At the EG range we use steel backers for 22 rf shooting at 100 and 50 yrds.  As I recall Ed Cooksey made up the proto-type some years ago when we started the 22 only matches.  maybe he has the plans or someone else has a close up picture.  I just checked my photo files and I don't have any. ( A description and/ or plans might make a useful article in the Journal)

 They are a shallow steel channel, maybe 2 inches deep and 24" wide and about 4 feet long. I haven't made measurements and have no idea what the gauge is. 
These backers must weigh about 75 pounds. putting up and taking down all 30 of them for our Spring and Fall 22-only matches is a job---thank goodness the guys pitch in.

Hinged from the top is a wooden frame that fits snugly inside the channel--width wise.  the wooden frame  (made of nominally 2x2 material, 2 sides, a top, and a bottom) is pinned or bolted to the steel through the steel on the upper edges. the top is rounded so the wooden frame can fold into the channel for flat storage. they are just long enough to allow the wood to stand vertical and the steel to slope to the ground. 

The wooden frame is covered with 2x2 ft sheet of core-plast. ( a plastic sign product that looks like cardboard.) we also us it for our 200 yrd backers
When unfolded the wooden frame is vertical and the metal back slopes all the way to the ground.  Targets are stapled to the coreplast faces.

In a weekend these backers can be stopping up to a thousand or more shots. the core plast has lasted very well.  We've only replaced a few sheets and  wooden frames.  at the end of the match the ground at the bottom edge of the steel backer is pretty chewed up.  I suppose one could put a sandtray to catch the bullets.  I've never noticed splashback and the sides seem to contain  splatter.

for personal use they could be scaled down a bit I imagine