The PP-19 Bizon and the FN P90 came from a theory and generation of submachine guns that emphasized maximum capacity and minimum space. The ergonomics of a smooth reload didn’t make the list of considerations. The reloads were able to be done and that was pretty much that. That compares in ill favor to what we have nowadays where the reload ergonomics are absolutely a major part of our control scheme designs.
So Garand Thumbs gun video on the PP-19 complete, why did we delve down this high capacity slow reload line of design?
Simple, we were gambling. Balancing is really the proper term, we were balancing the likelihood we shot through an entire magazine while still in contact with an active threat and therefore requiring a reload with the troops and missions these little guns excelled at. The P90 has 66% more ammunition on deck than the MP5 or AR-15. The PP-19 Bizon, in its native 9×18, has 113% more (64 rounds) and the type of fight these guns were meant for was the one magazine engagement and the well supplemented gunfight.
One Magazine Engagement
What is that?
You already know actually, at least one version. The home defense shoot is nearly universally a one magazine engagement. Even against multiple attackers a single standard capacity magazine is going to resolve the fight with the assailants stopped or fleeing. Prolonged gunfights are a true superminority outside the purview of organizations in conflict.
The P90 and Bizon are excellent examples of relying on an over standard capacity to carry the fact that the reload, if necessary, can be done administratively/tactically between fighting sequences as opposed to in the middle of a gunfight. Even in professional PSD type work (the Secret Service likes the 50 round P90 comparatively to the 15-20-30-32 round 9mm guns like the UZI and MP5.
Well Supplemented Gunfight
Here we get back to the fact that the PDW is meant more for vehicle crews in one of its principally designed rolls, therefore the folks using these high capacity yet slower to reload weapons have supplemental protection in many cases.
They’re in something with a much bigger gun.
Armed and armored vehicle, helicopter, APC, whatever it happens to be they can roll with the support of a much bigger gun and the little PDW fills in the gaps.
High Capacity Today
With Magpul and a few others releasing high reliability high capacity magazines for 5.56 and 7.62 carbines, the niche of guns like the Bizon and P90 has narrowed even further. Instead of relying on a PDW style gun with an overcharged magazine to make certain you don’t run out of on rounds when that would be highly inconvenient, the reliable drum magazines give that same capability with full power rifle rounds. The trade off, as there is always a trade off, is weight.
The D60 and D50 make guns heavy. No weigh around it [/pun]. But if its a staged gun instead of a carried gun, that is very manageable. A carbine being carried by a vehicle, or stored in a quick access static space like a locker or bedside, helps manage that transport of that additional weight. It is only every picked up when in actual use to shoot, where the extra capacity is most likely going to benefit the user.
The Compact PDW types then get slotted into the roll of high capacity yet “easy” to carry still. The P90 and Bizon would still both sit reasonably comfortably beneath an arm in a shoulder rig where a PDW sized AR with a D60 or Surefire would not. They also store into very small spaces reasonably well with a magazine in place, something that a traditional carbine again does not do well.
So these guns still have a roll and are still very cool, but for many rolls there are simply better fits.