Mossberg 590 Shockwave 20-gauge buckshot selection and patterning

Mossberg 590 Shockwave 20-gauge buckshot selection and patterning

The arrival of the non-NFA Mossberg Shockwave and Remington TAC-14 14″ barrel “firearms” has been well received by shooters. While some would question the utility of these short barreled firearms, most agree they are fun to shoot. The downside of not having a shoulder stock is that these firearms can be punishing to shoot during long sessions at the range. At the time of their introduction, it only seemed natural to introduce 20-gauge guns to mitigate this, which Mossberg and Remington (TAC-20) both did in short order.

My friend recently purchased a Mossberg 590 Shockwave in 20-gauge. We had a lot of data on the 12-gauge guns and nothing on the 20, so we decided to take a look at a few different loads. While 20-gauge isn’t as popular as 12, ammunition tends to be abundant- that is if you are looking for shot shells. As soon as you start looking for buckshot, the choices, especially when you shop locally, become fairly narrow. We were able to obtain four different types locally.

We headed to the range with the 20-gauge Shockwave to see which one the gun liked best. These loads included:

Before we shoot, let’s take some time to review buckshot sizing. For reference purposes, perhaps the most popular choice in 12-gauge is 00 buckshot which has a pellet diameter of .33″ and a weight of 53.8 grains. Since we have a smaller payload in the 20-gauge, we tend to use smaller shot. In this case the #1 buck is .30″ in diameter with a mass of 40.5 grains, #3 buck has a diameter of .25″ with a mass of 23.4 grains, and #4 has a diameter of .24″ with a mass of 20.7 grains.

To begin, we set up a target at 7 yards (21 feet) and fired one round of each load. The results are shown below.

I realize that each shot is only a sample size of one, however, it does give you a representative indication of how each load will perform. Patterns were measured at the point of maximum dispersion and rounded to the nearest .25″. Pattern sizes ranged from 3″ (Rio #1) to 6.75″ (Remington #3). The Federal #3 load (5.5″) and #4 loads (6″) had similar patterns at this distance.

Much to our surprise, the Rio shot far tighter than the rest of the loads. We hung a new target and patterned the gun at 10, 20, 30, 40, and 50 feet (beyond 50 feet for these guns without some sort of sighting system is a bit of stretch). Results are shown below.