Like you, I previously used a box filled with old clothes which made it quiet for back yard target practice but the box after sometime got heavy and warped, I wanted something that could also be easy to clean and save and recycle the used lead so my search lead me to the Super Target System Ballistic Target Trap. I purchased the 12x12 with 1” ballistic panel off of amazon, I also purchased a 1/2” ballistic panel and glued it to the back traps panel. I shoot my RAW HMx LRT .22 shooting 18gr @ 950fps @ 20yds and it makes a dull thud. The STS is quite expensive, 200 for box and 1” panel but it was well worth the investment to me to be able to shoot incognito in the city and recycle the lead, my RAW is quiet too. The ballistic panel is self healing. The box is rated for .22 rimfire (way over built for Airguns, weighs about 20lbs)), it is also built much more solid than my Do It All rimfire Target trap.
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