Ok, so let's discuss steel cased SEMI AUTO ammunition. Before we can talk about this subject, I must discuss a little physics. Newton's Third Law states.."When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body." So how does this relate to firearms? Not only does it relate to firearms but it related to everything that we do in life, however I will stick to the subject. What this means is, when a cartridge is ignited in a barrel, the initial blast causes the cartridge to move longitudinally rearward, however it can not move but a minute bit before it rests against the bolt face. Newtons Law takes effect and the cartridge will try to move forward. Here it engages the forward lip of the casing against the inside of the chamber and contacts the throat rim just prior to the lead, better known as the area before the lands and grooves start. Phewww... explained. Ok so brass being softer than steel has very little impact on the "throat erosion" of the barrel until subsequent amounts are fired through the firearm.
Stay with me. Another property is, you can not increase temperature without an increase in pressure and vice versa. Essentially what I am trying to explain is the casing is like a miniature jack hammer for a split second that slams first rearward then forward. Imagine if you will, what will happen if you feed your barrel steel cased ammunition constantly. My mental picture is not good. This becomes a gunsmiths nightmare, not to mention that almost every manufacturers owners manual or web page it states if you used steel cased ammo it will void your warranty. Another terrible scenario is what about rust? What about leaving that steel cased ammo in the chamber and moisture from humidity or anything else reaching it. It will lock your weapon CLOSED!
I think you get the picture. Hopefully I have made you think and changed some minds when it comes to your ammunition choice. Remember if you take care of your firearm, it will take care of you!
Some Points of Interest!
NFA Lawyer- WWW.NFALAWYERS.COM
Veterans Fly Fishing Outreach Program- www.projecthealingwaters.org