The coiled-steel snare wire is a wonderful invention and a huge improvement over, uh, animal parts. But making it happen required the simultaneous invention of the ‘end plate’ (or ‘butt plate’), and that opened up a real can of worms.
The original snares 'wires' were made of leather, usually some type of gut (intestine linings). Coupled with thin leather heads, gut snares worked well. All that was needed was a bit of relief in the rim and at the edge of the drum shell and all was well. Ordinary humidity would ensure that the head would mould itself to the snare bed, and the gut snare strands would quickly form themselves to that same contour.
With the introduction of the butt plate, the game changed completely. Because snare wires are made of metal, they must be welded or soldered to something that's strong enough to hold them (plastic was tried for a time, but soon abandoned). The butt plate is a slice of metal slightly wider than the set of wires and about 1/2-inch deep. It’s metal -- it doesn't flex. The snare wires don't flex much either, and they don't flex at all where they join the butt plate. So where you once had soft, flexible gut strands that easily conformed to the drum head, you now have two chunks of inflexible metal that sit right plunk on the snare head at both sides. And that's a problem.
In the olden days, the snare gate and snare bed combo offered just enough clearance to let the gut strands do their job. After the introduction of metal snares, the snare gate was gradually made larger over time, but the snare bed remained almost unchanged for a long time. It's common to see snare drums made quite recently that have old-style snare beds: fairly deep and only marginally wider than the snares themselves. I might mention here that plastic heads don't sit well on deep, narrow snare beds … double jeopardy.
There were some very creative attempts to solve this problem that mainly involved changing how the snares were attached to the drum. Leedy, Slingerland and a few others added cages and guides outside the snare gate at each side of the drum. The snare cords or straps travelled over the guide so they ran parallel to the snare head where they entered the snare gate, keeping the butt plates from pressing into the head. The Rogers Drum Company decided to mount the snares in a special rack that kept the butt plates off the snare head completely. This trick had a second advantage in that the tension along the snares could be adjusted separately from the up and down tension. Rogers ‘Dynasonic’ snare drums are still highly prized.
One of the more successful approaches was to run the snares all the way across the snare head and completely out each side. Drums such as the Ludwig SuperSensitive and Premier 2000 have a beam running through the drum that holds the snare mechanism and the butt plates well outside the drum head area. Of course the objective was to have a snare that could be adjusted both vertically and horizontally, but getting the butt plates off the head was also a priority.
Other solutions, and I'm sure you've seen them all, were to play around with the attachment material and/or the mounting holes in the butt plates. Rather than go into detail on the different approaches to snare strings, plastic strips and the like, let's just say that it's a mixed bag that has had mixed success.
As for the mounting holes in butt plates, some real science has gone into this, and also into the design of the butt plates themselves. Slots, channels, lifters, bends, and what have you ... who'd have thought that something as small and simple as a butt plate could have such an impact.
Some drum companies have discovered -- finally -- that an enlightened snare bed design can virtually eliminate the butt plate problem. I played about with snare beds years ago and discovered that a wide, shallow snare bed could completely negate the influence of the butt plates and plastic heads. Moreover, a well-designed snare bed can accommodate many different sizes of snare-wire sets and attachment methods. If the snare bed is cut properly, the drum will act as if the butt plates don't exist, and what you get is pure snare sound, increased response and no choking.