Part of Metal Type’s Printing Advice section, here Phil discusses cutting steel rule.
I cut both steel rule and brass rule on my Rouse cutter all the time. Cutting brass is easy and as far as I can tell requires no more strength of arm or machine than cutting lead.
Whatever steel rule that I cut is always 2pt rule and I use the cutting edge nearest to the hinge of my Rouse cutter. I have never attempted to cut any steel rule thicker than 2pt on this machine.
I do happen to have a 12 inch wide heavy duty plate shear. This shear was made to cut zinc plates up to a full 12 inch wide. This machine will cut six point steel rule with ease. The drawback is that there is no precision gauge to use for length. I have to manually measure the length that I want and mark with either a lead pencil or a coloured felt marking pen. A bit awkward, but with care good and accurate results can be obtained.
Tinsnips
I also have wide variety of hand held tinsnips. These also work well on 2pt rule, but as I am now old, my hand grip was not what it once was, and so I no longer use this method.
I also have 15 amp, 16 inch in diameter steel cutting power cut off saw. I have used this saw a lot to cut angle iron to build my many steel shelves and work tables and this machine is easy to use for that purpose. It makes a good and largely burr free cut on steel rule; however there is no precision gauge and the clamping device is cumbersome to use, as it was made for much larger pieces of steel. But it does work and cuts steel rule as easy as can be.
The speciality steel rule cutters as referred to by Dave Seat, work well and are easy to operate and make a good and proper cut. I seem to remember that these cutters have a capacity of up to 4pt. And if you can find a used one, well the price is usually rather more than a standard Rouse lead cutter. And new, well forget that. The price of a new cutter is only for those with deep pockets. The last catalogue price that I saw was over 1000.00 U.S. plus shipment.
I know of one fellow who purchased a metal cutting blade (essentially a grinding wheel, but very thin) for his wood cutting table saw and regularly cuts bolt together steel shelving to smaller sizes.
So, do what you will. There is no right or wrong way here. There is/are easier and more accurate and more convenient ways, but if it works for you then well and fine. Argueing with success is futile.