OP,
I had the same question a while back. After putting together my first one, I couldn't be more happy with my 300blk pistol. Here are some random thoughts and why I went with 300blk AND the pistol platform...
- The 300blk rounds lend themselves well to a short barrel. You'll find that most 300blk ammo will burn the entire gunpowder charge within a 9" barrel. Not true with the 5.56 NATO round. Launching 5.56 rounds from a 9" barrel will result in substantial muzzle flash and pronounced bang.
- The recoil on my 300blk with supersonic rounds feels no different to me than a traditional 5.56 mid-length gas system weapon. Very little muzzle rise and relatively low recoil.
- My particular BCM upper is surprisingly accurate. Almost jaw-dropping accurate. Like we're talking 1MOA or better (within 100 yards anyway). With my Aimpoint on top of this pistol, I can bring the weapon from low/high ready to shooting position, acquire target, and put a round (or 10) exactly where I want it PDQ.
- You can choose to shoot the 300blk in traditional or subsonic velocities. Subsonic is great for suppression and traditional velocity puts the hurt on most prey. You don't have these options with 5.56
- Choosing a pistol platform over an SBR build can give you more flexibility. A pistol, for example can be carried in a vehicle (loaded) in many states (check your local laws). Conversely, these same states may prohibit loaded rifles in vehicles.
- You may also find that hunting with a pistol is allowed in some jurisdictions, whereas hunting with an SBR is not allowed in those same areas.
- 300blk ammo is more expensive than 5.56, but I'm okay with that. Especially considering the aforementioned advantages. This weapon is not for plinking on a sunny weekend afternoon for hours on end.
- My ammo selection is currently Barnes VOR-TX 300 Blackout 110gr TAC. Wicked round. For target practice/training, I typically go with something more affordable (e.g. S&B, Fiocchi, etc.)
WOW, you really tipped the scales toward 300 blk!!!