This sounds a bit off...

They said that Graham and Fiore would meet them at the checkpoint. I don't think they're gonna walk them to the checkpoint.

Also... the feds told them to put their guns in their vehicles BEFORE going to the checkpoint. Who is to say when they leave the tent with their guns they don't get shot up?

I'm not exactly sure how far they are from the checkpoint and/or if Graham and Fiore will be able to see what is happening while they wait for them at said checkpoint.

I think they should have just agreed to leave their weapons in the tent. Unless they're planning on going out in a blaze they should give the feds NO excuses for taking them out.