There are no regulations for shooting steel targets at official ranges, not in Ontario or elsewhere. Ontario and BC CFOs have issued separate guidances with regards to steel targets that are not official, other than as a fiat that gun clubs disregard at their peril. I have not seen any official communication of these, but they are widely circulated second hand.
The RCMP Range Design Guide, which is not scientific or authoritative in its musings on range design, is often invoked by the CFO in support of their demands with regards to steel target use, however these demands are largely unsupported by the design guide itself.
It says this about steel targets.
If hard material targets (e.g. steel targets) are used:
The range users must be aware of the minimum safe firing distance from these targets. Firing at distances less than the safe limit will expose shooters to the risk of injury from bullet backsplash; refer to section 1.9 Backsplash;
The targets shall not have a design style (e.g. concave) that will direct ricochets or backsplash towards the shooters; and,
It is recommended that the targets be of a flat steel design, constructed of materials of sufficient hardness, so that they do not significantly crater from bullet impacts. Refer to section 9.6 Bullet Traps for information about steel specifications for indoor range backstops. This information can be applied to steel target specifications.
Backsplash as it relates to targets and minimum safe distance per section 1.9
1.9 BACKSPLASH
Backsplash is defined as fragmented bullet or target materials, or ground debris, thrown back towards the shooter as a result of bullet (or projectile) impact.
To protect shooters from hazardous backsplash, it is recommended that the minimum firing distance not be less than the distances shown in Table 1: Recommended Minimum Engagement Distances (Backsplash).
Table 1: Recommended Minimum Engagement Distances (Backsplash)
Calibre Class----------Hard Target-----Ground Impact
Rim-fire---------------10 m-------------10 m
Centre-fire Handgun--10 m------------10 m
Centre-fire Rifle-------50 m-------------25 m
It is generally considered good practice for shooters and range staff to wear impact-resistant eye protection (e.g. shooting/safety glasses) at all times. Anytime that target backsplash is likely, it is strongly recommended that shooters and range staff wear impact resistant eye protection.
With regards target construction per section 9.6 steel specifications for backstops, as it relates to steel targets:
Exposed screw heads/bolts must be flush with the steel plating; If authors of the design guide had any experience with manufacturing at all, theyw would have required bolts to be of similar grade and hardness to the steel plate
Bolt nuts should not be exposed to projectile impact;
Steel plates must be adequately supported to ensure that they do not buckle, bow or waver as a result of their own weight or sustained use; and, It is debatable if hanging targets by chains that permit free movement of the target meets this guideline
Edges of steel plates exposed to direct bullet impact shall be bevelled and have a fillet radius of no more than 1.5 mm.
The design guide contains a chart indicating minimum steel thickness based on calibre and bullet construction that is unscientific, and probably never independently validated by the RCMP.
In general, for handgun calibres up to 50 AE, 10mm (3/8") AR 500 steel is required, or 12mm (1/2" of mild steel). The guide allows for substitution of equivalent materials, however no formulas are given for determining the relationship between material thickness and hardness, and its resulting ability to resist penetration. HINT, its not linear, and each substitution would need to be independently validated by ballistic experimentation.
Note that this schedule of material thicknesses is listed for bullet traps with a minimum angle of 45 degrees from angle of impact. In order for these thicknesses to be relevant to a steel target application, targets would have to be placed at a 45 degree angle and fixed rigidly in place to guarantee all impacts hit at the same angle, yet Ontario CFO requires only 10 degrees and BC CFO requires 20, and both permit the plates to swing freely which permits completely random angle of impacts if the plate is engaged while swinging (which is kind of the point).
Spread throughout the guide are a incoherent list of requirements offered without substantiation or explanation. SUch as:
The use of unsheltered Hard (steel) targets on baffled ranges is not permitted.
The use of hard targets (steel) on an indoor range should be closely monitored by the Range Operator. Bewildering that indoor ranges, which predominantly use baffles for ballistic containment, are not given the same treatment as outdoor baffled ranges
The courses-of-fire using hard targets should be critically evaluated by the Range Operator to ensure that the range users and those exterior to the range are not put at risk as a result of the inappropriate use (e.g. placement, type and design) of these targets, given the range design.
NO explanation or qualification is given to substantiate what particular range design features influence the permitted use of steel targets. Nor does it draw a distinction between the risks of appropriate use vs inappropriate use, in relation to persons outside of the range.
There is an illustration titled Figure 47 Steel Target Revetments, shows a bunker built into an earth berm with a box made out of railway ties. There is no description or supporting design requirements for this figure. It is an orphan picture in the midst of the section regarding Side Berm Construction. Nothing in the guide describes a temporary shroud as required by ON CFO, and only imagines permanently emplaced bunkers.
Hope this helps.