^^^ This.........Barrel leading mainly is caused, and can be alleivated, by adjusting two two things: Projectile hardness and projectile speed. The harder the projectile, the faster it can be pushed.
^^^ ...and this...I'll also add proper bullet size to the bore. Cast bullets should be .001 bigger than the bore diameter. If they are smaller gasses can get between the bullet and bore causing leading also. This isn't usually such a big deal on modern guns because they are usually consistent.
...also this, However, it's unlikely that the boolit is made from pure linotype. It's just "too hard" if that's even a good way to say it! ;-)Also not sure if anyone mentioned it but linotype is just a type of lead made to a certain hardness. It has it's name because it's what's used in linotype machine which are a type of printing press. If you ever come across lead in thin strips with letters, numbers or words on the edge that's linotype. it's suitable for all magnum pistol and rifle cast bullets. It's around 22 BHN.
^^^ Summed up nicely. There are plenty of casters who make lead rounds for rifles and push them at typical rifle speeds without leading up their barrels. I think that if you're shooting lead boolits, you should definitely check the barrel after a couple hundred rounds to see if you have leading. Or check after every 20 rounds. whatever makes you more comfortable.Regarding cast lead, I would think if the bullets are decent hardness and right diameter you can push em pretty hard. I pushed cast bullets pretty hard in 44 Mag and .45 Colt without any leading using H110. Great hunting loads.
Also, shooting jacketed rounds behind lead rounds does NOT "clean" lead out of your barrels. It mostly just packs it into the grooves even more tightly and makes it harder to clean out.
You mentioned using gas checks which is a pretty good idea if you want that last bit of extra insurance. It can help if you simply can't get everything else just right and accuracy or leading is still an issue for a particular firearm.
Note that a good, correct lube or in some cases, a good coating is a critical point as well.
Back to the hardness of the bullet. They can be TOO hard, depending on the myriad of other details. If the boolit is too hard, it won't obturate completely in the barrel and can allow gases to get past the boolit and, of course, create leading. Sometimes, a softer boolit (of the correct diameter) is going to perform better at many points.
Regardless, the right combination of factors is needed:
- Proper size. Most critical
- Proper hardness
- Proper velocity
- Proper lubrication
Keep this in context. Without it, that list sounds like advice to a young man on his wedding night.