Stickman,
The Ell marking is a revision number for the part itself that appears to have been applied during the time of forging on this particular piece. Revision numbers identify any engineering or manufacturing changes made to a particular part and are a way to identify them at a later date if any problems are encountered. M1 Garands are excellent examples of this practice as can be witnessed by field stripping any M1 and deciphering its history or "correctness" by the drawing numbers applied to it's components.
In contrast, very few drawing or revision numbers will be found on an M16 with the exception of the Hammer and Trigger. Other parts are usually only marked with a letter used to identify the manufacturer. I.E. Bolts with MPC(Colt) or MPF(FN) or the CMP, FNMI or EMP found on barrels, etc. M16 and A1 hammers and triggers are usually encountered with numbers to identify the revision such as 1, 2, 3 or 4 on them sometimes in conjuction with a C to identify them as colt produced parts. M16A2 components may contain the drawing type or size being E and the revision number to that drawing, in your case being the ll. Also, most of these components will have a letter near the revision number, or somewhere else on the piece to identify the manufacturer. An example of this, would be a hammer found on a Colt produced M16A2, CEl or C(Colt) E(drawing type/size) l(1st revision). These are some others I have encountered to help show the practice:
CEl - Colt production revision 1
CEll - Colt production revision 2(not 11)
El or Ell - found intermixed in mid-production of Colt M16A2 rifles some with or without a "N" marking followed by:
E3
N - National Aerospace production revision 3
E4
N - National Aerospace production revision 4
E3 and E4, N marked hammers and triggers were used as original components in later Colt production M16A2 rifles.
FN production started at revision 3 or:
E3
F - FN production revision 3
E4
F - FN production revision 4
There are some others including E(EMCO) marked revision 3 and 4 as well as others with only a letter to identify the manufacturer such as M(yet to be identified).
Back to your hammer, from the Ell marking and as shamayim pointed out the wide disconnector notch, it started out life as a blank for a M16A2 hammer. It sounds like it may have been a manufacturers reject before it was completed or the blank was sold and machined incorrectly later. If it was a completed A2 hammer the right side "leg" where the hammer spring fits over, would be machined smoothly and to a different diameter than the left side to accommodate the burst cam. However, late production full auto M16A1 repair parts, M16A3 and M4A1 hammers are made using the A2/A4 blank with the wide disconnector hook.
Yours looks like the hammer pin hole is not drilled concentric with the left "leg"of the blank which may be throwing off the geometry between the hammer nose and the disconnector. The hammer notch also doesn't look right in the picture.
BTW, the only A2 hammers that were recalled by the government were those marked with the letter H to identify the manufacturer. As of this date I have not determined who H was.
Wpns Man