Mega Bore Lead

[Lost Dog]

Ok, here's the whole story boiled down. For years I had a huge stockpile of lead alloy that was given to me from a buddy that installed x-ray gear. I had several hundred pounds of it. But a couple years ago it ran out. Since then I've been trying to find suitable alloy with little effect. WW is not to be had locally. I get what I can.
The weapons that I have all suffer from extreme lead deposits in the bore.
We'll take 'em one at a time:


'09 Marlin Guide Gun. .45-70, bore is .4565". Has rust pitting in bore 4" from chamber running 5" from there (rusted from exposure to bad powder)
Loads/castings: Lyman #457124. Lee 340, Ideal #454424.(drops at .4575")
Lubes used: Lyman Ideal , NRA 50/50, Lee Liquid Allox (yuck!), Paste wax/Beeswax 40%/60% mix.
Sizing: .457", .458", .459", & unsized.
Powders used: Alliant Unique, 2400, Blue Dot, Red Dot, RX7. Accurate Arms 5744. IMR 3031.

Results: Over a 7 year period multiple attempts to access and locate a suitable load combination with the above listed items have proved problematical at best in eliminating severe lead deposits in the bore. The RX7/Lyman 457124 resulted in harsh rust formation in the bore when weapon wasn't cleaned within 7 hours of shooting. A majority of bullet sizing, powder, and lube combinations have been examined and tried in logical order by altering only one part of the loading a time. These procedures were not performed in a haphazard manner. When one aspect of the components had been exhausted, then another point was pursued. In short I didn't just jump in and change things on a whim.

As a result of the above described method, two loads stood out as having the least amount of lead forming. The Ideal 454424, a very old single cavity mould, drops the bullet at .4575". Sized with an equally old Lyman 310 sizing chamber of .457", lubed with the 40/60 paste wax/beeswax with a powder charge of 13gr of Red Dot, I achieved a significant improvement by having virtually no lead deposits in the bore. The only other load combination that came close was the Lyman 457124 lubed with the NRA 50/50 and 24gr of A5744. All other combinations were a dismal disappoint as they collectively leaded the bore.

So, armed with this information, I'm open to suggestions. Obviously the "Marlin's like fat bullets" theory falls short as both of the loads that successed were sized .457"...

 

[9.3X62AL]

A groove diameter in a 45-70 barrel of .4565" would be smaller than any I have ever slugged (total sample pop. ~25 examples). Did you slug or Cerrosafe-cast the chamber throat? its diameter is my preferred predication standard for bullet diameter.......at or .001"+ throat spec.

That rusting is a real question for me. How da h--- did a modern propellant with modern priming create THAT? Rust in grooves/lands can play hell with cast bullet accuracy, and aggravate leading tendencies. In other barrels, it has zero influence on either condition. Gotta view these on a case-by-case basis.

I'm wondering if you have access to a Lewis Lead Remover or similar system for de-leading your barrel. Chore-Boy copper fibers on a played-out bore brush does about as well. I'm thinking that a de-leaded bore followed by firing of commercial jacketed bullets might give a baseline for accuracy you could strive for with the castings.

 

[35 shooter]

You stated it's hard for you to get ww. What alloy are you using?

 

[Lost Dog]

The bore was slugged in classic fashion. Unusually small bore diameter, but none the less that is its size. The old Colt 45 Keith 255 gr SWC with 13gr of Red Dot gave me a .80" 5 shot group at 50yds off sandbags and factory open sights. That was after the pitting. Also the Lyman 457124 and IMR3031 gave similar pattern prior to the rusting, but not after, but close with A5744.


The rusting of the bore happened as follows.. 78° in the morning with 80% humidity. Shot a large hog with a cast round and moderate load of RX7. Locked and loaded another round. Didn't need it. Placed the weapon on safe and on top of the case in my vehicle in the shade with the windows down. Later in the afternoon I returned home and went to clean the weapon. Upon opening the action the chambered round I found it nearly covered in green and grey corrosion. The cast bullet was covered in grey lead oxide. Looking into the bore I witnessed a large amount of furry rust about where the rest sight was above. A dry patch came out coated in rust. Complete cleaning revealed a large amount of pitting in the bore. The primer was a new CCI LR, lube NRA 50/50, bullet 457124. The round that was in the chamber was a clean and shiny round that morning but in the afternoon it looked like it was from a museum.

