Home Forums Hunting & Shooting Gunsmithing Galvanic action btween Rifle and posts

Is anyone experiencing any reactions between the aluminum/SS posts/pillars and the rifles action/

I have wondered about this junction of dissimilar metals.

I saw a 16mm film on the galvanic series in 8th grade shop in 1964.

I bid some military contracts in the 1980s that had MIL-STD-889 dissimilar metals requirements.

In 1984 I build the world's fasted filling big bathtub. I had galvanized and brass adaptors in series to get 1/2" and 3/4" copper pipe connected to ball valves that looked like 1/2" or 3/4" holes. But every time I turned on the water the first gallon of water was all rusty. I had to take it apart and make it without the steel parts.

So I had no excuse when I put some brass pillars in rifles in 2002. Later I realized my barrelled action was a sacrificial anode.

I am now not afraid to put Aluminum pillars in rifles, and let the pillars be sacrificial while protecting my barrelled action.

My pillar bedding has a fine layer of bedding on it. The receiver does not come in contact with the pillars.

Galvanic corrosion is not possible without an electrolyte like salty water being present. Mere contact between the action and pillar is insufficient.

RAN
.

In many A-Borts made back about the mid-'90s and for quite a few years the long wire trigger links would rust and sieze almost overnight in Kodiak weather... a little salt spray is all it takes.

It's been a while since general chemistry. What makes one metal sacrificial in what circumstance?

The term used is nobility. The circumstance doesn’t change, just where in the hierarchy the materials exist.

Actually circumstances can change such as the different places held by some metals depending on the availability of oxygen.

Ok

If you can't lose them with logic then baffle them with bullchit.

Are you suggesting you do not know why there are a number of different alloys holding more than one place on the nobility chart? Or worse you have no clue such a thing exists, yet want to snipe?

So, does this mean Prince Harry is more or less likely to rust now since he left the Royals Club?

Sorry, this stuff just pops up in me. Actually an interesting subject.

He is already rusty, check his hair, duh!

off topic but interesting-- the process of bringing life back to the dead using electrical current is also called galvanizing and was the theme of the Frankenstein novel. Maybe thats what happened to Prince Harry.

Chemistry part, its the electromotive potential between elements that cause electron migration and "coating". How much depends on the formula of the steel, Fe/Cr/. On the periodic chart anything to the right of an element can give up electrons to any element to the left. If a strong oxidizing or reducing agent is also present the "flow" of electrons can be increased or decreased , O2, sulfuric acid etc.

Cadmium cadmium can also be used in place of Zn, but is special purpose. "Nickel" plated cartridge cases were really cadmium plated, until it was found out that the toxic effects were cumulative similar to mercury, lead.

Anybody who has owned aluminum bodied cars with steel frames can relate to this. I could tell you horror stories about a certain '66 Land Rover whose aluminum body rotted from the bottom up, even with a thin buffer of felt between body and frame. Then there was my BIL who shimmed a scope base with a piece of soda can- the giveaway was the rust we saw creeping out from under the base.

Had severe cancer on my 1959 Austin Healey 100-6 where the felt had worn through.

Interesting thread that explains a lot. More than once I've been out hunting and had a rifle or shotgun fall into pieces, showing corrosion at the edges. Probably partly due to my compulsive cleaning at dissimilar metal contact points which kept the ccontact points chemically clean.

some type of ionic solution must be present, salt is a good example, but anything that has dipoles as opposed to non-polar solvents (oils example), can cause "migration" and coating.

a "dirty" gun would have some oils left in the grime, and as long as it broke up the polar solvent, the "battery" effect would be stopped.

the metals "coating" the Fe and preventing iron rust are really the oxides of that metal, ZnO, zinc oxide, aluminum oxide etc. and are only on the surface of that metal, are very hard, and prevent the oxidation of the Fe

The polar salts do not have to be NaCl but can come from primer mixtures. Lead styphanate, sodium nitrate others, military surplus contained large amounts in the primers, and that is why military barrels had a reputation for corrosion and the subsequent "need" to have them chrome lined. Because the residue was so "polar" ordinary solvents wouldn't work thus the need for a hot water flush.