Severe Barrel Leading

[rcmodel]

Out of round by .002" to .004" is certainly not helping anything at all.
It wil cause gas cutting past the bullet.

Check your unloaded bullets for roundness.

Check your sized cases for roundness before loading them.

Check your cases after seating, but before crimping.

You could have a cracked carbide ring in the sizing die.
You could have a bullet seating stem that doesn't fit the bullet causing crooked seating.
You could have a defective crimping die.

Just some things to look at and rule out.

rc

 

[sigman2]

I just measured three bullets and it looks like they're running .0005" to .001" out-of-round.

I will be visiting my dad in the New Orleans area for the next week or so. I'll continue this when I return.

Thanks to all

 

[blarby]

We'll see ya when you get back !

 

[Arkansas Paul]

Leading is caused by trying to drive a cast bullet too fast or excessively soft bullets.

That is 2 things that can cause leading.
However I would bet money that more leading is caused by a bullet being too hard than too soft. At least in handgun applications.

Keith used a mixture of 16-1 lead/tin giving his alloy a BHN of about 11, which is softer than the OP. And the loads the OP used aren't in the same ballpark as the insanely hot stuff Keith loaded.

Low velocity and hard bullets don't go together. Many people who don't have a lot of actual hands on experience with cast boolits think that a harder bullet is the solution to most leading problems when in actuality it is the cause of many of them.

 

[Walkalong]

Leading is caused by trying to drive a cast bullet too fast or excessively soft bullets.

There is more to it than that.

Undersized bullets, unless they have enough pressure to bump up and fill the bore, will cause gas cutting and leading when the hot, high velocity gases "cut" lead off the bullet on its way between the bullet and the throat and/or barrel. Leading will be mostly at the throats and forcing cone, but will continue until it fills the whole barrel if you keep shooting the offending load.

Properly sized bullets (in the range of .001 to .002 over throat diameter) will not suffer from gas cutting unless they are too hard.

Bullets that are too hard will not bump up and seal the throats and barrel well, even when sized properly, causing leading.

Bullets that are too soft to hold the rifling at the velocity they are driven at, will break loose from the rifling and "skid", breaking the seal and causing leading galore all the way down the bore.

If the bullets are sized properly, you can get away with them being a little harder than needed.

If the bullets are soft enough to bump up easily with the pressure used, you can often get away with them being a hair undersized, as long as they are hard enough to hold the rifling for the trip down the bore.

Hmm....did I miss anything? Probably.

 

[LiveLife]

Leading is caused by trying to drive a cast bullet too fast or excessively soft bullets.

However I would bet money that more leading is caused by a bullet being too hard than too soft. At least in handgun applications.

If the bullets are soft enough to bump up easily with the pressure used, you can often get away with them being a hair undersized

+1. Nobody complains about 22LR lead bullets being too soft to cause leading in pistols or rifles regardless of velocity.

When 18 BHN Missouri 200 gr SWC (IDP #1) bullet leaded the oversized Taurus PT145 barrel full length with my usually 5.0 gr W231/HP-38, the solution came from softer 12 BHN Missouri 200 gr SWC (Bullseye #1) bullet. Bullet-to-barrel fit and .001" over groove diameter mantra? No, I didn't want to have two different diameter lead loads for my 45 pistols. I am a firm believer of "Hardness-Optimized" MBC bullets.

Even with the lighter 4.0 gr charge of Red Dot/Promo, 12 BHN bullet base undergo enough plastic deformation/expands sufficiently to seal with the oversized barrel to not lead the barrel while producing accuracy.