Why The Two Different Loads For 300BLK?

A fair amount of you have asked me about the reasoning for Discreet Ballistics having two different loads for 300 Blackout. We make a Pistol/SBR load which is optimized for barrels between 7-11” and a Carbine load which is optimized for 16” barrels. The reasons we offer these two different loads is due to the inherent velocity loss encountered with when shooting a load designed for a 16” barrel out of a shorter barrel. This velocity loss can be as much as 200fps. While this lower velocity doesn’t necessarily make the bullet any less accurate it does have a couple of downsides:

  1. The lower the velocity the longer the bullet stays in flight. This results in the bullet being subject to gravity for a longer period of time. If a rifle is zeroed for 50 yards shoots a round with a muzzle velocity of 1050fps the 190gr bullet will exhibit a 6.7” drop at 100 yards. Conversely, a round fired with the same 50 yard zero with a muzzle velocity of 900fps the 190gr bullet will exhibit a 9.5” drop.
  2. Energy delivery will also suffer with a lower velocity. Using the same numbers the bullet with a muzzle velocity of 1050 fps will have 422ft/lbs of energy at 100 yards while the bullet with a muzzle velocity of 900fps will only have a 322ft/lbs of energy at 100 yard. These numbers are particularly important for putting down game.

Ballistics Chart for bullet at 1050fps Muzzle Velocity (courtesy JBM Ballistics)

Ballistics Chart for bullet at 900fps Muzzle Velocity (courtesy JBM Ballistics)

So why don’t other subsonic 300 Blackout manufacturers make two loads to accommodate both long and short barrels? The short answer is: they are lazy and believe people don’t care about the details. The difference with Discreet Ballistics is that we know that there are always folks out there that want to get the optimal performance from their rifles no matter which caliber they’re shooting.

Indonesia: PT Pindad SS2-V7 Subsonic

SS2 V7

SS2 V7 Subsonic

On June 9th, 2016 the state-owned Indonesian defense company PT Pindad launched four new small arms systems. Included was a new rifle named the SS2-V7 Subsonic. This new rifle is based on the standard issue SS2 which was introduced to the Indonesian military in 2006. The SS2 is an entirely Indonesian designed weapon and was developed to replace the SS1 which was a licensed copy of the Belgian FN-FNC. The SS2 uses a gas piston design similar to the Kalashnikov.

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Pindad SS2

The SS2-V7 Subsonic appears to have a much shorter barrel with a larger suppressor attached at the muzzle. No details yet have been released about the ammunition but the rifle appears to be chambered in 5.56. Shooting a subsonic 5.56 round in a standard AR-15 platform requires the need to cycle the action manually due to the lighter load not being able to throw the BCG far enough to eject the spent case and pick up another round. Some modifications with springs and gas systems have been attempted in an effort to get the Ar-15 to cycle reliably using subsonic ammunitions and these modifications have been met with varying degrees of success. The modifications will invariably require a heavier than normal projectile to increase gas pressure. No word has been given yet as to the type of ammunition the SS2-v7 would use but assuming a 75 Grain bullet you can expect the following trajectory numbers (Courtesey of JBM Ballistic Calculator):

 

Range Drop Drop Windage Windage Velocity Mach Energy Time Lead Lead
(yd) (in) (MOA) (in) (MOA) (ft/s) (none) (ft•lbs) (s) (in) (MOA)
0 -1.5 *** 0.0 *** 1052.2 0.942 184.3 0.000 0.0 ***
100 -0.0 -0.0 0.0 0.0 993.7 0.890 164.4 0.294 51.7 49.4
200 -33.7 -16.1 0.0 0.0 946.5 0.848 149.2 0.603 106.2 50.7
300 -106.1 -33.8 0.0 0.0 906.4 0.812 136.8 0.927 163.2 52.0

 

The table shows a trajectory numbers that are similar to a subsonic 300AAC bullet, however energy delivery tells a different story. Energy at the muzzle is at best equivalent to a standard FMJ 380ACP round. This is less than half the energy delivery of a standard 300AAC cartridge. For close in operations a suppressed SMG like the MP-5 SD may be a be better choice. However, this setup might be a good choice if an entry team member is carrying magazines loaded subsonic and supersonic which could easily be switched out after taking out sentries and/or lights in a stealthy manner.

 

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SS2 V7 Subsonic

 

 

 

From Russia with Love: Lobaev Arms DVL-10 Saboteur

Lobaev Arms DVL-10 Saboteur

dvl-lobaev-1-660x495

The Lobaev Arms DVL-10 Saboteur is an integrally suppressed sniper rifle system that is designed for relatively close ranges. Along with standard 308 Win, the DLV-10 uses a new proprietary cartridge called the 40 Lobaev which sends a 419 grain bullet at subsonic velocities. At 1017 fps the muzzle energy works out to 962 ft/lbs which is significantly more energy that even 338 Lapua subsonic, which at 1000 fps pushes a 300gr projectile with 666 ft/lbs of muzzle energy. This is very impressive even with significant bullet drop occurring past 100 meters. See below for chart courtesy of JBM Ballistics:

Calculated Table
Range Drop Drop Windage Windage Velocity Mach Energy Time Lead Lead
(yd) (in) (MOA) (in) (MOA) (ft/s) (none) (ft•lbs) (s) (in) (MOA)
0 -1.5 *** 0.0 *** 1018.5 0.912 965.0 0.000 0.0 ***
100 -0.0 -0.0 0.0 0.0 976.8 0.875 887.6 0.301 53.0 50.6
200 -34.9 -16.7 0.0 0.0 941.1 0.843 823.9 0.614 108.1 51.6
300 -109.1 -34.7 0.0 0.0 909.6 0.815 769.7 0.938 165.1 52.6
400 -225.2 -53.8 0.0 0.0 881.3 0.789 722.5 1.274 224.2 53.5
500 -386.2 -73.8 0.0 0.0 855.3 0.766 680.5 1.620 285.1 54.4
600 -594.8 -94.7 0.0 0.0 831.3 0.745 642.9 1.976 347.8 55.4

 

According to their Facebook page Lobaev Arms is a Russian manufacturer of high end precision rifles and was founded in 2005 and is located in Kaluga which is 150KM southwest of Moscow. They purport to be suppliers of sniper rifles to Russian security services which may be unprecedented for a privately operated company operated in Russia. The Russians have a history with using subsonic ammunition in accurized platforms. The VSS Vinorez, which is in service with the Russian armed forces utilizes the 9×39 cartridge.  I’m not holding my breath for these to be imported into the US for civilian sales, however the 40 Lobaev would be an excellent choice for those needing a subsonic platform and require the additional energy delivery at close ranges.

 

PERFORMANCE CHARACTERISTICS:

  • Precision – 0.5 MOA\15 mm distance between the centers (5-shot at 100 m)
  • Maximum range – 600 m
  • Muzzle velocity – 315 m/s
  • Operating temperature range – -45+65 C
  • Caliber – .40 Lobaev Whisper \ .308 Win (civil)
  • Length – 1004 (730 with folded stock) mm
  • Height – 226 mm
  • Width – 62 mm
  • Weight – 4100 g
  • Barrel length – 400\600 mm (civil)
  • Trigger pull – 500-1500g
  • Bolt handle – right
  • Bolt action – right
  • Magazine – 10 rounds

Standard package:

  • Barrel contour – special contour
  • Barrel length – 500mm
  • Caliber – .40 Lobaev Whisper (308Win – civil version)
  • Bi-pod – none
  • Suppressor – LIS
  • Scope mount – STD Picatiny rail