300 Blackout Effectiveness - Care to comment Doc

[OldGrayGuy]

I haven't been following firearms development that closely in recent years and am trying to get caught up on the 300 Blackout. I am about to purchase an AR-15 for home defense. After doing a bit of reading on the web I am wondering if I should consider this caliber instead of 5.56mm.
I realize it is a relatively new caliber and may not have been involved in enough real world shootings to determine its superiority or lack of as compared to 5.56. Excluding ammunition costs - strictly terminal effectiveness which would you choose and why. Appreciate your chiming in if you get a chance Doc and thanks for your participation on this forum.

[MegademiC]

A search will provide the info you seek.

for example:
https://www.m4carbine.net/showthread.php?t=96366

6.8 is better terminally. However, 300 uses all standard parts except for barrel.
300 is also the way to go if you want a quiet silenced gun.

both rounds offer better performance than 5.56/.223.

That said, 5.56/223 is fine for hd. It is also readily available and cheap to train with.

[DocGKR]

For a first AR15, get a quality 16" 5.56 mm like a Colt 6720, BCM, LaRue, Centurian, etc... This will prove more than adequate for any HD needs, as well as provide a good rifle to acquire adequate training.

The .300 BLK is very versatile as it can do the same job as well or better than suppressed MP5's, 5.56 mm SBR's, and AK47's. External and terminal ballistics are equal to or better than the well proven 7.62x39mm.

With barrier blind projectiles, .300 BLK is an ideal caliber for both Patrol and Tactical LE use, as it offers outstanding terminal performance and intermediate barrier capability in the critical 0-100m range and remains capable out to 300m or so. A perfect barrier blind LE load should ideally offer penetration in the 12-18" range--perhaps something like a Remington CLUB, Speer Gold Dot, or Federal TBBC design will optimize the .300 BLK for LE purposes.

The Barnes 110 gr Tac-TX is very close, however, penetration is a bit deeper than ideal for CONUS LE use--much like the 5.56 mm 70 gr TSX. I see the Tac-TX as a great load for military GP use.

In addition, using the TTSX or other barrier blind loads, the .300 BLK becomes an outstanding choice for hunting up to med game and can be used in any hunting situation that is appropriate for lighter .30-30 loads.

Note that for a pure hunting rig, I'd likely go with a 6.8 mm, as it offers greater range, capability to go after a bit larger game, and a wider range of hunting loads, but .300 BLK has a lot going for it.

As with any of the alternate AR15 calibers, have an identically configured 5.56 mm upper and do the majority of rote training using that to reduce costs (especially if you get free 5.56 mm ammo at work) and save the larger caliber for duty/hunting use.

[Vash1023]

you could always get an LMT MRP cqb and then purchase the 300blk barrel down the road.

you can change the MRP barrels in about 2 mins.

not exactly the cheapest option but you get the best of both worlds.

[Eurodriver]

you could always get an LMT MRP cqb and then purchase the 300blk barrel down the road.

you can change the MRP barrels in about 2 mins.

not exactly the cheapest option but you get the best of both worlds.

How long does it take to re-zero once the barrel change is made?

[Cincinnatus]

How long does it take to re-zero once the barrel change is made?

Re-zeroing is usually unnecessary with the MRP. POI only changes very slightly--however, I do not know if this is till the case when changing to a different CALIBER of barrel.

[Vash1023]

How long does it take to re-zero once the barrel change is made?

LMT claims that no rezero is required.

obviously the caliber difference will change the flight path of the round so but you could just do up your own personal chart and memorize the drop at distance and just adjust for it during aim.

[Elessar]

Just to point out the obvious, an alternative to the MRP idea is just to simply have two complete uppers. Not only is this cheaper, easier, and faster to change, you also can keep the optics on each one.

[Army Chief]

Just to point out the obvious, an alternative to the MRP idea is just to simply have two complete uppers. Not only is this cheaper, easier, and faster to change, you also can keep the optics on each one.

Sound counsel, even if it inevitably leads to the nagging feeling that you really need another complete lower ...

AC

[Gatorbait]

Just to point out the obvious, an alternative to the MRP idea is just to simply have two complete uppers. Not only is this cheaper, easier, and faster to change, you also can keep the optics on each one.

I have found this set up to work very well.