Changed My FOC and arrow diameter this year

[montanaelk31]

It was time to buy some arrows so I went ahead and bought 4mm Easton FMJs (deep six), usually I get 5 mm.  I decided to go with the new Easton Titanium Half Outsert (55 grain) so I can increase my FOC. 
So last year I was shooting 480gr FMJ 5mm 273 FPS at 8% FOC
This year I'm shooting 495gr FMJ 4mm at 270 FPS with 12% FOC


Opinions on what will help penetration the most? 4mm shafts, increased FOC, extra 15 grains of weight.  Outpenetrates my last years setup by an inch at 30 yards in a cardboard medium.  Just curious as to opinions?

 

[Boom]

nice shaft!  (i dont say that to all the guys)
i think it is a lot of things.  smaller cross section to reduce drag, and the point makes a bigger hole than the shaft, right?
i am at 13.5% FOC, and never noticed more penetration. 

did you have to move your rest up 0.5mm? 

what is the spine on those new arrows?  a 500gr arrow @ 270 fps is a hammer!!  no a tomahawk. 

 

[cohunter14]

My guess would be the shaft diameter. Less drag going through.

 

[montanaelk31]

nice shaft!  (i dont say that to all the guys)
i think it is a lot of things.  smaller cross section to reduce drag, and the point makes a bigger hole than the shaft, right?
i am at 13.5% FOC, and never noticed more penetration. 

did you have to move your rest up 0.5mm? 

what is the spine on those new arrows?  a 500gr arrow @ 270 fps is a hammer!!  no a tomahawk.

Yes the half outsert is so you can use standard broadheads and point is wider than the shaft.
I had to replace my serving and d loop at the same time so I didn?t monkey with my rest. My old arrows were 340 spine and 11.3 gpi.  New ones are 330 spine and 11.0 gpi, cut .5in shorter bc the outsert adds 3/4 inch.
I got 2 holes with my setup last year on 2 elk, so I just thought I might help myself out all I can without changing broadheads.

 

[montanaelk31]

Here they are