Is there that much of a difference in quality between these 2 steel barrels?I have read a few articles online that have said 4140 is very good quality and not that far behind 4150. Does anyone have any helpful comments or links on this subject?

SAE, society of automotive engineers, labels ChromeMoly steels by using the 41xx designation. The final two numbers are determined by how many points of carbon are present in the alloy. One percent carbon content overall would be one hundered points of carbon. This is true for all SAE labels. Thus 1095 is a simple carbon steel of .95% carbon content. 1040 steel has a carbon content of .40%.

The higher carbon steels are more easily and extremely hardened. But, as a whole they can become brittle. This should not be a problem you would ever encounter with an ar.

But, I have seen hand made 1095 steel blades hardened and heat treated which were then abused. The result, tips of knives were snapped off. This upsets both the owner and the artist who made the blade.

Both are excellent steels. 4140 is more commonly used by riflesmiths.

Dan

I understand from the Maryland AR-15 site that Bushmaster uses MIL-SPEC 4150, and famed US barrel maker Boot Obermyer is recommending 4155 for precision (target) barrels.