I believe I have seen an official statement about the # sign in relationship to draw weights printed on Bear recurve bows but at the moment I cannot put my hands on that information. However, my recollection is there is NO TRUTH to the idea that Bear uses one or more X marks either before or after the draw weight printed on the bow to signify a higher or lower draw weight by one pound increments. Here is why.
The recurves manufactured at that time were "hand lettered" on the riser with the serial number, length, and draw weight. This lettering was done before the final coats of finish were applied. Data sources such as the "Traditional Bowyers Encyclopedia" describe the manufacturing process for this era of Bear recurve bows in great detail. (Lots of fascinating reading material in that book!)
Generally, bows were manufactured in several standard draw weights for most recurve models. The encyclopedia even lists the tables of available draw weights for some models. No efforts were made to test each and every bow to determine its specific draw weight, as that would be a cumbersome process requiring stringing each bow, setting brace height to specs, establishing a nocking point, and then testing each bow with standardized equipment to determine whether it was a pound or two more or less in draw weight. Then the entire process would have to be reversed so the bow could be packed unstrung with an unopened new string, etc. before being wrapped for sale. By using extremely good manufacturing techniques such as cutting wood for both sides of the limbs in pairs from the same piece of hardwood, Bear Archery made bows that were within the tolerances set by the AMO standards of that day without having to test each and every bow to determine its individual draw weight.
There was another reasons why bows were not individually tested beyond the extra manufacturing time consumed to do so while making the bow. That is because the draw weight on a recurve bow varies by the length of the draw!! In general, for each inch of draw an archer has which is greater or less than the standard 28" draw length the draw weight either increases or decreases by 2 to 3 pounds. So, a bow that is precisely 50# at 28" would shoot 52# or 53# at 29 inches and 48# or 47# at 27 inches of draw. No manufacturer can know what draw length the end user will have so it is simply not worth making an excessive effort in mass production bow manufacturing to test and state the draw weight with extreme precision.
That said, custom archery shops can and will build a bow that will shoot a specific draw weight for any given archer. Thus if a smaller archer draws only 26 1/2" inches but wants to shoot a 50# recurve bow, any good custom archery shop can construct such a bow matched for that shooter.
One final thing that also easily proves the rumor of X before or X after the draw weight in precise one pound increments is false is the obvious application of "common sense." If Bear Archery did test each bow to determine its actual draw weight, since they "hand lettered" all the information on each bow, why would they not just write the correct draw weight, if known, directly on the bow? It makes no common sense to write X50 on a 48 pound bow when you could MORE easily simply write "48" if you actually know the exact draw weight.
Like most stuff, I believe that is just folklore that has circulated since the day about 41 years ago when I first bought my Bear Kodiak Magnum recurve. I am confident Bear Archery simply did not intend for the X to mean one pound. So a 50X labeled bow does not necessarily mean it has a 51 pound draw weight. The X probably DOES however signify that Bear believes the bow has MORE than a 50 pound draw weight, but they are not making any claim of exactly how much more.
For those who are interested in traditional archery, here is a good link to a page that gives a lot of useful details regarding dating an early Bear bow. http://www.neoreality.com/archery/beargray.htm
Bows like mine which were manufactured in the 1964-1969 era can be dated to the year of manufacture by looking at the first digit of the serial number. The "8" on my bow indicates it is a 1968 model. Bows like your newly acquired one should start with the letter "K" if they were manufactured in the 1970's. There are some other things that help date bows such as the "coin medallions" on the bows or the materials used in the bow construction.
Congratulations on getting a fine bow!! I know you will enjoy it greatly.
PS> I cannot be sure from the photos alone, but it looks like the Bear medallion on the riser is the nickle-silver one used on Bear bows manufactured in 1971 and for a portion of 1972. Your bow is not a 1970 model, as the Bear medallions were brass that year. Likewise it was not made in late 1972, as Bear started using plastic medallions that were above the bow surface.
The serial number is a "K" series which is consistent with the 1971-72 period of manufacture. And the riser appears from the photos to be the "impregnated maple" used in that period, also known as "future wood." The limbs are fiberglas laminated.
Your bow looks to be in great shape, but you will find that a Bear bow of this age and type are extremely durable and rugged. With sensible use and care, it may well last the remainder of your life. Maintenance is minimal to these bows and they are impervious to any and all normal weather conditions but extreme cold and heat can affect them.
Do be careful how you string and unstring this bow. I never use a "step through" method nor any stringer aid. Those methods make it easier to warp a limb accidentally. Once warped, getting one back to shape may not be easy to do.
I string my bow using the "pull up riser, push string into notch" method. To accomplish this, (if right handed) grip the bow riser with your right hand with the face of the riser pointing up. Put the lower tip of the bow under the insole of your right foot. Be sure it is seated well under your foot and hold your foot steady. Avoid stepping on the tip; just hook it under your instep to hold it in place. The upward pressure on the bow as it is strung will pull that tip into your insole.
Slide your left hand just below the loop of the bowstring on the upper limb and push the string up as you pull the riser straight up with your right hand. You will also be pushing down on the upper limb with the palm of your left hand as your fingers slide the string up. It will require you to be able to exert a considerable amount of force as will need to achieve about 8 to 9 inches of bend in the limbs in order to seat the bowstring in the upper notch. Check carefully to be sure the bowstring is well seated in both the upper and lower notches before drawing the bow. If not, reseat the bowstring properly.
To unstring, simply reverse the process. This method puts equal pressure on both limbs but avoids the limb "twisting" that can sometimes occur with step through string methods or using some string aids. With this method, there is never any sideways pressure exerted on the limbs so they cannot be accidentally twisted. This is an "old school" method not normally used by most people today but it really is the best way to string any recurve.