what kind of distance are you shooting at?
is this for hunting, shooting long distance or what?
What I'd look at, is you present load accurate...
do you need that extra 150 to 200 fps real bad?
if hunting game at 200 yds or less, a click or two up in elevation, will compensate for that lost velocity...
have you made a dummy round, to see how long your throat is?
if so, did you think you are seating your bullet too deep in the case?
for some reason, you haven't mistaken a large pistol primer for a large rifle primer....seem it done... being the guilty party...
powder contamination? have a different container of 4350 you could try? to compare with?
do you have 140 grain ballistic tips, mixed in with some 120s in the box... what you are getting are 140 grain speeds with 4350...
since I've had a lot of experience in load bench screw ups... these are some of the things I usually check for...
if it were me, I'd chronograph where I am at and go hunting or go shooting...
sometimes Its not worth the effort, to try and chase down Snafus....