Ben- Numbers were used to designate limb lengths with no. 1 being the shortes and 3 being longest. A,B, and C were used to indicate riser lengt with A being shortest- A riser + #1 limbs equals 56" bow. The A and B risers have a four inch varience. Style I indicates the first marketed design of the riser and features a flared heel, a raised finger pad, and more bulk overall. The StyleII is a slimmer design with a tapered heel, usually a built in springsteel pressure plate (other options were available)a lower shelf, and a concave area on the offside where the raised finger pad was on the styleI and which created the "S" shaped handle. The mag riser is more similar to the style II except that it lacks the dramatic S curve of the handle/grip section. The Style I was in production from '69 through '70 and the StyleII was introduced in '71. There are other minute differences and a wide array of varieations plus Bear's custom shop created several "one-of-a-kinds", especially in the C riser target bows. The locator pin head size changed at time and varied between .050 and .060 head diameter but I've never seen fitting issues between Bear products with the exception of the Signature series limbs in which some of the limb locator pin holes were so shallow that the limb wedges split out when the bow was shot. I personally saw this happen with four sets of limbs in the early 80's. Some limb/riser combos may fit more tightly than others and some may rattle a bit when the bow is unstrung, however, once tension is introduced by stringing the bow it becomes a non-issue. Did I answer any of your questions? Good luck, Grant