Sciencemadness Discussion Board

What acid will dissolve copper/brass but not chromoly steel?

drycan - 19-1-2011 at 15:02

Guys i need a bit of help from the experts here. I got a 380 live round stuck inside a chromoly steel container with no way to get it out. The round is composed of brass casing/primer, copper bullet jacket and lead bullet base. I need to dissolve this thing if possible without damaging the chromoly steel. Only thing i found is Nitric acid?

not_important - 19-1-2011 at 16:11

Nitric of the proper concentration __might__ leave the steel alone, passivating it. However the passivisation is often destroyed by contact with metals below iron (coppper n this case) so it's not certain it would work.

Strong aqueous ammonia plus reasonably concentrated hydrogen peroxide could work, both Cu and Zn forming complexes with NH3 while the H2O oxidises the elemental copper.

Mercury will dissolve zinc and copper (more slowly) while it doesn't amalgamate with iron; can't say what it would do to the alloying metals in the steel. It would take multiple refillings to get enough of the brass to dissolve, so it's not an easy fix for the problem.

In either case I think that lead will be untouched, and may prove difficult to dissolve without attacking the steel. BTW chromoly or 41xx steel is not much more corrosion resistant than other common steels, so it's likely to be attacked by most things that might dissolve the brass.

drycan - 19-1-2011 at 17:48

Thats not good news at all. I am not worried about lead, i can get the lead part out, i mainly need to get rid of brass

ScienceSquirrel - 19-1-2011 at 17:56

Acid is not going to work.
You are going to have to resort to cutting and drilling.
A good gunsmith should be able to do it.

inspector5 - 19-1-2011 at 18:15

I have a couple of questions. First, are you sure the bullet is lead and that it's not copper jacketed? If you can remove the bullet, then the powder, are you able to access the rear (primer) side of the case? Also, may I ask what exactly the round is stuck in? If you don't wish to answer the last one directly, could you give some general info about the "container" such as OD, distance from end to each side of the round, etc?

drycan - 19-1-2011 at 18:37

yeah it all comes down to cutting it open i am afraid, as i knew all along but wanted to exhaust all options. its inside a rifle supressor, rattles in there between the baffles and is next to impossible to get out

inspector5 - 19-1-2011 at 18:43

Do you have access to a VERY isolated location?

drycan - 19-1-2011 at 20:29

yeah national forrest is my backyard i can drive in a middle of nowhere and not see a person for miles

inspector5 - 19-1-2011 at 21:23

It would take a while but if you can get somewhere you can absolutely certain noone else would be and you can both dig a hole and start a controlled fire that also has some sort of natural shelter you can retreat to but not be to far in case when the round discharges you can be ready, with a fire extinguisher handy, in case some hot embers are ejected, you could go out, dig a deep (18-24" or about .5 m) and long (3-4' or about 1 m) trench, fill the trench about 1/4 of the way with good dry wood, lay the suppressor at one end, then put more wood to bring level up to halfway and start the fire at opposite end and let it burn. Once the round discharges you should be able to use a pin punch and a hammer and probably all the patience you have to wiggle it around til it's line up and hit it and eventually you'll get the now-empty case to where it will come out.

Really just depends on whether the suppressor is worth the PITA.

Edit: The suppressor will need to be re-blued bit the ting you're done.

[Edited on 20-1-2011 by inspector5]

drycan - 19-1-2011 at 21:27

inspector5, a round thats not encased inside a tight chamber is of no danger. You can throw a buch of rounds inside a fire and all they will do is go "pop" and the bullet might travel a few feet. I was thinking of just putting it inside the oven till it pops but i dont know if thats going to be any more difficult to extract all the brass peaces...

smuv - 19-1-2011 at 22:16

In that case, couldn't you heat the suppressor with an oxy-acetylene tourch and melt the lead/copper out? Lucky for you, 4xx series steels fare a lot better at high temps than more chemically resistant 3xx series.

[Edited on 1-20-2011 by smuv]

Eclectic - 19-1-2011 at 23:23

Ammonium nitrate and/or acetate and peroxide might attack the lead as well as the copper and brass....experiment and see.

ScienceSquirrel - 20-1-2011 at 03:10

If think the best thing would be to take it to a gunsmith.
He would probably work it round and wiggle it out.

drycan - 20-1-2011 at 11:04

i am cutting it open, chemistry takes too much dicking around

hissingnoise - 20-1-2011 at 11:47

Having a gunsmith check it out seems the sensible thing, as SS suggested!

Paddywhacker - 20-1-2011 at 11:53

Ammonia and hydrogen peroxide will eat into the copper in brass, and probably the zinc too. Rather slowly, though.

cyanureeves - 20-1-2011 at 14:40

Quote: Originally posted by drycan  
inspector5, a round thats not encased inside a tight chamber is of no danger. You can throw a buch of rounds inside a fire and all they will do is go "pop" and the bullet might travel a few feet. I was thinking of just putting it inside the oven till it pops but i dont know if thats going to be any more difficult to extract all the brass peaces...
drycan are you sure? that sounds very ,very dangerous.anyway brass melts alot quicker than steel,cant you reach the bullet with a torch flame?

inspector5 - 20-1-2011 at 16:28

Quote: Originally posted by drycan  
inspector5, a round thats not encased inside a tight chamber is of no danger. You can throw a buch of rounds inside a fire and all they will do is go "pop" and the bullet might travel a few feet. I was thinking of just putting it inside the oven till it pops but i dont know if thats going to be any more difficult to extract all the brass peaces...


@drycan: You are correct that an unsupported case is no danger but a tight chamber is not required for the projectile to be released at a dangerous velocity. If the case is partially supported by the internals of the suppressor in just the right places the brass's modified (by the partial support) yield strength maybe more than the crimp pressure+bullet's inertia and that could be very, very bad.

@smuv: taking a torch flame to a live round with your hand (and the rest of your body) nearby seems like a bad idea. Also, chrome-moly is 41xx alloy steel not 4xx series stainless.

@everyone acting like taking it to a gunsmith is the only sensible idea: While it definitely would be less work, so would be buying nitric acid instead of distilling it, or buying sulfuric instead of the lead chamber thing axehandle did, or buying MMO anodes, etc, ad nauseam. All of those things are also dangerous in some way, especially if done in a reckless manner, as is just about everything on this site but that doesn't seem to have stopped anyone.

drycan - 20-1-2011 at 21:09

inspector5, i can assure you that if the round cooks off the round wont be much harm. the velocity is reached via powder being burned inside the rifle/pistol barrel, in our case the brass case would rupture and the bullet might go 30 or 40 feet. the only danger would be flying brass that might get in your eye or something.

White Yeti - 16-8-2011 at 12:03

A mix of glacial acetic acid and 30% hydrogen peroxide could eat through the brass without destroying the steel.