 

[Lost Dog]

You stated it's hard for you to get ww. What alloy are you using?

. My brother sent me some blended WW not long ago. The other scrap lead I could get was connection buss bars from forklifts. Cleaned up of course... I have also tried some alloy from Rotometals in 20:1, 16:1 and such.

 

[Rick]

That's the first thing I thought also, bore seems a bit small. You said you tried some unsized, what did they cast at? Did you use a caliper or a micrometer to measure them? Have you done a bore slug?

Is this the same rifle that was shooting well without leading with the original X-Ray lead alloy and the only change made was a new batch of lead, your using the same load etc.? The X-Ray lead should be quite soft and there a good possibility that new lead whatever it may be is much harder. The combination of too hard for the velocity/pressure and too small can certainly cause leading.

 

[Rick]

The rusting of the bore happened as follows.. 78° in the morning with 80% humidity. Shot a large hog with a cast round and moderate load of RX7. Locked and loaded another round. Didn't need it. Placed the weapon on safe and on top of the case in my vehicle in the shade with the windows down. Later in the afternoon I returned home and went to clean the weapon. Upon opening the action the chambered round I found it nearly covered in green and grey corrosion. The cast bullet was covered in grey lead oxide. Looking into the bore I witnessed a large amount of furry rust about where the rest sight was above. A dry patch came out coated in rust. Complete cleaning revealed a large amount of pitting in the bore. The primer was a new CCI LR, lube NRA 50/50, bullet 457124. The round that was in the chamber was a clean and shiny round that morning but in the afternoon it looked like it was from a museum.

Wow that is a bummer big time. Never have I seen anything like that and the only thing I can think of at the moment is while this rifle was in the vehicle was the vehicle in a secured place? None of the components you mentioned could cause such a thing. I can't help but wonder if someone might have poured something into the bore while unattended.

.

 

[Lost Dog]

This rifle leaded up from day one. It has had 300 rounds of jacketed bullets run through it and subsequent hand lapping to smooth it out. Yes, it was slugged to obtain diameter and measured by micrometer. Further lapping to reduce the effects of pitting.

 

[Lost Dog]

Wow that is a bummer big time. Never have I seen anything like that and the only thing I can think of at the moment is while this rifle was in the vehicle was the vehicle in a secured place? None of the components you mentioned could cause such a thing. I can't help but wonder if someone might have poured something into the bore while unattended.

.

Impossible. I was 30ft from it in a remote location. It was not molested. I had fired it two days prior with a load of 3031 and it too sat in the vehicle under similar conditions. It had no rust or corrosion. I concluded that the only component that was different was the RX7. This was the newer version from overseas. The remaining amount of that went in a pile and torched.

 

[9.3X62AL]

Wow! That account of the rusting action is totally outside my experience. The only close approximation I've heard of involved a shotgun dropped into the Salton Sea and left unwashed over a weekend. I suppose black powder fouling can do similar things. Salts do NASTY things to metals, and waste no time doing so.

You are definitely swimming upstream with the totality of circumstances described herein. In your sitch, I would think hard about re-barreling or reboring. 50/70......50 Alaskan.......new custom dies, mould(s), AY CARAMBA!

I was in your spot recently, had a Win 94 with spoiled chamber in 25/35. After 3 years of palavering around, I sent it off for a re-bore to 38/55. The best $225 I ever spent on firearm work.

 

[Ian]

I'm baffled by that rusting experience. I have burned many many pounds of RX-7 old and new and never had a hint of corrosion. What you describe is like caustic fumes filling the chamber and first bit of the barrel, something I can't imagine any smokeless powder creating. Some lubes will cause corrosion over a long period of time, but I'm talking weeks to months.

Regardless, the damage is done. However, I have a few rifles with pitted bores (not dark, rotted-out sewer pipes, just a scattering of pits) and after a mild lapping to knock the crusties out have had no further issues with cast bullets. Also, I don't clean my bores so the fouling that sorta fills in the pits stays there for the long term and doesn't get disturbed by me. If you clean to bare metal and oil after every shooting session, the only permanent solution I can think of is to replace the barrel.

