Saga of the MP40 and the baffle box
Stopping steel and lead in its tracks
By Dennis Adler
My recent exploration of the MP40 weathered model’s accuracy proved to be quite exceptional. After Thursdays article, I went back and shot several more magazines to test quick reloads (I have one spare magazine) and firing with the gun shouldered and my support arm through the sling (as pictured) my groups from 25 feet kept getting tighter. This is one very accurate CO2 air rifle on full auto, especially shooting in short bursts. I average six to 10 shots by feathering the trigger, i.e. just enough pull to fire the gun but not an extended trigger press, on and off in under a second. You can hear it and feel it in the bolt’s recoil so less than a second and you’ve got it. Some of you have already tried this using the shoulder strap to really stabilize the MP40 from the shoulder and are getting the same kind of accuracy, so I haven’t done anything exceptional. What I did do, however, is blow the entire center out of my baffle box! I usually get about 10 gun tests done before I have to make a new baffle box. I shot this one to piece in two days with the MP40.
Baffle box theory
I’ve thrown the term baffle box around a few times before but never explained what it is. There is more than one way to make a baffle box, and my system is simply what I developed by recycling boxes and cardboard around the house. This basically costs nothing but your time. You can also buy ready made ones, but you will wear them out as well and since cardboard is cheap and so are cardboard boxes you can make one rather inexpensively. Some people just stuff a box with old newspapers and shoot into it. That works with BB guns and some lower velocity pellet pistols, but I like to build a baffle box that stops them dead in their tracks. I shoot both outside and indoors (basement) at anywhere from 21 feet to 10 meters, a little further sometimes when I’m outdoors, but I like to trap all my rounds, even outside. My baffle box design varies in overall dimensions but usually measures 11 x 14 inches and 10 inches in depth. That sounds small, and it is, but I have been shooting for 40 years and I rarely hit outside of a 4-inch radius even with cartridge firing handguns from 25 yards. A good size for most shooters should be a 20x20x20 square box; that gives you a good margin with airguns at 21 feet to 10 meters. The depth isn’t as important so long at it is at least 10 inches, if you build the baffles correctly. My baffle box will stop a 4.5mm pellet from the Sig Sauer MCX at 10 meters.
The inside of the baffle box, constructed properly, will outlast the outside for a long time. Usually when I’ve punched a lot of holes through the front of the box, I’ll patch in a new front board to keep from making an entirely new box. The MP40 kind of used up a lot of gun tests all at once! So here is how to make my kind of baffle box.
Shipping boxes are your best friend
Cardboard is like metal, it comes in all gauges (thicknesses) and qualities. Cardboard from China is junk (no pun intended) and won’t stop your finger let alone a BB or pellet. You need good shipping box cardboard (the Uline catalog has great choices in heavy duty cardboard boxes 20x20x12) but you probably get shipments from one vendor or another that use good quality cardboard, so pick one that is a size you are comfortable with and make your own baffle box.
It is how you build the baffles inside the box that make it effective at stopping BBs and pellets at up to 460 fps. As the photos illustrate the heavy cardboard that is bent into a V shape is in layers and the BB has to pass through each, slowing it down as it goes. I have yet to have a BB or pellet make it to the fourth baffle; most stop at the second, higher velocity rounds still won’t get past the third baffle.
In the disassembled baffle box photos you can see there is a smaller front box filled with paper (or heavy plastic) which takes the initial hit as the BB passes though the target and the cardboard box. By the time the BB hits the first baffle it is already slowing down. BBs seldom get past the second baffle.
This is a very inexpensive and simple way to shoot indoors and out that prevents BBs or pellets from getting past the target. Not at all baffling, just shoot straight and hit the bullseye.
Next week, we will begin a series on target shooting and dedicated target pistols starting with an old friend.