Corbon .223 Rem 77gr. MPR for Home Defense?

[ST911]

The OP wanted to know about Corbon. If anyone has real life no shit info regarding that ammo, please sing out.

As you and others process feedback, remember that Corbon changed hands early in 2018 and legacy info may not be applicable to new production.

[SeriousStudent]

That's right, I forgot about that. Is Peter Pi no longer at the helm?

[LimeSpoon]

I don't have much experience with the Corbon load in particular, but I have done some research and gel testing on the 77 gr TMK in general.

In a home defense environment, YMMV but I think the TMK's comparative lack of barrier blindness compared to bonded soft points is probably not a very large problem. Granted I haven't seen barrier tests of that particular bullet in 10% ordnance gel, but Le.vista Outdoor's site does contain data on the 168 gr Sierra Tactical Tip Matchking, and the penetration doesn't change in wallboard and plywood. It's also been stated by Dr. Roberts that polymer tipped bullets in general have better - if still inadequate - glass performance compared to traditional SMK BTHP.

I'm not sure how the construction of the 168 gr "Tactical Tip" Matchking differs from that of the TMK, but I would assume it's comparable, as the performance of the bullet in bare gel is pretty much exactly what I'd expect out of a 168 gr TMK. This comes with the caveat, though, that .308 tends to have better barrier performance than 5.56, given the same projectile design.

To call back to our late E4's question concerning 55 gr FMJ vs 77 gr TMK at close range...assuming proper fragmentation with both (an effect not guaranteed with the former), yes I do think the TMK would be more effective on average in practical terms as well. Hunters who have used this bullet report a maximum wound cavity of approximately 4 inches across. Even outside of the main "hole", bullet shards can still spread out and hit structures peripheral to the wound track; in my personal gel testing of the Black Hills loading with a 16" barrel, I observed fragmentation covering an area about 5 inches across.

Not to be too macabre about the whole thing, but I would have to echo an unrelated tester's sentiment that a single 77 gr TMK to the center of the chest is likely unsurvivable short of organ transplantation. The sheer size of the damage track would also mean that your center of aim could be slightly off the thoracic cavity, and you could still hit, although obviously this is not something to be relied upon.

Now, in reference to the MPR, it's possible that the addition of the cannelure on the Black Hills exclusive component might slightly increase penetration and decrease expansion. The reasoning behind that bit of speculation is that I've observed that the copper jacket petals tend to break off around the cannelure point, and it seems with an non-cannelured bullet that the projectile may be more prone to continuously expanding down without ever hitting a "speed bump." In addition, pressing the jacket into the core would, in theory, form a little bit of a lock on the whole structure. However, without actually doing extensive testing, that's all merely conjecture.