300 Blackout +P+ Supersonic out to 700 Yards out of 12.5 barrel.

Walter experiments with the latest case technology and projectiles to take 300 blackout Super Sonics to the limits.

Walter has been busy in the workshop testing and revising a hand load that maximizes the performance of 300 blackout supers for hunting and longer-range terminal effects on target.  Using modern casings from shellshock and solid copper projectiles, performance is possible with 300 Blackout that hasn't been explored. Walter has been busy tinkering in his shop and exploring that line. 

Before we dive into this specific flavor of home-rolled goodness, we should establish what Walter wants to accomplish with 300 blackout supers.  Walter wants to exceed the terminal and external performance of 556 for a given barrel length and have a hunting platform capable of taking a deer out to 350-400 yards out of the smallest and lightest platform possible.  Walter will go into his preferred platforms for this in another write up but for the sake of today's discussion, we are focusing on the engine in the car. 

By exceeding the pressures and powder capacity of traditional brass cases, we get some very interesting results with 300 blackout supers.  As of 2024, Shell Shock is the only gig in town for 300 Blackout bi-metal casings, hopefully companies will release hybrid casing like the Sig 277 Furry in other cartridges.  This will open more room for tinkering and exploration, but 1500 pieces of Shell Shock 300 blackout cases is where Walter started his exploration.  Walter ordered .30 cal solid copper projectiles in the 120 to 138 grain range from companies ranging from Barnes, Maker, Cutting Edge, and Discreet Ballistics to start exploring the optimal balance of velocity, Standard Deviation, accuracy and expansion.   On the recommendation of David from Discreet Ballistics, Walter focused his efforts on LIL Gun powder and started cranking loads.

After 500 rounds of trial and error, Walter has settled on the combination shown here. A Barnes 120 TSX projectile, 20.5 grains of LIl Gun, cci 450 primers, Shell Shock NAS3 cases and an overall length of just over 2.3 inches.  Bowlers, try this at your own risk,  if you blow up your gun and blame it on Walter you are a loser and a fool.   

Walter, in this application prioritizes a balance of velocity, as this is needed for expansion and range, Low Variation in Velocity and acceptable accuracy.  Most handloading is done with an emphasis on accuracy over the other two variables but Walter believes this doesn’t always make sense, especially when it comes to hunting where a velocity threshold is needed for expansion of projectile and energy on target is important. 

Walters spicy handloads send the Barnes 120 TTSX out his 12.85-inch Proof barrel going 2380 FPS with a standard in the mid-teens, and on the most recent outing, printed a hastily shot 10 round group in the 1.75 moa range.  With an observed G1 bc of .36, the Barnes 120 drops below the advertised velocity needed for expansion (1400 FPS) at 500 yards and below the speed of sound at 675 Yards.  Walter won’t take a shot at a deer at more than 350 yards with this set up, assuming the vital size of 10 inches and his cone of fire being around 6 inches at that range.  At 350 yards, the Barnes 120 still has 738-foot pounds of energy.  I don’t know about you fellas, but that makes Walter's Johnson hard!

Let's make a little comparison.  Walters 12.5 556 does around 2562fps with a 77 grain OTM with a near identical g1 BC of .36.  The 77 grain SMK drops below the 1900 FPS range needed for fragmentation at 300 yards, at 350 yards has 561 foot pounds of energy, and drops below the speed of sound at 750 yards.  Walter's 120 grain 300 black loads embarrass the 77 grain otm across the board falling just short of a maximum transonic range, by 75 yards. 

Well, Walter, What about something that weighs around 120 grains and that’s doing a similar velocity, all be it out a longer barrel, the venerable 6.5 Grendel?  Well let’s take a look there. The Barnes Vor-TX 115 Grain 6.5 Grendel has an advertised velocity of 2510 out of a 24-inch muzzle (twice as long as Walter's mini fix mind you) with a g1 bc of .387.   This gives the 115 another 100 yards of supersonic travel, and another 100 Foot Pounds of energy at 350 yards, and another 100 yards of expansion range than Walters 300 Blackout handloads.  Does that performance warrant the barrel being twice as long?  Hell no it doesn’t.  What would lopping off 12 inches of barrel get you vecloty wise? Maybe 2100 FPS?  This brings  the advantage of 300 blackout supers where the increased bore diameter gives a bowler more efficient energy transfer for a given powder charge out of a shorter barrel. 

So what you're saying, Walter, is that with modern bimetal case design, purpose built 300 blackout high bc projectiles and an ass-load of powder, you can get 6.5 Grendel supersonic performance out of a 12.5 inch 300 blackout and be just a mag change away from having a silent, but deadly subsonic hunting with a load like the Discreet Ballistic 188 Selous round?   The future is now, and Walter’s dear friend, Garand Thumb, might have been blowing smoke up your ass.  300 blackout most certainly has a place in the bowlers closet especially when it comes to "longer" barrels like the 12.5 inch where you get ballistics that match or exceed 6.5 Grendel all while retaining the beloved subsonic option. 

If you're a reloader, it's a great time to be tinkering.   For bowlers that haven't taken the leap into the realms of self-reliance, time wasting, and money wasting of reloading, we must demand that small ammo makers take the leap, get with the times and start loading up ammo that captures the potential of 300 blackout supers. Walter has been talking to Blackarc Munitions about loading up a similar to concoction to his spicy home brew shown here. David from Discrete Ballistic has been a constant source of info. They have great projectiles and could whip something up very promising with their 136 VLR4 Projectile.

Research like this takes a long time and lots of energy, Considering joining Walter’s substack and support the R&D.