Carbon shaft tuning false reading?

[inthere10x]

Shooting a Leon Stewart Slammer 52@28, drawing 28". Presently shooting gold tip (black shafts) 3555, cut 29.19", 145 grain field points, 50 grain brass inserts, 5" feathers and wraps. According to Stu spine calculator arrows spine at 53.4 and they fly like darts.
Wanted a heavier GPI, so I bought gold tip (black shaft) 5575, 50 grain inserts, 5" feathers, wraps. Presently cut to 30.5" and using 200 grain field points. Fletched flying stiff, hitting left (right handed). According to the spine calculator arrows spine at 49.0.
My question in theory if I cut the 5575 to spine in at 53.4, shouldn't they fly like the 3355 spine at 53.4? Could the 5575 be so weak the shaft giving a false stiff reading?
Wanted opinions prior to cutting the shaft shorter.

[jeanpaul3006]

I have a shorter draw lenght and had to have 300 grains up front to tune a 55/75. My 35/55 needed 175 to fly well.

[kat]

In my experience, Stu Miller's calculator may be a good starting place, but I wouldn't take it 100%.
That being said, the 5575's may need MORE weight up front. If anything, I would think the stiff reading you are getting is what I would expect.
Because they are already cut to 30.5", I would add more weight up front.

[JamesKerr]

I agree I think you are still to stiff. Try adding more weight up front.

[Tom Anderson]

Definitely need more weight up front with those 5575's.

[inthere10x]

I didn't cut all the shafts that short, what do you think of overall l of 31"?

[kat]

I use a .400" deflection carbon arrow cut to 32" long out of bows that are cut 3/16" past center.
It takes a minimum of 200 grains to keep them from being too stiff.
You have nothing to lose by trying them full length.
You can always shorten them, but making them longer just don't work.

[Tom Anderson]

FWIW, I almost always leave mine full length and tune with tip weight.  I like the extra sight plane it gives me.