I have caught Pike launching at the Carlisle / Bedford MA boat ramp, and have pulled them out as close as the bridge right there at the launch. If you take a right out of the launch and go down the river you will find large weed beds with some good change in depth abutting them, good spots to try.
I have not a had ton of luck with Pike in the Concord on artificial but have caught a few on buzz baits over the weeds. I feel like there aren't crazy #'s of Pike in the Concord, however I have caught several 8-12 lb fish and my friend pulled one out that was 20lbs. With that being said, the best action I have had there was with large shiners and suckers (perch would work well too I am sure). These were baits 5-8" long.
When fishing the rivers with live bait I like to use 80lb Seaguar Premier to tie 36" leaders with a (2/0 - 5/0) hook depending on size of bait. I have never had a pike chew through the 80lb leader and I believe it offers a touch more stealth than steel leader.
Let me know if anyone plans on hitting the river in January as I keep my boat in my garage all year ready to hit the rivers for pike!!! It really stinks there is no place to launch on the Merrimack River north of the Lawrence dam in the winter....
Picture attached of my buddy and I dodging ice chunks on the Concord in December 2019;)