Powder switch causing leading??

[ItZaLLgooD]

Here's what I have going on. I am loading light 357's with 5.5 grains of Unique and a Lee TL 358-158 SWC lubed with 45/45/10. ACWW alloy. Just plinkers, no problems, no leading. I can shoot all day 150 -200 rounds with no issues.

I recently bought some Blue Dot to try. I loaded some up with 9 grains. Just over the starting charge. After the first cylinder I noticed that the leading had started. After the 3rd cylinder it was pretty ugly. ?? I did notice some unburnt powder after firing.

Is the increase in velocity the problem or is it the powder/pressure. I have gone up to 6.0 grains of Unique which should be pretty close to the velocity of the light charge of Blue Dot without the leading.

I am not set on using Blue Dot but I am curious why the leading.

[runfiverun]

the quicker powder is attaining a higher pressure, and it is pushing all the way down the bbl.
you have found a balance between booting the boolit and maintaining the pressure behind it down the bbl.
the blue dot just didn't get it going or have enough peak pressure [leaving the unburnt powder] across the throats into the forcing cone.
blue dot is also affected by temperature and becomes erratic below 32 F.

[fredj338]

COuld be your bullets are a bit hard & a starting charge of BD is pretty low pressure. I would bet the leading is early in the bbl??

[ItZaLLgooD]

I would bet the leading is early in the bbl??

How'd you know?


blue dot is also affected by temperature and becomes erratic below 32 F.

I knew about the temperature sensitivity but I thought it had to be colder. I mainly shoot autos but I don't like chasing brass in the snow so the wheelguns come out in winter (when it's cold).

Good thing I only bought a 1 lb jug of Blue Dot.

[bobthenailer]

I have also experinced leading & non leading with different powder loaded to the same velocity level. for me personaly unique was one of powders that caused leading.

[runfiverun]

thought i was the only one that had a love/hate with unique.
it either works for me or it don't if it does i stick with it if it don't i get away from it right quick.

[fredj338]

How'd you know?



I knew about the temperature sensitivity but I thought it had to be colder. I mainly shoot autos but I don't like chasing brass in the snow so the wheelguns come out in winter (when it's cold).

Good thing I only bought a 1 lb jug of Blue Dot.

It tells me the bullets are too hard for the low pressure & are not sealing the bore until well into the bbl. Unique is a faster powder, higher initial pressures, the bullet will bump a bit to seal the bore. That is the prevailing theory anyway.

[sqlbullet]

as others have said this is pressure related. i have experienced the same thing in my 10mm. Unique was fine, but Blue Dot leaded.

Increase the load with Blue Dot and at some point your leading will go away, or switch to a softer alloy. both worked for me.

[MtGun44]

What sqlbullet said. Unique was probably whacking the boolit harder and bumping it up, the
slower Blue Dot did not have the initial peak pressure to bump so you have an undersized
boolit, sure cause of leading. Softer alloy or faster powder. Or bigger boolit.

Also recognize that TL is a marginal lube system and is a bit less predictable than conventional
lube boolits. Works good for some folks, in some guns and some times, not so much for
other folks, guns and times. I have given up on it and have limited knowledge of LLA use,
so can't really be sure of how it behaves. Above comments are true with conventional
boolits and lubes, maybe not so much with LLA and TL designs, not certain. Not particularly
slamming LLA as much as recognizing it has some limitations and may behave a good bit
differently than conventional lube systems.

Bill

[Char-Gar]

Leading in the breech end of a sixgun barrel frequently is caused by gas cutting. This is just the gas blowing by the base of the bullets and eroding lead from the side of the bullet.

All things being equal (I am talking velocity here), the gas from faster powders were have a higher velocity and that will enable it to attack the base and sides of the bullet quicker than the gas from a slower powder)

A bullet that is too hard to expand when the pressure hits it on the base, will allow the gas to attack the base and sides. even though the bullet is a tight fit to the cylinder throat, the base is still exposed in the forcing cone of the barrel.

[Wally]

What sqlbullet said. Unique was probably whacking the boolit harder and bumping it up, the
slower Blue Dot did not have the initial peak pressure to bump so you have an undersized
boolit, sure cause of leading. Softer alloy or faster powder. Or bigger boolit.

