There are a few answers to this question, but first before we get into specifics I’d like to say that the range makes the rules. They’re the ones allowing us to shoot at their facility, they clean it up, maintain the backstop and have to deal with insurance companies that label them as high-risk entities. So first and foremost it’s important that we respect the rules of the range.
Most ranges state they won’t allow steel cased or steel jacketed ammunition, but this also goes without saying they don’t allow incendiary ammunition either because of the enormous risk of causing an indoor fire (1, Above Image). Another reason is these rounds cause damage to the range. In order to combat this many ranges will deny the use of these rounds, and double check them by running a magnet over the box and simply by denying certain brands. There a few reasons for this:
Rifle rounds .223 Remington, 5.56mm, and 7.62x39mm can penetrate ¼ inch of mild steel. Lower caliber handgun rounds may not damage the backstop, but with repetition they can cause damage over time. A common backstop is AR500 steel, which once it’s damaged cannot be repaired and must be replaced. At a cost of $40 per square foot for the material the cost can add up, not to mention the labor(2,3).
As stated above, steel on steel can cause damage. Friction is another key concern because the steel can cause sparks that may ignite other nearby materials. This is not that common but there have been ranges that have burnt down because of fires. Fire caused by ammunition is a lot easier than you might think (4).
Resale for Reload
Most people that go to the gun range fire their ammunition leaving their casings on the ground. Gun ranges can take advantage of this opportunity to sell them to people who reload their own ammunition into those spend cartridges.
There might be more reasons why a range won’t allow steel ammunition, but the key message from these types of rules are to keep the range operational and keep people safe from the dangers of firing a handgun inside a building.
(1) New, Brian (2013). Dallas Fire-Rescue Battles 4-Alarm Fire at Gun Range. CBS DFW. Retrieved from http://dfw.cbslocal.com/2013/02/24/dallas-battling-4-alarm-fire-at-gun-range/
(2) Leeco Steel, (2012). AR500/500F Steel Plate. Leeco Steel, O’Neil Industrial Metals Group. Retrieved from http://www.leecosteel.com/ar500-500f-steel-plate.html
(3) Chapel Steel, (2015). AR500/AR500F Alloy and Abrasion Resistant Steel. Chapel Steel. Retrieved from http://www.chapelsteel.com/ar500-ar500f.html
(4) Finney, Mark A.; Maynard, Trevor B.; McAllister, Sara S.; Grob, Ian J. (2013). A study of ignition by rifle bullets. Res. Pap. RMRS-RP-104. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 3. Retrieved from http://www.fs.fed.us/rm/pubs/rmrs_rp104.pdf