Thanks to all for your replies and help on this subject. I will pick up some Bon Ami on the way home tonight and we will see what transpires over the course of the next couple of days. I am thankful for a site where a question can be answered quickly by so many knowledgable people. It would take forever to reinvent the wheel as many times as I have questions.

Thanks again, and I will report on the progress.

Interesting info, Richochet, H-870 is what gave me me trouble.

Vinegar sounds less mechanically damaging than BonAmi, but . . . I wonder . . our paint contractors often use vinegar (acetic acid) to etch the surface of metals for painting, particularly galvanized items. They wipe it on and leave it, though.

Seems like anything that would physically degrade that stuff would be a tremendous help.

Zinc (the coating on galvanized steel) is a far more reactive metal than iron. That's why it protects the steel from rusting.



H870's well known for leaving a very hard fouling in the corners of the rifling grooves, especially. It's the chalk from the acid neutralization, burned to molten quicklime and depositing in the bore. Some of the other older surplus Ball powders will likely do this. (Any made before 1966 or so.)



H870's old surplus WC870, a Ball powder made by Olin (the WC stands for Western Cartridge) for 20mm ammo. Hodgdon finally sold off their supply, so there isn't any more.



I use surplus WC860 (originally loaded in .50 BMG) in my .300 Weatherby and 7mm Remington Magnums and don't encounter problem fouling with the batch I have. Mine's just a bit faster than H870, as it's supposed to be. When I use that up, I've got some WC872 already stocked up. It's slightly slower than H870; it was a 20mm replacement for WC870. They're all very close in their characteristics. With lot to lot variations their burning ranks might swap out, but Olin originally ranked the relative burning speeds of WC860, 870 and 872 at 83, 82 and 81, respectively. I've forgotten which of their powders is the 100 reference, but it's somewhere around 760.

I have some H-870 that i bought last year and have noticed
some fowling in 7mm rem mag with 175gr Hornady Interlocks at
76.0 grains but it is one the most accurate powders I've
used with the heavier for caliber bullets. Imr7828 fowls
pretty bad also, so I just clean after every 15-20 rounds
or when groups start opening up. Bore is easy to clean with
Hoppe's powder solvent and returns to shiney with tightening
of groups. Like previous poster, I like to do my cleaning at the range while the barrel is warm. When H-870 is gone
I will probably use H-1000 or IMR7828 but still clean at the
range. When I get home I like to leave my guns with a thin
coating of rig inside and out to prevent rust. I guess all
this stems from military training to keep that weapon clean
is to "stay alive"! FWIW.....