I have a few spots where I can practise shooting out to some considerable ranges but I don't like to do it too often as it can draw unwanted attention, (thinking it is poachers shooting over my land)

I was thinkning of making up some kind of tunnel to shoot through that would dampen the sound at least so it doesn't carry so well.

How long and of what diameter would it need to be, and lined with what material?
I was thinking foam or egg arton, maybe with the same foil/foam that is used for the engine bay on boats as a backing to a supplementary layer of egg carton.

The tube doesn't need to be very portable, but at least transportable.

Best I've observed is a bunch of tires stood up and held together horisontally in a wood frame on top of a small trailer frame which makes it "transportable" and moveable. The guy had about 10' of tires lined up. I was later told he stuffed them with house insulation which further dampened the noise. The most expensive part was the trailer frame. It enabled him to raise and lower the tongue to adjust for his target and chronograph. A piece of piece of plywood with a hole just large enough to put the muzzle through and enable sighting, dampened noise significantly for the shooter.

Our great gun writer and author, Rick Jamison, had one shown in a article he did some 10 years ago,(about the time I quit reading him and cancelled my subscription to Shooting Times,)which he had outside his very nice gun room. As best I recall it was made out of plywood. Boxes of sorts, which had baffles similar to an automotive muffler. It too was insulated. I recall a remark in there that the insulation did or could gather unburned powder and had to be cleaned periodically. The tire trick seemed much better to me as you could hose those off with little or no water damage.

maybe an insulated ac duct would work. That would be light weight and you could just build a frame out of 2x4s to sit it on. Have a good day, Rojelio

Ken Waters made up such a device. It would be good to know what was done so as not to have to invent it all over again.

One of are resident Canadians went through this sometime last year (was it last year?). All I remember was that he was in the Yukon, and used it to keep the kids from waking up when he shot wolves off his back yard.

Wish I had problems like that...... LOL!

Anyway, if you do a search, you might find it. IIRC, he used rolled chicken wire with foam insulation, and it worked well.

One thing, if you shoot a lot, there will be an accumulation of gun powder in the bottom of the thing, and some subsequent shot could easily light it. FWIW, Dutch.