experiencing some leading in my Ruger 357 Blackhawk with cast boolits. Lately I was using OT 158 gr SWC over 5.0 grains of Unique. The leading occurred in as little as 40 rounds. I decided to load a little lower and see if that helped. Last night I loaded up 25 rounds of 3.5, 4.0, and 4.5 to see if that helped any. I will shoot them tomorrow.
Meanwhile I got to looking closely at the OT boolit's base. I then noticed it has a pronounced bevel base. From what I've read lately, I'm thinking this may be where I'm getting the leading from.
I've got some flat base boolits from a friend and plan on testing them next week.
Note: Boolits drop through cylinder with no problem so that's not an issue.
Note: barrel thoroughly cleaned of all leading between test.
What do you guys think?
Thanks in advance, Catpop

 

[mackg]

Boolits dropping through cylinder with no problem means a lack of sealing . Gases get around there and cause leading.
5 grs is a very light load; That's what I would use in a 38 (OK, it is bordering on +P then).
Depending on the bullets hardness, you might have better luck with higher pressures which would make the base expand and seal the bore.

You could also try a faster powder if economy is what you have in mind.

 

[Blue68f100]

#1 thing about shooting lead is fit. The bullet must be sized right. You want a bullet to pass as tightly as you can through the cylinder. Also the hardness of bullets helps too in determining the load. Do you have any idea of the hardness of the bullets your using.

 

[GRIZ22]

The 3 main factors affecting leading are alloy, pressure, and sizing. If alloy is too soft for the pressure it will lead. If the bullet is too large or too small it will lead.

All that said I've used 5.0 grains of Unique for years with both swaged and cast 158 swcs sized to 358 for years in a variety of different guns with no leading problems.

 

[Catpop]

Blue68f100, not sure on hardness. At least 12, maybe 14.

 

[Catpop]

Back to the original question, do you think the heavy base bevel has any bearing on this?

 

[Blue68f100]

No, I shoot the beveled base in my 45 with NO leading. I'm using the MBC 185gr SWC 12 BHN. I used to shoot the 147gr LSWC in my Python all the time. These were in the hardness range of 18 BHN. I was using 2400 back then. Again no leading. Fit is the most single item when it comes to lead. Measure your cylinder, throat and barrel so you know what size will work best and to confirm no chocking is happening before the barrel. You normally size to the throats on a Revolver. The bullet should just barely go through it, 0.0005-0.001" smaller than the cylinder.

 

[GRIZ22]

I don't think the bevel base has anything to do with your leading problem.