Years ago I remember reading on the label of Hoppe's #9 that you could soak the bore with the product and let it sit for 2-3 days to remove fouling from "expansion cracks." That instruction no longer appears on the label. Also, the MSDS list ammonium hydroxide as an ingredient at 1-5%. (Hoppe's #9 Bench Rest is shown at 3-7% ammonium hydroxide). I've also read that "ammonia" can damage a bore.

Out of laziness I have often just swabbed a bore with #9 after shooting and left the gun sit muzzle down for several days -- or even weeks sometimes. So, am I potentially damaging barrels with this practice? Thanks in advance.

I have tested a variety of solvents on raw 4140 polished to 400 grit over a period of several days, the metal surface showed no discernible change after exposure to Hoppe's # 9.

If that sweet nectar Hoppes No. 9 damaged bores, I would have a couple of safes full of worthless junk. Hoppes will damage nickel plating if that applies to any of your guns

Been using #9 for 50 plus years, no damage of any kind to report here....

You fine people DO know they now make a Hoppes #9 air freshener for you truck don't you? Love it....now if they'd only make a "just fired paper shell" air freshener I'd be switching out every other day.

You could fire a couple of Federal paper hull shells and put the empties in a mesh bag hanging from the rear view mirror.

Yep, I got my air freshener at the Shot Show several years ago. I've doused it a couple of times to refresh it.

When I was single, I would wear it as colongue sometimes when I went dancing. Always seemed to work on the gals, and the ones that recognized what it was were the wildest.

Ditto !!

However never used it on nickel plate....so I can't say.

Jerry

I bet I have the only wife that loves the smell of Hoppes #9. I had to switch to Montana Gold as she was wearing me out. LOL

Doc

Redeye-

You ask some thoughtful questions.

It is true that "ammonia" can damage steel. Several copper-removing bore cleaners contain ammonium hydroxide, just as does Hoppe's #9. (Sweet's is a good example.) These bore cleaners warn not to leave the cleaner in a bore more than about 15-20 minutes, before patching it out. The reason is that oxygen from the atmosphere will dissolve into the liquid of the bore cleaner. The oxygen reacts with the ammonia, producing products that can etch steel.

This does not happen with Hoppe's #9. As the MSDS sheet indicates, Hoppe's #9 is also formulated with oleic acid. This acid reacts with ammonium hydroxide, a base, to produce ammonium oleate and water. Ammonium oleate does not react with steel, but will dissolve copper.

So, there are no worries with leaving Hoppe's No. 9 in the bore for long periods.

I found the statement about expansion cracks on an old bottle of Hoppe's. I suspect that expansion cracks are a metallurgical myth. However, the advice to clean and soak over several days was probably good. Hoppe's dissolves copper relatively slowly, and getting all the copper out of a fouled bore took (and still takes) some time.

--Bob

Regarding Hoppe's #9 and nickel finish... I've used it for decades to clean many nickel handguns. It does no harm. However, that may not hold true if one soaks a part or a gun over an extended period.

I always use Hoppe's #9 on the last patch when cleaning a firearm and I leave it in the bore, sometimes for months or years. No damage.

No, but I'm pretty sure it will get you laid if you slap some on both sides of your neck, my Wife loves the way it smells.

Heat checking in the bore ("expansion cracks" by another name) in the throat area of a used barrel is a real enough phenomenon, and observable through a borescope. It is usually in a checkerboard pattern, or "alligator skin" - an array of fine cracks due to the rapid heating and cooling (and associated expansion and contraction) of the bore surface.

A long deceased LGS owner that I knew, used to open a bottle and insert a wick. Kind of like the stinky stuff from home or grocery stores, except it smelled much better. He claimed it put people into the buying mood. I suppose it worked. He sold me lots of guns.

Best,

A long deceased LGS owner that I knew, used to open a bottle and insert a wick. Kind of like the stinky stuff from home or grocery stores, except it smelled much better. He claimed it put people into the buying mood. I suppose it worked. He sold me lots of guns.

Most memorable sale from him. I walked into the shop. Owner thrust a really nice Walther PPK .22 to me. He asked if I wanted to buy a gun. Now those were hard to find and he was asking way under what it was worth. I paid him and went into the office where his son was working. He wanted to know why I was carrying his gun. I informed him that it was my gun and that I had bought it from his Dad. Obviously he had promised that piece to some really important customer as he started trying to buy it back. I finally left the store with a pristine cased Browning medalist and left another $50. I made over $600 on that deal. College for daughter got the money. Well spent!

Best,

Dan-
Thanks for your post. I've read about "expansion cracks" in another context of barrel steel, where the discussion and description was clearly fanciful. I was unaware of the term's use in connection with bore and particularly throat erosion.

Back to the books for me. (A recent Australian publication on bore erosion: [color:#0000FF]Understanding and Predicting Gun Barrel Erosion[/color].)

--Bob

Mine does too.

Not in my experience.

Rural/Country girls have known that smell since they were 3ft tall.