Run With The Fox,
A timney can make a big difference. I have replaced a number of stock triggers with Timneys and they usually dropped right in with the exception of one rifle that needed a little wood, and I mean a little, removed for clearance.
Couple of items... Usually the blind magazine rifles like your friends are model ADL and the ones with the Magazine Floor Plate in front of the trigger guard are model BDL (a step up from the ADL).
Another good reason for replacing the trigger is due to the issues remington had with the Safeties failing unexpectedly and all 700 have been recalled (to the best of my knowledge). They will still replace the trigger at the factory but it will not improve the pull. I called on one and by the time I paid the shipping, replacing with the basic Timney was only $25 more, kinda a no brainer. I did call Timney to ask if their trigger/safety would solve the Remington issue and they said YES!
As for date of manufacture that is determined by the 2-3 letter code on the barrel just in front of the receiver ring. First letter indicates the month, the second &/or 3rd letter(s) indicates the year of Mfg. There are a number of sites (just search google using Remington MFG Date ) and you will find a number of tables you an use to get the date.
Hope this helps...
WBLDon