Bore leading is caused by one or both of two things: Deposits from gas erosion or physical abrasion, usually the first. If gas can get around the bullet before it seals (obturates) the throat, it can wash metal out and deposit it ahead of the bullet where it gets "ironed on" the bore. If the there is any lead scraped off by the sharp edge at the end of the chamber, it too can get dusted by powder gas and spread down the bore behind the bullet where the following bullet smears it down the bore and irons it on. Irregularities in groove width or groove diameter can cause gas leaks which will blast material off the bullet and leave deposits in the bore downstream of the leak. Rough spots can slough off bullet metal causing smeared deposits and gas leaks which produce even more leading. These are mostly rifle problems, some of which can be fixed by changing powder, alloy, bullet size, bullet design, seating depth, or some combination of those. A simple primer change or neck tension change can also affect how the bullet obturates the throat and cause or halt a leading condition.

Do you have a lead hardness tester of some sort?

 

[Lost Dog]

No hardness tester. Just rule of thumb(nail). Ha! Yeah, I've had people tell me there's no way a Marlin can have such a tight bore. That it's impossible to get corrosion of this scale in such a short time with this powder. Alliant refused to speak to me. Oh well.... But that's the facts as observed. I don't exaggerate as life's weird enough on its own.
But I have similar leading with a SAA Uberti clone in .357mag. But no rusting or such... Just leads up and my hottest load is 6.5gr of Unique behind a 429 in a mag case. Bore is a perfect .357" and cylinder throats are right at .358". I mean it couldn't be better. But sized to .358" Leadville first 2".... Oh well. I figured out I have to be under some curse or something.

 

[Lost Dog]

So I just shoot. Clean and scrub. And life goes on..... Now my old M&P .38 (1956 mod) leads only slightly. Like small streaks down the bore. It will clean up with a standard brush. Unlike the SAA that takes hard scrubbing. I have a Lewis lead remover from the 70's but my hand strength has left after some health issues, so it's hard to use today. I have so much lead left in my weapons that I couldn't go without cleaning like you guys do even if I wanted to!

 

[9.3X62AL]

Lost Dog.......just thought of something. Use your micrometer and measure the expander spud diameters on the die sets being used in the calibers that have guns getting leaded bores. I would be willing to bet the spuds are too undersized for the bullet diameters being seated, not expanding case mouths enough, and reducing bullet diameters during seating. This is the most common flaw in 9mm die sets; most have a .352" expander spud, and cases expanded with such tools will reduce .357"-sized castings sufficiently to cause leading and spoil accuracy. You may need fatter expander spuds for cast bullet loading--die sets these days are made with a "bias" toward jacketed bullets, esp. if that same diemaker sells jacketed bullets as part of their product line.

 

[fiver]

I have heard of the fuzzy ammo coming back out of a chamber before.
I was talking with Ranch-Dog some time back and he was having this same phenomenon happen in a rifle he was leaving loaded by the back door.
[something about Texas?]
the only thing I could think of was a vibration was making some sort of electrical jump from the rifle through the boolit and back again.

the things in common between that story and this one are the rifle brand, the use of alox, a cast boolit, and the fact they were left loaded.

 

[Lost Dog]

Excellent notion! Never thought of that. I know when I load for my .30'06 with cast rounds I use a .311 expander die in my ancient 310 tool. My cast rounds for it are sized at .309" on the Lyman 450 and .3095" with the 310 sizing chamber. And I shoot everything from little 112grGC's to 180grGC with zero lead. I think you may be onto something here!

 

[Ian]

Michael lives pretty close to the nasty, warm, stagnant bay along the coast and the wind always blows inland. I know a bunch of people in the area and everything rusts down there. To top it off that part of the country is thick with hackberry/elm/live oak forests that hold dampness and there's lots of huisache pollen in the air too, which is almost as bad for metal as the salt and constant miserable heat and humidity. You put steel, brass, and lead together in that mix and you're bound to have some issues.

 

[Lost Dog]

Fiver, you lost me with the electrical jump part.

 

[Ian]

Sort of a Faraday generator with ions transferring between the dissimilar metals as the rifle experiences frequent vibrations from the door frame.

 

[JWFilips]

Very puzzled here: I have far less experience But I have never had leaded bores or rusting in any of my guns ...shooting my cast alloy Using Ben's Red lube with a BLL overcoat so I guess I have nothing to add here except All my bullets are at least ..002 over groove dia!
& Do not clean my bores until the groups start getting BAD!