Also recognize that TL is a marginal lube system and is a bit less predictable than conventional
lube boolits. Works good for some folks, in some guns and some times, not so much for
other folks, guns and times. I have given up on it and have limited knowledge of LLA use,
so can't really be sure of how it behaves. Above comments are true with conventional
boolits and lubes, maybe not so much with LLA and TL designs, not certain. Not particularly
slamming LLA as much as recognizing it has some limitations and may behave a good bit
differently than conventional lube systems.

Bill

Amen to that---I used a .38 Cal Lee 158 SWC-TL in a .357 Magnum at 1,100 FPS---terrible leading after 6 shots. As I have a Freechex GC maker--I found that I could gas check this bullet, as it has a bevel base. No more leading.

[MtGun44]

Wally -

Thanks for the info, not surprised at the failure of LLA and TL design at that pressure
and velocity.

Try a 358477 or 358429 or Lee 358-158-RF with NRA formula 50-50 fitted to the
throats and cast of air cooled wwts and you will be able to retire the freechex but keep
your accuracy.

Bill

[ItZaLLgooD]

Thanks guys. I would bump the charge up on the Blue Dot up but as I mentioned before these will be for winter time use here in Ohio. If Blue Dot doesn't do well in the cold I will just avoid it for the 357 and use it up in something else.

I have some HS-6 I think that I will try. It looks like it has a similiar burn rate of Blue Dot with no adverse effects in the cold. I am just looking for a middle of the road 357 for shooting pop cans without having to chase brass in the snow.

[Wally]

Wally -

Thanks for the info, not surprised at the failure of LLA and TL design at that pressure
and velocity.

Try a 358477 or 358429 or Lee 358-158-RF with NRA formula 50-50 fitted to the
throats and cast of air cooled wwts and you will be able to retire the freechex but keep
your accuracy.

Bill

Yes, you make a good point..why mess w/ a GC when you can shoot others with a plain base? I did so just to see if the GC on the Lee TL bullet would prevent the leading.

[Frank]

Powder switch causing leading? Yeah, like you're loading it more powerful and that homemade lube goes to ****. Or if you aren't using the right dimensions, Powder A will shoot Okay, but powder B exposes the weakness. A bullet that is too soft, doesn't fit and has poor design can even shoot Okay. If it fits then it is your hardness or lube. Fit, lubrication and hardness all work together. If you have the fit but are running too soft, then even with the best lubrication you will be running into problems.

[ItZaLLgooD]

Yeah, like you're loading it more powerful and that homemade lube goes to ****.

I take it your not a fan of 45/45/10:razz:

As far as fit goes, I thought that if I had no leading at first that my boolit was sized appropriately?? I am still learning about all of the factors create/cure these kind of problems.

I am thinking of getting a different mold, we'll see how this goes.

[runfiverun]

the hs-6 would be fine or just up the unique load a bit.
i shoot 7 grs of herco as my all around load in the 357 with a 158 rnfp mold, i usually keep about 2k of them on hand.

[ItZaLLgooD]

How erratic is Blue Dot in the cold? At 30-35 degrees what issues could I expect? These are going through an old S+W 66. Not necessarily the toughest 357 around.

[fecmech]

How erratic is Blue Dot in the cold? At 30-35 degrees what issues could I expect? These are going through an old S+W 66. Not necessarily the toughest 357 around.
I think the erratic in the cold thing is in regards to BD in shotshells, I've been using 9.5-10 grs of BD behind 358429 for years and never noticed anything erratic shooting outdoors in the Buffalo NY area. YMMV.

[runfiverun]

it is mostly in shotshells but it does show up in velocity variations [dips] in cartridge rounds too.
4227 does the same thing when it's hot except in the other direction.
110/296 dips in the cold.
and some rifle powders do it too.
hence the hodgdons extreme powders they are more stable [pressure and velocity wise] over a broader range of temperatures.

[ItZaLLgooD]

I think that I will try to bump up the Blue Dot charge and see what happens. Northeast Ohio is pretty similiar to the Buffalo area.