..a boom-box. This is something akin to Gary's "muzzler", and is my 4th or 5th attempt over the last year or two to build a device to quieten my big bores without using a silencer (legal here in New Zealand) which I have found compromises accuracy beyond 50 yards.
So my early attempts were square, or nearly square, boxes, filled with various foam rubber products and a baffle or two. Neither of the last two were particularly successful. Then I decided that a rough crate that once contained an airgun shipped to me might be a framework for a long, thin boom-box that would be more efficient than my previous attempts....here are the earlier two, with the rough bit of crate intended to be version #5 on top...

So I made up a series of plywood baffles, and faced one side with neoprene from and old wetsuit, on the side that would face the sound..

You'll see to the left of the picture I am using strips of acoustic foam to space the baffles apart. My intention was that they would not be firmly fixed, rather they could move a little to help absorb the blast of sound. I arranged the baffles so that there were 6 at the exit end and 3 at the shooters end...

..and left a small expansion chamber lined with acoustic foam where the muzzle sits..

The neopene facing at the shooters end is reversed to be towards the blast too.
So here it is , all closed up and with a swing-out platform for the chrony..


Does it work, after all that, you may ask? Well, early tests indicate it's my best effort yet, so I'm now feeling better about less disturbance to the neighbours (and my dear wife) as I pursue my big boring....
Next project, for this stormy weekend, my budget version of a portable shooting bench. Watch this space
Cheers from wintry New Zealand
Neil

PS Did anyone notice the muddy dog foot-prints all over the garage floor..it's been reeaaalllly wet here...

PSS Got me .50 cal back and will report soon.

Hello Neil,

Excellent job! Well thought thru. I hope it works well for you and increases your shooting time.

Now ... dragging it along on your goat hunts will require another mate or two! But, I'm sure that you'll want to be consistent whenever you shoot! haha.

Also - keep in mind a tip: If your Chrono seems erratic, if just might be too close to the muzzle wash from a big bore for a good reading. Your chamber might catch enough of the wash ... but, if not ... move it farther away. I once had a customer (an engineer) report on a Victory pistol's velocity curve. We went over it and over it ... trying to understand the curve. Turned out that two things were messing with us: 1). The printed out tape was somehow putting the shots in reverse order from which they were fired. 2). He had the chrono right up at the muzzle, and was getting oddball readings from the muzzle wash.

Good work. Glad to see your activity.

Gary

Nlei

looks good!

would offer two suggestions:

First, make the baffle spacing irregular, random, so that none of them are the same distance apart.

Second, if the acoustic material between the baffles doenst have some texture to it, add some. Cut a few holes in the foam, or pull random chunks out of each one.

Both of these change the way the "shock wave" interacts with the device, and the more it interacts with the device, the faster it gives up its energy and gets quieter....

Just a couple of things Ive learned in my own sonic signature reduction efforts........

Very nice Neil! Always nice to see an actual post on some part of the hobby!

I think you've got a neat design going there. I'll be standing by for the results of the big bore test. I may need to copy the design and place one near the back door...

Thanks guys...
Gary, I haven't worked out how to attach it to the muzzle for hunting. But I think it will need camo paint, and bicycle wheels on it to help get over rough terrain
Good advice re the chrony, I'll keep an eye out for odd results.

Dan, I should have talked to you before I made it! It is pretty much a sealed unit now as I glued the foam to the last panel when I assembled it. I did have thoughts of using egg cartons filled with expanding foam in the expansion chamber, but there wasn't really enough room so I abandoned the idea. I'll incorporate your ideas in version #7, if there is one...

Jerry, thanks, you are welcome to my detailed plans...oops, i don't have any

If your gonna put wheels on it..... go ahead and build the shooting bench and make it one mobile unit....

they have done it before ,,,lol , they are called tanks .
looks good , bet it helps a lot .

Heheheh..I was kidding about the wheels (and the paint) , this is definitely a stay-at-home device