Gas Tube

**Clint** · 02-07-20, 13:34

Nitride might wear better, but that puts the hardness on par with the chrome lining of the gas key.

Parts are going to wear.

In many ways its better to have the easily replaceable mating part be softer and wear faster.

Would you rather have to replace a gas key or gas tube?

Originally Posted by Biggy

Does done correct nitriding the gas tube offer any practical wear longevity to the flared gas key end of a properly aligned gas tube ?

**Clint** · 02-07-20, 14:10

Mil-spec tubes are hardened.

The only way to harden 304 stainless is by working.

Spec calls for cold drawn 1/2 hard 304 stainless.

Here is a simple illustration with solid rod to convey the idea of cold drawing.

Tubing uses a more complex die to reduce both the OD and ID simultaneously.

Something more along the lines of this.

Annealed 304 Stainless steel starts out with a tensile strength of 75k psi.

The cold drawing process for gas tube stock is something like a 5 stage reduction where the raw tubing gets squeezed down longer, smaller and harder each pass.

When complete, the tubing stock has a optimized grain structure and minimum tensile strength of 150k psi.

It is a very involved and tightly controlled, high volume process to manufacture the raw tubing stock appropriate to even begin making a proper mil-spec gas tube.

Originally Posted by Biggy

Also, are mil-spec gas tubes hardened any ?

**prepare** · 02-07-20, 16:58

Clint,

Thanks for providing the extra technical details. Its pretty interesting!

**MistWolf** · 02-08-20, 06:57

Cold drawn 1/2 hard 304 stainless. No wonder gas tubes are so difficult to bend!

**Straight Shooter** · 02-08-20, 12:12

Originally Posted by Clint

Nitride might wear better, but that puts the hardness on par with the chrome lining of the gas key.

In many ways its better to have the easily replaceable mating part be softer and wear faster.

Things are going wear.

Would you rather have to replace a gas key or gas tube?

I was about to buy a nitrided gas tube for a 20" rifle Im putting together-hadnt thought about the gas key wear. Mainly wanted it for its black, non reflective surface. So, whats the answer for that with a SS tube, just painting it? Will it hold paint even?

**Straight Shooter** · 02-08-20, 12:13

double post

**AAMP84** · 02-08-20, 12:37

Originally Posted by Straight Shooter

I was about to buy a nitrided gas tube for a 20" rifle Im putting together-hadnt thought about the gas key wear. Mainly wanted it for its black, non reflective surface. So, whats the answer for that with a SS tube, just painting it? Will it hold paint even?

https://www.brownells.com/rifle-part...prod54629.aspx

**1168** · 02-08-20, 13:12

Originally Posted by Straight Shooter

I was about to buy a nitrided gas tube for a 20" rifle Im putting together-hadnt thought about the gas key wear. Mainly wanted it for its black, non reflective surface. So, whats the answer for that with a SS tube, just painting it? Will it hold paint even?

I paint them; seems to work fine.