What material are you using to print your jigs?

i dont have a GG - but for regular milling, and anything that generates heat, ABS at a minimum.  PLA will get too hot once the milling gets going.  even with milling aluminum you will want to keep your work piece temperature under control if you use a printed fixture.

Is abs printing much different than pla?

people will tell you yes, but in reality not as much work as printing CF Nylon for example.  no special routing for the roll is needed, no special nozzles, no special print heads.  Bed temp 100, nozzle usually 235 unless otherwise noted (e.g. polymaker 255, atomic 245) - gluestick works well as the release agent, and it wants a nice close nozzle for good adhesion.  outside of that, the higher the printed part off the bed, the more you will need an enclosure.  I printed a number of AR Grips using a draft shield (see options in CURA) but an AR receiver sized fixture will both benefit from being close to the bed and also be negatively affected by the large size and possibility of colder air getting brought in.  so for that you will likely need an enclosure for your printer.  tent type are available for 70-80 bucks on amazon and work well.  the goal is for the ambient temp to be higher (like 100+ F) and consistent.   warping can be a thing but good bed adhesion is your best defense.  you will know you have the good squish on layer one when your print is done but the work piece wont come off for anything until the bed cools.  after that it should just pop off on its own.

Generally the advise for ABS is no part cooling, but if you have a larger bed and thus get a lot of heat going in the enclosure you may find running some part cooling fan to improve print quality.  CNC Kitchen did a good video on this where he generally debunked the "no part cooling" myth as long as you have an enclosure and appropriate temp.  I generally run 35-50% for ABS.