I recently got a new set of limbs for my samick sage. 45# and I draw 27.5 with a fast flight string from Tenring. Have the bear hair rest with included sideplate.  Arrows are GT 3555 with 50 gr. inserts, 125 gr. points, and cut to 28.75. I am having a hell of a time getting this thing shooting properly.  Paper tune is showing nock high but good spine. When I lower the nock point i get rid of the nock high but then I get a tear 6 inches to the left.  I had a little time to tinker this morning and I lowered brace height a little and that seemed to get me slightly closer.  

Also I guess samick has two different designs for their limbs. My first set just had Sage printed on the bottom limb and the second had the weight of the limbs and seemed to have less curve to them. When switching limbs I left the string the same and the brace height jumped up an inch. I have since dropped it down to 8.25.

you might be a tad stiff in the spine at that length, just a guess.

I'd also venture a bit too stiff. I have to shoot 30.5" 3555s with 200gr out of my 43# bows drawn 28".

arrow may be kicking off of the shelf? can be either too stiff? or are you plucking string on release. probably a combination of both.

I have a similar setup on the bow but different spine arrows.  I couldn't get the arrow to fly very well off the shelf.  Seemed to lose some speed, too.  I went to a cheap, plastic Hoyt rest and that seems to work fairly well for me.  Drawn to 26.5", I get good flight from GT Traditional 400s, cut to 29", 200 gr heads & 50 gr inserts.  Oddly, feather orientation wasn't an issue with 175 gr broadheads, even though the flight was a bit off.  With 200 gr broadheads, suddenly the feather orientation mattered a ton.  Go figure.

I'm playing around with some full-length 340s with the same heads/inserts and drawn to about 27".  They bareshaft a bit stiff but they're impacting the same out to 20 yards and a few inches left at 25 yards.  Fletched are grouping well.

I would think you are to stiff as well, I would think you could make the 3555 work, but only if you left it long.

Until I started shooting carbons full length I never could get them to tune right...Try full length and then adjust spine by point weight and you should find them easier to tune...

try some 175gr. tips and be sure your nocks are fitting the string properly.

heck i would go up to 250 gr points that might fix it for you