Question About Leading

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Shed

Shed

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I apologize in advance if this question sounds dumb. I'm used to shooting jacketed bullets, and have only been reloading lead bullets for a little while.

I've been working on developing a moderately hot .45 Colt cartridge for my super redhawk (SR) in .454 Casull. I took the time to slug the bore and cylinder bores, and found that the bore was around .4515 to .452 in diameter. I tested out some cartridges with .452 bullets yesterday, and their performance out of the SR was excellent both accuracy and velocity wise.

I've been very concerned about leading in my barrel however, especially after dealing with other brands of revolvers *coughUberticough*. When I shined a light down the bore after 20 shots, I noticed that the bore was still very clean except down toward the forcing cone, where I saw some dullness. I did a quick clean and some of the residue remained, making me think it may be leading in that area.

My question is, is it normal to get some leading in the bore around or directly after the forcing cone? As I said above, the remaining part of the bore was very clean (7.5" barrel). I'm going to test some .451 bullets as well to be thorough.

Thanks for the help
 
How are you measuring the throats? "Normally" leading at the cylinder end of the barrel indicated bullets too small and too hard. I size (purchase) all my cast bullets to the same diameter as the cylinder throats and have eliminated 90% of the leading with just that sizing method. What bullets are you using? Home cast or commercial? Commercial cast bullets are generally way too hard for general shooting...
 
mdi said:
How are you measuring the throats? "Normally" leading at the cylinder end of the barrel indicated bullets too small and too hard. I size (purchase) all my cast bullets to the same diameter as the cylinder throats and have eliminated 90% of the leading with just that sizing method. What bullets are you using? Home cast or commercial? Commercial cast bullets are generally way too hard for general shooting...
Click to expand...

Thanks for the input. I use #8 lead egg sinkers squeezed a bit in a vise to get them big enough for the cylinder throats.

I tried out 2 different bullets with the same powder and primers. The first were Missouri 250gr RNFP with a Brinell of 12, & SNS 250gr RNFP with a Brinell of 18. The harder SNS bullets shot significantly better groups. The amount of leading from each appeared to be the same to me.
 
I agree, more leading is caused by bullets that are too hard than too soft. I suggest shooting a bullet that rates 12BHN but no harder. Also, it doesn't sound like you are actually getting leading in your barrel. Serious leading will normally leave streaks in the barrel.
 
Fit them to the throats, not the bore (groove diameter). .457 seems large, so like the others, I would question that and want a re-measure. .454 lead is available, try it, and you may need a softer bullet, or more pressure with the ones you have.
 
Walkalong said:
Fit them to the throats, not the bore (groove diameter). .457 seems large, so like the others, I would question that and want a re-measure. .454 lead is available, try it, and you may need a softer bullet, or more pressure with the ones you have.
Click to expand...

I agree that it seems large; I re-measured my samples a few times and got readings in the .455-.457 range. I talked with the folks over at Penn and they said I should fit the bullet to the bore, and not use anything larger than that. *shrug* Thanks for the help
 
With a 12 BHN you should size the bullet 0.001"-0.002" over the bore. You have the throats large enough they will not pre size ther bullet as it passes through. The leading your getting indicates that's it not sealing off soon enough. Now if you want to push them hard the 18 BH may work better for you but you can not down load them without running into leading problems.
 
Look at it this way. When you load your revolver, the cartridge just drops into the chamber -- a loose fit. The bullet is INSIDE the case, and will be a still looser fit in the chamber. If nothing is done, it will rattle down the chamber and accuracy will go to pot.

So the chamber is in two diameters. The rear portion takes the loaded cartridge and just in front of where the bullet rests when the gun is loaded is the "throat" which reduces the size of the chamber so the bullet will be a tight fit, and controlled as it approaches the barrel. If you use a bullet that is too SMALL for the throat, the throat and forward portion of the chamber will not do their jobs. However, if the bullet is soft enough, it will slug up a bit and may fill the throat.

If I had a .452 barrel and .457 throats, I'd use a soft bullet sized to about .454.
 
.457 throats would be huge. I just googled "super redhawk 45 throat" to see if others have this problem. Based upon the response I found it seems like others are more likely to have throats smaller than normal. .450 to .451 seems like the most common problem. Did you purchase this gun new? If so I'd contact Ruger. If purchased used I'd wonder if someone has reamed the cylinder throats larger so they could use 45-70 bullets. Penn bullets has some .457 as a sizing option for their 45-70 bullets .455 might also work OK. The typical consensus for lead is size to fit the throats diameter.

I'm surprised .451 gave excellent accuracy if the throats are that large. Are you sure the measurement is correct? The bullet would have lots of wiggle room and would strike the forcing cone off center if that was the case.
 
Shed said:
I talked with the folks over at Penn and they said I should fit the bullet to the bore, and not use anything larger than that.
Click to expand...
That goes against everything I have ever read about fitting lead bullets to revolvers and leading in general. Goes against what I have done as well. You want throats that are slightly over bore (groove) diameter and fit your bullets to the throat. With throats as oversized as yours you are going to get leading if you fit them to the bore.
 
Shed said:
The harder SNS bullets shot significantly better groups. The amount of leading from each appeared to be the same to me.
Click to expand...
Shed said:
I talked with the folks over at Penn and they said I should fit the bullet to the bore,
Click to expand...
The early Lyman manual used this method, so i used it for many years. Still do. :confused:
Shed said:
is it normal to get some leading in the bore around or directly after the forcing cone?
Click to expand...
I get some, unless the alloy is hard. My home cast are sized to groove diameter or + .001" larger and work well with 38,357/.3575", .45acp/.452" and 44 mag/.430"

Near pure lead gives me more problems then (Rotometals) linotype or oven heat treated alloys, in my testing.

