It seems that tool marks and cast bullets just don't mix! What can one do to reduce leading when using a gun with with tool marked lands? I tried lapping the bore with polishing paste (metal glo type product) and i swabbed the bore with a ton of graphite and i coated the bore with moly spray dry lube and then i fired 8 rounds and cleaned the bore to check for leading (yes it's that bad! only 8 rounds would coat the bore with lead) oh by the way this is a .45 colt revolver and after firing the test rounds the only leading was in the forcing cone and so i thought this might work untill the lands finally smooth up from firing but when i mentioned this to a friend he said using graphite and moly together was not a good idea because one would cancel the other out in effectiveness. And he suggested some type of moly bore cream which is made by Lyman i think... any suggestions?

Not so sure it's the tool marks. Have soem pretty nasty looking barrels, negelcted from age and some WWII rough-made barrels, that shot cast bulelts just fine.

Whenever I hear leading, it thinkg of bullet diameter first. Normal would be for bullets to be sized .002" larger than jacketed (and .003" won't hurt). 45 colt is one of those calibers where slugging the bore and the cylinder is important.

Too many cylinder mouths mike .452" while the bore runs .454". So no matter what size bullet you load into the case, it will squirt out at .452" and then move into a .454" bore.

When leading is the topic, my second thought is about lube. Some lubes just work better than others, some of the commercial "hard lubes" seem to work LEAST well.

About 3rd. place is bore roughness (assumint it's not so old, eroded, pitted that it looks like a sewer pipe.

Agree with the above, and there might be a constriction under the barrel threads. Slugging will tell the tale.

Also, really, really hard bullets will lead at low pressures. What are you shooting and how fast?

Good luck!

I'm shooting cowboy loads using 250 grn bullets over 7.5 unique, 5.8 trail boss and 8 grains 800x. When the bore is really clean i can put a bore light under the forcing cone and holding a large magnifying glass over the muzzle i can see the tooling marks in the lands but the grooves are polished smoothed. Oh by the way i have tried D&J hard cast bullets as well as my own cast from WW using Lee molds in 160, 200, and 255 grains weight. I do have better accuracy with the lee bullets. Also i have not did a lot of shooting with this gun yet as i just recently purchased it. It is the gun that i posted about in the handgun section wondering about how much pressure it might be able to handle. Anyway the gun looked new (EEA bounty hunter) and when i brought it home i looked down the bore for obstructions and there was none so i went over to my loading bench and loaded a test round of only 7 grains of unique over a 250 grain bullet and then i went to the back door and picked out an old ball laying in the yard and aimed and fired at it and the bullet struck the ball dead center but the recoil felt very heavy for such a light load so i started cleaning the barrel and after about a foot high pile of patches and a few worn out bronze brushes it was finally scraped clean and i was able to see the tooling marks in the lands and so i figured the previous owner probably sold it due to the leading. Thing is though the gun looked like it had only been test fired and in fact i have already put more marks on it than it had when i got also it has what i consider to be a very low serial number.

I think Mike meant to ask how hard the bullets you are using are? With 7 grains of Unique you are in the target velocity range and should be able to fire a swaged lead bullet just fine. Hard is not necessary at those speeds and may hinder letting pressure bump the bullet up to obturate (fill and seal off) the bore from gas bypass, which causes leading. At 7.5 grains with a longer barrel, you are just getting fast enough that running something as hard as a wheel weight can help.

There are three methods used to remove lead these days, electrolytic, chemical, and mechanical. The deluxe method is the Outer's Foul Out III. It is a bit slow (a couple to four of hours or more) but is very thorough by electrolytically plating the lead from the bore onto a stainless rod suspended in the middle of it. Chemically, the Sharpshoot-R company now makes a lead solvent called No Lead that actually dissolves lead. I have some to try but haven't had a chance to yet, but it looks promising. Boretech Eliminator etches the tin and antimony out and will eventually weaken lead alloys, but I like it mainly for copper. The mechanical methods scrape the lead out. Use either a Hoppe's or a Lewis lead remover that drags a tight fitting fine bronze screen patch through the bore to scrape the lead off. The other mechanical method is to wrap a strand of pure copper scouring pad (Chore Boy, for example) around an undersized bore brush and wet it with penetrating oil or Shooters Choice Lead Remover and push it back and forth through the bore until the lead is scraped off. Just don't use a copper plated steel pad, which could scratch the bore. Test with a magnet if you are unsure, but the packaging should say 100% copper.

Several things: First, the marks on the lands are from the bore reamer. A barrel is made by first drilling a hole. The drills tend to carve out a little extra metal along the way, so they drill a few thousandths under bore diameter (except for hammer forged barrels, but I know of no handgun barrels made that way), then pull a spinning reamer through for final bore size. That's what leaves the tool marks. The grooves are then cut by a cutter, a broach, or rifling button. Those tools all follow the rifling, so they don't leave radial marks as the reamer did.

The fellows have already given you the common basic causes of leading. To elaborate a little: If the chamber throats are smaller than the groove diameter of your bore, they will neck the bullet down so it doesn't fill the bore well. Upon entry into the bore, gas pressure then bleeds around the bullet, spraying the bore with lead the hot powder plasma shaves off. The first step taken in accurizing a revolver is almost always to ream the chambers to their SAAMI maximum throat dimensions. You can get it done for about $40 here (http://www.cylindersmith.com/), but you have to send them only the cylinder itself. They won't accept a whole gun. Their turn around is less than a week if you schedule the work ahead.

Another common cause in revolvers is that the threads on the barrel are either fit or are turned into the mating threads in the frame so tightly that the throat is actually squeezed down to a narrower diameter than the rest of the bore. This has the same effect a tight throat does. It can be removed either by firelapping or by conventional manual bore lapping. If you are going to try firelapping, do it before having the cylinder reamed as you may not need to do both and don't want the lapping to further widen a bore that's been reamed to maximum diameter.

The need for either of the above procedures is determined by slugging the cleaned and lightly oiled chambers or bore with a pure lead bullet or a pure lead ball (Hornady's swaged lead ball for cap and ball guns are just fine; get one that is oversize). I start a slug into a chamber by first removing the cylinder then placing the face of it against the edge of a piece of soft pine board, then dropping the ball in from behind and tapping it into the throat with a short length of dowel. I pick the cylinder up and push it all the way through so it falls onto a soft rag or cushion then measure the OD with a thimble micrometer that has a 0.0001" scale.

I start a slug into the muzzle of a bore by tapping with a plastic headed hammer. Once it is in the muzzle, I use a brass rod to push it slowly through until it falls out the forcing cone. If there is a constriction, it will be felt to it tighten up and get slightly harder to push as it goes through the throat. Again, the slug is measured with a micrometer to ensure it is not bigger than the throats.

If the only thing you want to do is remove tool marks from the throat or rifling, you can roll some hard lead bullets in 400 grit lapping compound and just shoot them until the marks are ironed out. I do not recommend this until you know the factors are not at play, but if they are not, it will help reduce leading and make the gun easier to clean.