Hi wicketave, appologies for the delay, problems with this "TV with an attitude".
Don't have an authorative answer on your "w" question but I can direct you to a wealth of authorative answers. The Civilian Marksmanship Program is probably the best place for you to begin your research.
Sorry I don't know how to do those "linky thingies" and the kids don't visit till the weekend so you will have to type it in, but it will be worth it.
Go to => odcmp.com - upon arrival go to SALES. From there you can access the forums where your questions will be welcomed.
Also a very worthwhile section with which to avail yourself is the M1 CARBINE SALE section. In there you will find shooting tips, info on magazines, detailed instructions on disassembly / assembly and original "gubmint" documentation on subcontractors and their markings. You may also wish to look in on the auction where the wire stocked M1A1's show up regularly.
I do hope this is helpful. These weapons are fun to collect and increasing in interest and desirability. They are a hoot to shoot (my wife and daughter "luv 'em") and they always attract interest at the range. In my opinion they are, with appropriate ammo, hard to beat for a home / campsite defense weapon. Throw in the history of their development and the heroes that used them and what's not to admire?
Good Luck & Regards - Al