Barrels Hardness

Does anyone know what the Hardness reading of most rifles. What do you use to clean the carbon out of a very dirty barrel?

Hardness will depend on the type of steel used- stainless, chrome moly, carbon, etc. The barrel mfg would have to tell you this.

Chad, have you checked the Hardness of any barrel? If so what was the reading?

After experimenting on cleaning suppressor baffles, the best I've found so far is Hoppe's Benchrest.

To clean heavy powder residue build up in a barrel, use Hoppe's Benchrest - not the old No. 9.

Saturate the bore to the point it is dripping out of the barrel.

I literally pour it into the barrel and rotate it 360 degrees to make sure it is evenly distributed.

Prop the rifle in a corner or the safe with the muzzle down in a cup to catch the liquid and leave it for 24 hours.

Put some dry patches or a paper towel in the bottom of the cup first, which helps minimize liquid spills or drips when picking it up.

Push a copper or bronze brush through it several times, more solvent, more patches.

It will come out like goop.

Repeat again for 2 - 3 times, 24 hours or at least overnight of soaking each time, until there is no more crud coming out.

Wipeout is good, but does not provide the same end result at the Hoppe's BR.

Also the Hoppe's Benchrest will not cause pitting like Barnes solvent (which is great for quickly cleaning out copper).

Used hope's No. 9 growing up as a kid. Now use a foaming bore cleaner comes in a can like shaving cream with a plastic tube on the end you jamb in the chamber and squirt till it comes out the end then let sit.

It has worked well for me and its easy. Spray it, let it sit 15 minutes brush and patch out and repeat if needed.

No, I've never paid attention to it. I know from talking to gun smith's and barrel mfg that the hardness does vary depending on the type of steel used. I know that chrome moly steel is a very hard steel, and will wear out reamers and tools quicker than stainless. My old Sako TRG 42 in 300 WM was a chrome moly steel, and it went 2200 hard rounds of 300 WM, which is pretty good barrel life. I would have to consult the barrel mfg to get precise readings on hardness. Just curious, why the interest in hardness?

Just my curiosity mostly but was wondering if Barrel Hardness has anything to do with the consistent accuracy of some brands.

Highly doubt barrel hardness is what makes accurate barrels, if that was all there was I'm sure they would all make them hard as hell.

I would bet it has much more to do with fit, finish, consistencey, set up of the equipment etc. wich would support why good barrels cost more, more labor and checking twice before cutting etc. goes into them.

Most rifle barrels are somewhere between 53 and 60 on the Rockwell "C" scale. The softer the barrel, the more easily it will foul and be harder to clean. Typical materials are 1024CM (Chrome-Moly) and 400 series stainless steel.

^^What I do.

I really don't want it 100% clean. But after the foam, and as many dry patches as it takes, sometimes 20, when they come out clean, I call it good.

I don't recall anyone ever saying they temper their barrels. What I do know is the button broach peens the rifling surface as it is forced through the bore. So the bore interior hardness will be higher than the outside surface of a broached rifle. When I was growing up there was a man that lived outside of Covington, Tx that made hammer forged barrels when he was a young man. I remember him saying that he cut the rifling into the bore and his barrels didn't last as long as "Button rifles".

I heard that Ruger used the QPQ process on some barrels. That would make the surface very hard.

I've turned a lot of barrels, most are in mid 30's on the Rockwell scale, soft. I've NEVER seen a barrel up into the 50's. The go to chrome-moly is 4140. Maybe barrels destined for full-auto are harder...

Work hardening is real. That said when cutting barrels down in the bandsaw it doesn't slow down much when the blade gets to the bore. If the bores were 53-60, you would note a discernible difference.

TDK,

Would you be more apt to believe barrels anneal, due to heat and slow cooling?

From normal shooting? No.

Tempering starts at around 350 degrees but has to be held at that temperature for a while, usually two hours. Shooting won't get hot enough.

Could you trash the gun in the process to prove me wrong, sure.

Makes sense.

I know when I'm needing to machine hard steel, that my tooling can't cut, I'll anneal. But I know I way surpass 1000°F.

You're right, it would pretty much take full auto fire, and belt fed to anneal.

Annealing is done at whatever the critical temperature is of said Grade of steel. Usually surpassing 1300f, proper annealing is done to bring the steel down to its softest state. Tempering is done at temperature ranges of around 300-600, and is done to reduce Rockwell hardness by a predetermined amount, not to reach its softest state.

In my experience barrels are mid 30's, which are pretty soft

Action bodies are low to mid 40's unless surface hardened.

Internal parts like triggers and sears are pretty hard, 55-60 for wear resistance.

TDK, is there a reason barrels are not made harder? Is it because harder metals are more prone to cracking?

Im not a metallurgist, but that would be my assumption. As you increase hardness you increase wear resistance. Unfortunately you lose elasticity and ductility, important properties for containing repeated pressure.

Knives are in the upper 50s to 60m Roclwell hardness. When working a piece of steel into a knife blade many knife makers will anneal (1000 t0 1200 degrees) the blade material to make it easier to work then temper it in an oven to get it back to the desired hardness, many guard their exact steps for getting their knives to the desired hardness.

I know an old Nickel steel Model 12 barrel didn't seem that hard when I cut it off to 22 inches with a pipe cutter.

You're using the tempering term incorrectly. Tempering does not increase hardness.

Right. Tempering will reduce both hardness and brittleness.

I'd be more interested in knowing if there is positive correlation between hardness and flexural strength. (compressive and tensile not so much) But in reality, I just buy off the shelf rifles with good reputations. It's interesting to think about which physical property would have the most effect on accuracy.