Using Alum for Gas Checks and Alum Oxide

[tjones]

Yes the Army discovered that aluminum rods were hard on the bore....it was decided that the aluminum was soft and dirt and debris stuck to the rods like an abrasive. The 6th Army ordinance ordered their replacement with hard steel rods! -tj

[williamwaco]

I am really worried about this issue.

I don't want to wear out my bore hole.

I have noticed that all my beer cans are oxidized like crazy and I am worried what that oxide is doing to my acid reflux.

And worse, my 20 year old aluminum patio chair is so abrasive it has worn a hole in my buttocks. ( Oh wait. That hole was already there when I bought that chair. )

[Idz]

Hardness of materials in Mohs
Aluminum = 3
Copper = 3
Copper oxide = 3.5 to 4
Alumina (aluminum oxide) = 3.4
fused alumina processed with titanium oxide for grinding grit= 9

so unless you are specially processing your aluminum gas check to abrade your barrel the aluminum is less abrasive than copper checks.

[elwood4884]

Idz, thank you for this information!

[DrBill33]

As an aside: Copper also oxidizes ... as does any metal. Ever see a green copper roof? Very advanced oxidation. Neither the Cu or the Al checks that I use have ever done any damage .. my ammunition does not sit around that long!

[StrawHat]

...As a side note. One days production with all three lines running is in excess of 6 million cans. That is a lot of beer!!

Marvin...

Yeah, but how many gas checks?

[EOD3]

As an aside: Copper also oxidizes ... as does any metal.

Only a matter of time until some smart-@@@ comes along and... It may be too late already

[barnetmill]

I can remember this issue coming up 50 years ago in the Herter's catalog. Herter claimed that aluminum cleaning rods would wear the rifling out of gun barrels, so you should buy the wooden ones he sold. Of course everything in print is true to a kid, so I remember ordering a wooden .22 cleaning rod from them. Such claims are not so easily believed when whiskers are gray. I believe some artillery rounds have aluminum driving bands. Still I prefer copper of course,but if the cost difference is significant, well...

Through after all of these years I believe I still have at least one of those herters wooden cleaning rods. It seemed like a good idea at the time. Wooden cleaning rods can pick up dirt which can be abrasive so people need to keep those wooden doles clean. Even to this day I still get a big kick out of those people in what was it? Waseca, MN. I still have at least one of their presses and a lot of their dies that they sold which I really ought to replace with something better since it is not 1962 any more and I am not 18 either anymore.

[leadman]

I don't worry about alum oxide as I install the GC then coat the boolit and GC with Hi-Tek coating that is baked on.
Have you ever just fired primer down the bore and tried to clean that mess out?
I bought a pellet conversion for my 223 Rem. Shot it about 15 times total and put it in the drawer. After 3 shots the bore had to be brushed to maintain accuracy and it took many hours to get the primer residue out of the bore from 209 primers.

[PatMarlin]

Now that's a testimonial.. lol. You need a 209 primer for every pellet shot? I have never seen one. Hows that work?

[EDG]

Aluminum oxide is a fact of life if you have aluminum present.
Here is what I know about it from a practical sense.

The most common alloys that are used in high strength machined components are 6061-T6*** includes T651 and T6511
7075-T6. The most common sheet metal that I am familiar with is 5052-H32.
Then there is EC which is electrical conductor and is almost pure aluminum.

All of these oxidize (corrode) but the higher the alloyed percentage of other materials the higher the rate of oxidation.

I have seen literally thousands of tons of aluminum machined into chips making various military aircraft and semiconductor equipment parts. Most of the tooling used to cut aluminum is high speed steel since it is so soft. If you examine cutters (end mills) that have cut aluminum bar right off the rack you will find the edges worn but not notched. A cutting edge is readily notched by the abrasiveness of anodized aluminum when some rework is performed. Based on that I doubt that the very soft material used for soda and beer cans is going to harm a barrel very fast.

If some was in the high volume aluminum gas check business it would be fairly easy to treat aluminum checks so they have very little tendency to oxidize by using the common treatments from the aircraft and military design organizations.

The military treatments to prevent corrosion depend on the environment the item with be exposed to.
1. The mildest indoor environments do not require treatment.
2. Mild outdoor environment requires Chem film per MIL-C-5541 or the current commercial equivalent
3. More severe may use anodize for architectural applications.
4. The most severe will require chem film and then primer or paint. The paint may be epoxy polyamide.

A manufacturer of gas checks could get several hundred thousand treated per MIL-C-5541 in a batch for a nominal cost.
This process leaves behind a soft yellow to brown film that prevents the aluminum from oxidizing.

One of the proofs that it works is electrical in nature.
Aluminum oxide is not a conductor of electricity. Often heat sinks in electrical power supplies are anodized black so they will better radiate heat. However once the design engineer finds out the power supply does not work due to the anodize they usually change to the MIL-C-5541 coating because one version of the coating is specifically used as a low resistance coating for use in electrical applications.
I am sure that Herter's knew nothing of this coating but it has been around forever.

[PatMarlin]

I've used the very same US made, double end countersink HSS drills on my ROCKDock bases 6 years now. The same ones, and they have never needed sharpening with 6061 T6. I've used a lot of the same end mills. One very nice thing about aluminum.