At such low velocity, if the bore is good, I doubt that many shooters could detect a difference in accuracy between pb and gc. However square bases are super important to accuracy with short bullets like this, and bump squaring if using an RCBS, Lyman or Saeco sizer will tighten groups, sometimes dramatically. If using a Star sizer, I've obtined best base squareness with bevel base and sizing them base first, or down. Reverse that if using gas checks and use a flat punch that's close to sizer diameter so it flattens the checks while they are being sized on. (Bump square them in the other sizers, just as with pb.)
If the lube you are using gives any leading at all, a gas checked bullet will improve accuracy quite dramatically in most instances. Using LBT lube will eliminate leading for almost all ACP shooters and costs little if any more than most of the stuff sold for lube which doesn't work nearly as well.