The worst leading i have ever seen was a Colt python 357, shooting Hornady 38s 148 lswc with 2.7 gr Bullseye . Barrel groove was .354" and bullets .358". There was no accuracy at all. Full length of barrel was fully leaded. Not my gun, so cleaning was not my problem. :D

Different firearm = Different results. As always- Do your own testing.
 
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Soft or near pure lead alloys may cause-
1. Bullet skidding.
2. Bullet slump.
3. Feeding problems in auto, nose deformed from hitting feed ranp.
4. Leading under high pressue loads, as plastic deformation occurs.
5. The sized bullet may not match the diameter marked on the H&I die. Undersize.

"Bump up" = Elastic Deformation is a change in shape of a material at low stress that is recoverable after the stress is removed . If the barrel has a tight spot (.0005") in the middle, "Bump Up" may be useful. https://www.nde-ed.org/EducationResources/CommunityCollege/Materials/Structure/deformation.htm

Plastic Deformation. When the stress is sufficient to permanently deform the metal.

In a perfect world, groove .451" , throat .452", bullet .4515" , . BHN 18. IMO.
 
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Perhaps the folks at Penn were thinking about rifle bullets? All the revolvers I own have throats in the cylinder and not bored straight through so there is not much correlation between case size and chamber/throat diameter.

Basically, if the bullets are smaller than the throats, gas will leak passed the bullet, causing melting and leading. If the bullets are bigger than the throats, they will be sized down as they pass through. Normally the cylinder throats are just a few thousandths larger than the groove diameter of the barrel, so a bullet exiting the throat will be just a few thousandths larger than the groove diameter, insuring a good fit/seal. Hard bullets normally don't obturate enough (bump up) to seal the throats and/or the barrel, and too soft will often "skid" on the rifling. For a general use alloy I prefer 11-13 BHN and for some applications Lyman #2 (around 15)...
 
Can too small hard bullets in the cylinder throats be related to gas cutting? I was told that gas cutting caused this leading in the rear portion of the barrel. Leading up front indicated lube failure. Leading all up and down meant too soft an alloy. I was told not to get lead wash and leading confused.
 
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As long as the bullet will pass through the cylinder throats your good. It's the forcing cone that should be doing the sizing. Too small in the barrel will cause leading no matter what the hardness is. Some powders that run hot can cause issues too. These normally have a high nitro content.
 
Mowgli Terry said:
Can too small hard bullets in the cylinder throats be related to gas cutting? I was told that gas cutting caused this leading in the rear portion of the barrel. Leading up front indicated lube failure. Leading all up and down meant too soft an alloy. I was told not to get lead wash and leading confused.
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You betcha!

Gas squirts past too small bullets, and the increased pressure at that point results in gas cutting. Similarly, bullets that are too hard for the pressure and velocity of the load will fail to obturate, with the same results.
 
Vern Humphrey said:
You betcha!

Gas squirts past too small bullets, and the increased pressure at that point results in gas cutting. Similarly, bullets that are too hard for the pressure and velocity of the load will fail to obturate, with the same results.
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^^^^ What Vern said.:)
Plus, I can't see how those beveled bases on a lot of commercially cast bullets (that are way too hard to start with) help the bullets obturate one darn bit.o_O
 
The bevelled bases make them easier to load. Since I keep lead loads mild to moderate, and use jackets for hot loads, this has never caused me any problems.
 
Shed said:
bore was still very clean except down toward the forcing cone, where I saw some dullness. I did a quick clean and some of the residue remained, making me think it may be leading in that area.

... is it normal to get some leading in the bore around or directly after the forcing cone?
Click to expand...
Excerpts from Glen Fryxell's ebook Chapter 7: Leading - http://www.lasc.us/Fryxell_Book_Chapter_7_Leading.htm

"Definition of leading. Leading is the deposition of significant amounts of bullet metal on the bore. It can take many forms -- streaks, chunks, splotches, films, etc. ... Nor is a gray "haze" on the bore surface necessarily a problem; it can be an indication of a leading problem, but it can also be simply a reflection of the alloy of barrel steel used, how the rifling was cut, or a reflection that the barrel isn't "broken in" yet.

Forcing cone. Leading found in the forcing cone proper can be the result of the cast bullet being significantly over-sized relative to groove diameter and being swaged down as it enters the forcing cone. It can also be due to the forcing cone being poorly or roughly cut, or cut off-center (it does happen...). Or it can be due to poor cylinder timing leaving the chamber(s) in poor alignment with the barrel at ignition. This last case will generally have an asymmetric build up on one side or the other, and the revolver will commonly 'spit lead'.

Immediately in front of the forcing cone. If the leading is observed immediately in front of the forcing cone, then it's almost always due to a constriction in the barrel caused by an overly tight barrel/frame thread. This is most readily diagnosed by slugging the bore, and feeling for added resistance as the slug passes through this portion of the bore. Fire-lapping will usually clean this up pretty quickly and effectively. Hand-lapping requires more knowledge and experience, but allows the shooter to feel when the job is done and results in a more uniform bore surface throughout the length of the barrel."
 
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My opinion is Ruger has a bad habit of oversizing their cylinder throats, my Redhawk in 44 mag has .434" throats. I cannot not shoot a lead bullet from this gun without leading, I have tried dozens of cast bullets of various diameters up to .432" and BHN at all different velocities.
My S&W 696 does not lead with the proper BHN for the pressure, the throats on the 696 are on the + side of .429"
 
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