Black Widow PL V draw weight question

[sendero25]

I just received a new to me, 64" Black Widow PL V longbow and my question is this:
It is marked 50# @ 29", I know Black Widow measures their draw length from the front of the shelf instead of the center of the rest or the rear, so what is my draw weight at 27-27.5"?
My local shop is closed this weekend so I can't get to a scale until later this week. Thanks for the help! It feels only slightly weaker tham my 50#@28" Martin Serengeti
John

[J.Williams]

Most all glass bows gain/lose 2.5-3lbs. for inch of draw weight so your bow will be about 44-46lbs. at your 27-27.5" draw length.
It is common for Martin bows to run a little heavier than marked but it could also be a design difference between your bows that makes the Martin feel heavier.

[sendero25]

Thanks J. That is about what I calculated but a little confusing with the widow being measured from the front of the shelf instead of the center or rear as some other bows are.
Thanks again,
John

[bigcountry]

I think they rate your draw length as not your true draw from you grip to your string but from the back to the string.  Same as with martin or most manufactures.  I see a 2lb at least loss in poundage per inch drop.