Re: 700 SPS Varmint
My SPS-Varmint came with the X-Mark. Many of the newer rifles are coming with the X-Mark Pro Adjustable. I don't know when the switchover was.
The X-Mark Pro Adjustable on our AAC-SD will only adjust down to around 4lbs. with the "adjustment screw" in the trigger shoe. If I want to go lower than that I will have to actually remove the action and use the internal screw in the housing.
Remington does not recommend this for an end-user but an Armorer may do it as long as they stay in Remington's guidelines for pull weight.
I did adjust the X-Mark on my SPS-V awhile back, but it would not keep a consistent adjustment. It kept creeping heavier. It was replaced with a pre-2006 and then a Timney 510.
The trigger on the AAC-SD is heavy, but it breaks very clean. I am going to stick with it for awhile, because it is not the limiting factor in the rifles accuracy.