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Did you clean all the copper fouling (from Jacketed Bullets) out of your barrel before using Cast Boolits?

Sometimes mistakes in print get carried on from one publication to another. Many US publications state that early original 44-40s have a groove diameter of .427" and later ones are .429". My own 44-40 was made in 1903 and slugs out at .429". I have also slugged and measured two original 19th century model 73 rifles and they too were .429" in groove diameter.
The question of measuring groove diameter in a barrel with an odd number of lands and grooves often comes up. What I do is to slug the barrel and then stick a piece of scrap steel in the lathe, drill it undersize and then carefully open the hole up with a boring bar until the slug will just push into it. Then measure the size of the hole.
Fred

TomH wrote:Did you clean all the copper fouling (from Jacketed Bullets) out of your barrel before using Cast Boolits?

It's had a thorough clean and de-leading.


I'm going to sort out some .430/.431 bullets and give those a go.

Well after some time away I'm back to it.

Looks like I've found the problem..... gun doesn't like hard cast bullets. Doesn't matter the size or supplier.

The .44 special were OK because they were a very soft bullet. The Magnum are copper jacketed.

I've ended up with some copper washed 245gr bullets that are all shooting straight with no signs of tumbling at all.

Thanks to all of those that helped me towards the solution..... :-)