FMJ vs. Bi metal AR .223

It does wear barrels and extractors faster, but not much. Usually the price advantage will buy you barrels faster than you wear them out.

Shoot all you want.

I'm confused as to what the OP is asking.

Brass cased vs steel cased?

Or standard FMJ vs. penetrator rounds (green tip)?

Bi-metal refers to the bullet, not the casing, unless someone is using the term incorrectly or lacking specificity.

So steel case is cheaper than brass case?
Is there more mis-fires or hang up with the steel?

I know of 4 different metals used in bullet production - copper, lead, nickel, and steel. There are other alloys used in some like depleted uranium in the 30mm canon on the A10 Warthog and the core of the penetrator round that is made of a combination of metals.

Obviously copper and lead are the two most common types commonly seen. There are also all-lead (cast) and all copper (like Barnes) bullets on the market too.

Nickel-plating is used as a jacket on the Winchester Silvertip pistol rounds. But the only advantage that they serve is to be much less corrosive than copper jacketing. In seeing tests, they have a greater chance of separating from the lead core.



The military 5.56 "green-tip" is the penetrator round. It has a copper jacket coating a steel penetrator on top and an alloy in the rest of the bullet. This is why certain ranges like to see the type of 5.56 rounds you shoot at the range so you don't damage their backdrop.





The oddball of the group interestingly is Coonan 357 Vampire rounds. They have done a promotional thing recently where they actually coated some rounds with a true silver jacket. These are very expensive and obviously not true range or defense rounds, but they sure are cool.





As to brass and steel cases, neither of them will hurt your rifle but the steel-cased ammo may be a bit harder on your extractor and ejector. The steel also has a greater chance of jamming into your chamber, but this is a pretty rare occurrence.

Have a DPMS and I'm not sure if I'm keeping or sell/trading it.
My buddy has the exact gun with the Trijicon scope and as I fish 95% of the time it may not be feasible for me to keep it..
Thanks everyone for all the info...