Cerrosafe - another question

[ghh3rd]

I would like to know if Cerrosafe can be used to accurately slug one's barrel. I know that it changes shape (shrinks) after it is poured, but have read that the measurent would be reliable if taken 1 hour after pouring it.

Has anyone had any good results with Cerrosafe for slugging?

Thanks,

Randy

[BABore]

Nope!. Tried it on several different barrels. Even after waiting the required 1 hour, I come up with different dimensions than those from a bore slug or upset slug in the throat. How do I know which one is right you ask? I cut cherry's, then molds, based off of those dimensions. I then measure the cast boolits and compare them to my bbl/throat data. The Cerrosafe readings always seem to run big which results in a loose boolit fit. I'll stick with using a soft, hollow, egg sinker for the bbl and a pure lead cylinder upset in the throat.

[ghh3rd]

When slugging, is it necessary to pass the slug through the entire barrel?

[Sensai]

Actually, when you use Cerrosafe, it's casting or making a cast of your barrel. It serves the same purpose as slugging the barrel, which is driving a slug of slightly larger size down the barrel.

I have been making casts of barrels and chambers with Cerrosafe for over thirty years and have never had a problem getting good data. It shrinks for about a half hour after pouring, then returns to original deminsions an hour after pouring. That's when you want to take your measurments, one hour after pouring. This has never been advertised as a permanent cast of the item you casted, so don't expect the deminsions to be accurate if you go back and take a measurment of it next week or next month. I think that's where some people are having problems. If you need a permanent cast, then a cabon and sulpher or epoxy cast will serve the purpose better than Cerrosafe, but it takes more preperation and more than a little practice.

The beautiful thing about Cerrosafe is that if you don't like the cast, you can make another in about ten minutes.

[BABore]

When slugging, is it necessary to pass the slug through the entire barrel?

It all depends what your looking for. The last thing a cast boolit see's is the muzzle end, so that's nice to know. Some bbls that have dovetail cuts, heavy roll marking, or tight receiver threads may have bbl constrictions. It doesn't do a cast boolit much good to be sized down by a bbl constriction, then rattle the rest of the way down the bbl. A bbl may also have some wear just ahead of the throat for a short distance. A boolit sized to 0.001 to 0.002 over the smallest point in the bbl may be sloppy in the beginning, giving it a chance to yaw some.

When I'm serious about making a gun shoot, and I'm going to make a custom boolit to fit it, I want to know it all. I do a muzzle slug, then another that is pushed all the way through. They are compared to see if firelapping is justified or not. How the bbl fouls or leads will also affect this decision. Next, an unsized, lead filled case is chambered, an undersized lead cylinder is slid down the bore, and it is upset to fill the throat and a short portion of the rifling. Finally, a once fired case, from a full powered load, is measured to determine chamber neck dimensions. From this I can determine best boolit fit, which is;

- Sized to just slip fit into the fired case and be just above groove size.

- Fill the throat.

- Engrave into the bore lightly.

This gives the boolit three point contact, or very close to it, so that it can only go straight out of the case and into the barrel. Given a decent, constriction free bbl, and good crown, yoiu can do almost no wrong.