Confused about leading - Revisited

[pat g]

Confused about leading

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I am new to casting bullets so I have a lot to learn and this is the place that I have found the best location to learn.

Here is the question: I casted 44 mag bullets 200 gr. rnfp.
The bullet size was 431. A 429 sized bullet dropped right through the cylinder.
The bullets were tumble lubed with alox, and sat for 48 hours befor being loaded.

I tested the bullet at about 15 bhn. I loaded 7.8 gr. of Unique. ( Light Load ).
I started low because I am learning and would not like to make a mistake.

The bullets were fired from a Ruger Super Blackhawk.

After shooting about 30 rounds I cleaned the gun and there was very heavy leading. The lead came out in strips.

I believe there is a vast amount of knowledge on this site and Lord knows
I could use some help.

Thanks
Pat

The barrel is 428 and the cylinder is 430.

I took the advise of wiser sages and increased the Unique to 9 grs.
The leading was reduced to about a quarter of what it was.

I am now going to try the 45-45-10 lube and see what the outcme is.
If this does not work I will be forced to buy a luber sizer.
I have trying to avoid buying it because I have a small fortune already into this reloading.
Three (3) presses, dies, powder, measure and on and on.

Pat

[BABore]

The groove diameter sounds small for a Ruger. How did you slug it? I'm assuming that you pounded one pure lead slug all the way through. Did you do a second slug just into the muzzle and then back out? Did you feel a tight spot when your slug passed under the bbl threads? Where does the leading start in the bbl?

I have a gut feeling that you have a bore constriction. While I'm not a fan of liquid lubes, I've never had them lead the bbl like that unless I did something really stupid.

[462]

As BABore mentioned, the location of the leading is a very useful diagnostic tool.

[captaint]

From what we know at this point, I'd have to go with barrel thread restriction. What are you measuring your barrel slug with?? Calipers, micrometer?? It will matter.. enjoy Mike

[Multigunner]

Not saying its a common situation, but I was once asked to testfire a Ruger .357 double action revolver, don't remember its model designation, and watched as the bullets, .38 specials this time not magnums thankfully, came out spining sideways through the air to hit the clay bank about as hard as if shot from a wrist rocket sling shot.

The bore was leaded worse than any I've even seen. After cleaning it I found hundreds of concentric striations on the lands and some cutting down as far as the bottom of the grooves.
Best I can guess it a chip caught in intial drilling out of the bore, and a long and inexplicable run of workmen not noticing while the barrel went through the rest of the manufacturing process. I should have had that barrel sectioned and kept as the example of the absolute worst quality control foul up in history.

I'd have the bore examined by a competent gunsmith, and lapped if it needs it.

I don't know what method Ruger uses to rifle its barrels but I've seen sectioned button rifled bores that showed striations that were ironed out in the process so that they offered no friction it one direction, but cut through bullet jackets like a file if the finished barrel had the edges turned back towards the breech.
Button rifling can't iron out a poorly bored and reamed bore surface.

[Larry Gibson]

Let me mention that since '68 I've shot tons of .429 sized cast bullets (my own and commercial) through numerous .44s in cluding a few Rugers. I had nothing but good accuracy and no leading provided i washed off the hard wax commercial lube and relubed with Javelina. Perhaps I didn't get the 'best" accuracy but back when my eyes were youngs and the sights were clear and sharp a 1" 5 shot group at 25 yards was the goal and was often met. Granted I these days shoot .430 or .431 sized bullets along with a lot of commercial .429 also. I've never "lapped" a revolver barrel yet.

With that in mind et me suggest that the 7.5 gr charge of Unique is alright for the shorter .44 Special case but is way to low a load for the magnum. If you insist on Unique bump up to 10 gr (Lyman lists 11 gr as a starting load for a 200 gr cast bullet) and work up to 13 gr. Also, you don't mention the alloy. BHN means nothing if the alloy is too rich in antimony. What is happening is the gas is blowing by the undersized bullet in the cylinder throats causing gas cutting and probably blowing off the lube too. Suggest cutting the alloy with a little lead (20 - 30%), switching to Bullseye ( I use 6 gr under the same type 200 gr bullet for a pleasant and accurate load), and leaving the bullets "as cast" at .431. One last thing is to Lube the bullets liberalyy if you are going to push up with Unique. You might want to get a .431 Lee sizer (or hone out the .429 you've got) to finish the lubed bullets with.

By doing such you will have a better fiting bullet to the cylinder throats, the softer alloy will obturate with the hotter Unique or Bullseye load, the gas will not blow by the bullet gas cutting the lead and blowing it into the barrel to be deposited as leading, the lube will be sufficient to do the job and you will be a much happier camper.

Larry Gibson

[pat g]

I am not married to Unique I will try another powder.

I will load it with a heavier charge, about the middle of the spectrum.

I felt no tight spots in the bbl., when I slugged the bbl.
It seems very consistant at 428.
I used a micrometer to measure the slug.

I am also going to try a heavier slug (240 gr.)

Thanks

Pat

[pat g]

Went up to 11.2 unique the leading problem is gone.

Why does heavier load cause less leading?

Thanks

Pat

[RobS]

The higher charge/higher pressures may very well keep the slug obturated the entire length of the barrel reducing or eliminating gas blowby and leading.

[geargnasher]

Bingo, RobS.

Gear

[btroj]

Rob s is right, your increase in pressure may have improved your fit.