Midway usa sells tons of model 700 parts. They are one of the biggest sources of general gun parts both online, and catalog sales.
Remington, gun shop, e-gunparts.com
Caliber is .243, buy ammo in .243.
The sportsman 78 model Remington is the same as a Remington 700 adl, but i have yet to find whether to buy a short or long action stock for mine... so i would just go for a rem 700 adl stock
Website for gunpartscorp
The Remington Society of America has a services/parts link too but e-gunparts.com is a good place to start.
I would start with the numrich gun parts corp.They can be found on the web.
There is no model 243, you mean a model 700 in 243? Condition? Gun values are determined by condition, condition, and condition! There's also many different models of the 700 available it 243, new you can buy them from 6-800.- so less then that based on the model and condition.
Some parts at Gunparts.com can be found. Mags are hard to get.
Knesek Guns, Inc. sells the full Remington line including the USR www.KnesekGuns.com
I would say that this is a a matter of opinion,Both of these rifles are well made,and accurate.I would not hesitate to buy either.
There are 3 options,,call Remington and ask, they do not have it posted on there web site but might have it around. Buy it---http://www.gungarage.com/remingtonacc.htm Go to a gun dealer and ask, most have one for repair parts.
Check the service and parts link on the Remingon Society of America (A collectors organization) http://remingtonsociety.com/rsa/service