Supersonic load on 4.5" barrel able to defeat IIIA body armor?

[Ghost12three]

Hey guys, this is my first post here!

I'm considering ordering a custom barrel from White Oak Precision with the follows specifications: 4.5” Medium Profile (.750”), Pistol Length Gas System, 1:12 twist, 300 BLK, 0.067" gas port diameter, 416R stainless steel (which would cost around 190 bucks).

Here's my doubt: I intent to shoot supersonic only, through a SIG SRD762 sound suppressor. But I'm not 100% sure that it will be able to defeat level IIIA armor. So, do any of you know if it would maintain soft armor piercing capabilities with such a tiny 4.5 inch barrel? Thanks in advance!!

[rebel]

Not flaming you at all, you mind explaining why you need to defeat body armor?

[Omega]

Yup, and how would you know you're going against Level IIIA?

[Ghost12three]

Not flaming you at all, you mind explaining why you need to defeat body armor?

Well, it's because it would be a lot cheaper and convenient (specially because of ammo availability) to have my AR-15 chambered in 5.56 with the same 4.5" barrel length. The reason why I don't like this idea is because this caliber has suboptimal fragmentation when out of a barrel shorter than 9 or 10 inches. I'd like to have an SBR with the same lethality of a normal sized 5.56 counterpart, but way more compact. The lethality I'm talking about is being able to use this rifle against cheap and commonly available pistol rated body armor, that can be used by any home invader or active shooter. I've seen videos showing subsonic 300 BLK expansive loads being stoped by level IIIA panels, but I can't find any data regarding supersonic rounds out of very short barrels against any type of soft armor.

[Ghost12three]

Yup, and how would you know you're going against Level IIIA?

I don't actually know that. I'm just not going to have a .30-06 loaded with black tips just in case I need to shoot someone wearing level IV plates. I already know that most hard plates will stop most 300 BLK rounds. I just don't want to think that my stubby barreled AR will easily pierce soft armor if in reality it doesn't. I don't want the same firepower of a 9mm AR with a 31-rd mag in it. I want to make sure that only rifle rated hard plates can stop my rounds, not any common soft armor vest out there. Guess I'm being too serious about "overmatch" and SHTF haha

[golfindia]

http://www.garysguns.com/exotic.htm

50cal AP incendiary, $6.00 each. In case the the robber has IIIA and is riding in an MRAP.

[Ghost12three]

http://www.garysguns.com/exotic.htm

50cal AP incendiary, $6.00 each. In case the the robber has IIIA and is riding in an MRAP.

I just need the transferable M2 now.

[bangbangping]

If it were me, I'd give up 3.5" of compactness for a 60% increase in energy. But then we may have different priorities.

[dellet]

Let’s start with the basics.

A pistol port will not work at 4.5”.

A 220 SMK will penetrate 2” bullet proof glass at subsonic speeds but won’t defeat IIIA level armor. If it’s not plate, it will cause about 3-4” of stretch into what ever backs it up.

It will have the energy to penetrate as a super, so it will be completely dependent on bullet design.

So the simple answer is the bullet can work, but the barrel as specified won’t.

Then there is the whole issue of a can that will hold up to the muzzle pressure issue.

[Ghost12three]

If it were me, I'd give up 3.5" of compactness for a 60% increase in energy. But then we may have different priorities.

Despite the energy losses, am I going to defeat IIIA or lower levels with supers through this 4.5" barrel?