Product Review

40mm to 20ga

Rifled Adapter and Explosive Ammo



Written by GROG


This review is going to be on a new adapter that fires all standard 20 gauge ammo and specially made explosive rounds! Nick Ferris provided me with many samples of his exploding 20 gauge slugs and an adapter he specially built to fire them. Since the rounds must impact point first, the adapter is rifled. It contains a rear aluminum piece that simulates a 40mm shell, in which the 20 ga barrel is mounted. It comes with an extractor for the 20 ga casing. The barrel is 11" long, so it stops inside the 203 tube. At the end of the barrel is another aluminum piece with a rubber ring seal, to keep from damaging the 203 rifling. The adapter fits snugly into the 203 tube, and must (at the present time) be mounted with the 20 ga extractor facing down, so as to defeat the 203 extractor. The adapter adds a little weight to the M-203 (noticeable when mounted on a carbine). This adapter is made for use in either the M-79 or M-203 weapons. The ammo is specially made 20 ga slugs, extra long. They contain an impact detonator and small charge of flash powder. They pack quite a bang when they strike hard objects! They need to impact point first in order to detonate, and need a very hard impact to set them off. (I don't believe dropping them would do it, but be careful anyway... I wouldn't drop HEDP rounds either, even though they have spin armed fuses...) This adapter would also be a cheap alternative for LE agencies in training with the 203 or 79.


Here's a view from the rear. Notice the 20ga extractor and steel rifled barrel.


Here's a look at the barrel (or bidness) end!

The rounds are very fun to shoot, and in-expensive also, as compared to other 40mm rounds. I would recommend these rounds for a very fun day at the range. They are great little noise makers. When used, make sure you don't fire them within 30 yards of yourself or others, as when they explode, there is a possibility of fragments within the burst radius of the rounds. The tested adapter came in unfinished form, however the finished model will be anodized or have other finishes applied. To order or for information on the adapters e-mail Nick at: