I usually shoot 3 shoot groups because I don' t think I will ever get 5 shots at a deer.I have taken 2 deer at the same time twice and one was with 2 shots and one was with 3 shots ( I missed it the first time).
Yes I would send the barrel back and see if they will put a 1:28 twist barrel on.
The 1:20 barrel I got first you couldn' t hit a bull in the ass at 25 yds.The 1:28 so far shows a lot of promise,I haven' t got it fined tuned yet because of the weather but should pretty soon.