Pellet trap for Texan 45cal

 Hey guys. I use a cardboard box and shredded T shirts to catch pellets up to 25 cal but I recently bought a Texan 457 CF and I wanted to build a trap to catch the lead. Wondering if I could scale up to a much bigger box or if I have to get a steel trap. I don't really want to go with steel because of the sound but I will if I have to. Any other suggestions would be welcome as well. 
 
I’ve not shot a .45 into my trap. The highest power I’ve shot is a .35 at PBR.
Mine sits at the back of my Chrony stand. It’s a five-gallon bucket filled with rubber mulch with a 1/4” thick piece of polycarbonate cut to fit in the bottom of the bucket for added safety.

I’ll bet the mulch in and of itself will stop the projectile and dampen the noise of the impact as well. Prior to the bucket, I had a cardboard box about 8” square and 8” deep also filled with mulch. Never had a .35 pellet (pellets are all I shoot) penetrate the box. I went to the bucket because after repeatedly shooting into the box, it caused the box to bounce around because it wasn’t heavy enough and cardboard starts to breakdown after awhile. 
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I have another idea for a bullet trap for the Texan 457 caliber.

Using 4 foot railroad ties, I will cut each into 2 foot pieces and stack them horizontally to a height of 4 feet using 2 vertical steel poles for back support.

Then, I will place 3/8 steel plate in front at an angle of say 45 degrees to deflect the pellets down into a sand box to recover the lead.

I will get the steel poles and steel plate from the local used metal recycle yard. The total cost should not be too much using recycled metal.

The only draw back I see is portability.