Barrel Leading near the forcing cone end of barrel 1" down, why?

[new cal shooter]

So I was loading Red Line 158 swc .358 cast bullets, Hogdon Universal powder 4.4gr and after 30 rounds I had some moderate lead deposits about the first 1" of my barrel. Is that an indication of powder too fast or bullet too fast or bullet too slow? I was told they are very "hard" bn20 and need to be pushed fast vs slow, I was loading them in .38 spl cases so not going over 1000 fps for sure. Any FAQ for leading signs and what to avoid would be greatly appreciated. Thank you.

[tazman]

What gun are you shooting them in?

[mdi]

"Normally" leading in the beginning of the barrel indicates bullets too small and/or too hard. Did you measure the cylinder throats, groove dia. of the barrel and the OD of the bullets?

[DougGuy]

See if you can push the boolits through the cylinder throats from the front. If not, the throats are smaller than the boolits and likely sizing them down as they are fired because the boolits will come out of the cylinder at throat diameter regardless of what size you started with. Very common to ream and hone throats to .3585" to fix the problem.

[RobS]

Boolit is probably too small...........inch down the barrel the boolit seals either due to obturation or the crayon lube finally creating a seal and at that point there is no leading. The question of what your cylinder throats are in relation to your barrel's groove diameter is a valid point. I does not matter what size a boolit starts out with if it is resized too small by the cylinder throats as it exits and enters the forcing cone/barrel.

Fit is King.

[new cal shooter]

Excellent, Thank you all for the input. It is an S&W m19 6", I will try and pull down a loaded round and see what the bullet diameter is after loading, and see if an unloaded bullet will fit down the cylinder.

[new cal shooter]

leading looks like a groove in the barrel is full / dirty with lead. If you run a brass bristle brush or some stainless steel wool wrapped brush down your bore and scrub, small flakes of shiny lead come out.

[new cal shooter]

The red-line bullet mfg calls them "hard cast" and max velocity is 1200 fps, they told me Not to use mag pistol powders with their bullets. I pulled a few bullets and noticed that they were under .358". So I backed off the crimp die and now they go into the case at .358 and after loading a pulled bullet is still .358". Back to the range tonight.

I dropped a bullet tru the cylinder and 2 cylinders drop the bullet straight thru, while the other 4 hold the bullet out of the cylinder...

[Moonie]

Boolits are too small.

[runfiverun]

boolits may be too small or the revolver has a tight spot under the frame where the barrel screws in.
both are common.

[DougGuy]

I dropped a bullet tru the cylinder and 2 cylinders drop the bullet straight thru, while the other 4 hold the bullet out of the cylinder...

This is typical. Your cylinder needs throats reamed and honed. Likely the two throats the boolit drops through are the only ones delivering the boolit to the forcing cone at the same .358" diameter you are loading them. The other throats are sizing them down to whatever throat diameter is.

*IF* you drove a soft lead ball through one of the tight throats, and then started the soft lead ball at the forcing cone and pushed it into the rifling, holding a piece of paper behind the barrel and shining a bright light on it, will provide enough light that you can look through the bore at the muzzle, my bet is that you will see light coming past the lead ball where it is not sealing in the grooves of the bore because it is too small, swaged down by the tight throats.

When your hardcast boolit squeezes into the bore after being downsized by the throats, it doesn't seal either, and where light is visible past the soft lead ball, in live fire burning powder gas rushes past the sides of the boolit, melting the lead and depositing it into the barrel. Having the throats reamed to .3585" will fix the sizing problem which will fix the leading problem. Send me a PM if you are interested in having the cylinder throats sized to .3585" it is an inexpensive one-time fix that works quite well for shooting cast boolits, have many happy customers here, excellent work done.

[fredj338]

Everyone nailed this, bullets are hitting the forcing cone too small. If a .358" bullet is sticking in the cyl throat, the throat is like .0357" or even smaller. That will be the size of the bullet when it hits the forcing cone, where it bumps up after an inch or two to seal the bore. Why you see early leading. The harder bullet only makes it worse as it resists bumping at lower pressures.

[Wayne Smith]

Solution, send your cylinder to Dougguy and have him fix it.

[rintinglen]

Solution, send your cylinder to Dougguy and have him fix it.

Indeed. He did my S&W 69 cylinder for me and I couldn't be more satisfied.