M3 is one of the top tier globular clusters for northern hemisphere observers. After satiating your sense of wonder with this magnificent cluster, there are some doubles worth exploring that north-south front line this globular to the west.
First up directly west of the cluster by a degree is HJ 3341, a triple with the dim magnitudes of 10.84, 11.05, and 12.48. The near equal in magnitude A and B stars are close at 2.4", requiring 200X for a good view in my 20cm reflector. The 12th magnitude C star is a luxury at 119.4". I saw the colors as white, white, and reddish, with an additional 11th magnitude companion sp the trio.
To the north of HJ 3341 is HDS 1913. This is a category of double I observe for the surrounding scenery, with no expectation of resolution. A 13.71 mag B star only 2.4" from the 10.13 mag A star is beyond my telescope's capabilities. If you have the aperture muscle to wrestle apart this physical pair, I expect that you will employ a much higher magnification than the 143X I used to view the reddish-white primary.
Anchoring the front line on the north is an easement of effort. STF 1766 is a colorful pair of pale orange and lilac, easily split at 40X with a separation of 20.2". The magnitudes of 9.38, 10.79 may warrant a higher power for a better view, however. Struve did not record any colors for this double, but with a G8V primary, I believe you will note some shades in the stars.
Returning to M3, we turn SW to a double without a designation which nevertheless has a name - BZ Bootes at 13h 38.4m +27° 17'. This 8th magnitude, deltaSct type variable looks like a double to me, even if it does not appear in the WDS. At 143X, I estimated the 11th magnitude comes at 20", P.A. 30°. I'm assuming the optical "B" star's bluish tint inspires a blush of orange color contrast to the A5 variable.
Deviating the N-S front line one degree westward from BZ Bootes, is STF 1759 in Coma Berenices. Because of the 11.22 magnitude of the secondary, 167X gave the best view of the 10.4" double. The 9.87 primary was reddish, with the secondary bluish.
Re-establishing the line south with one click of the Struve count is STF 1760. Struve saw this easy double as both white. The 8.77 mag F2 primary I saw as yellow-white, with the 9.12 mag secondary 8.7" distant as bluish at 167X.
And that completes the double star front line guarding M3's western flank. It is certainly fortunate that the riches of M3 has a patrol of resolute and resolvable doubles on watch to be reviewed. 
