Might advances in 3-D printing might soon make it really possible to make working guns?

There have been a real problem with using 3-D printing to make guns, the barrel of the gun hasn't been able to withstand the pressure from the explosion of the bullet.  If 3-D printing can make parts that can withstand the explosive pressure of a rocket engine, might they be able to withstand the explosive pressure of a gun?  From QZ.com:

Even if 3-D printing doesn’t change the economy, it has the potential to change manufacturing—making it cheaper and capable of producing better parts and products.  

Now the NASA space agency and Aerojet Rocketdyne say they have successfully tested a rocket engine injector that was made using powerful lasers to “melt and fuse fine metallic powders into three-dimensional structures”—read, 3-D printing. . . .  

According to the engineers behind the project, the test results matter because, unlike a lot of the basic structures created by 3-D printing, the components inside rocket engines must be machined to extremely exacting standards. If they can withstand the heat and pressure of burning rocket fuel while maintaining high performance, it’s a sign that the techniques behind 3-D printing can have major applications in all kinds of machining scenarios. . . .