missing left

[Four2]

I had the chance to shoot in a primitive archery competition at a rendezvous last weekend.  The rules of this event precluded me using my own equipment so  I borrowed my brother's self bow and wooden arrows.   I am right handed and have a 28" draw length.  My own bow is a Toelke Whip 50#@28" and I usually shoot carbon arrows for hunting. I can regularly keep all shots inside a pie plate at 20yards with this setup.  Self bow I borrowed was 40#@30" and not cut as close to center as my Whip.  I do not know about spine on the wooden arrows but they were about 31" long.  Had all of my shots been to a single target, I would have had a great group, 8" left of my aim point. Elevation was fine, just every single shot hit 8" left of my aim point.  I have also noticed that when I miss with my Whip, it will be left as well.  Arrow flight looks good to me.
What am I doing?  Thoughts, suggestions?
Thanks in advance.

[Apex Predator]

It's in your grip and follow through more than likely.  I have to really push the bow towards the target to prevent hitting left with longbows.

[John3]

Hitting left with a fletched arrow means they are spined too high. Easy to fix, go weaker spined or add weight up front or same spine longer shaft.

John III

[Bowmania]

What JDS3 said.  Arrow doesn't have enough paradox and hits the riser making it go left.  I had this problem with a bow I use to shoot.  Took the strike plate off and use a rasp to make it more center shot.  Shot right where I was looking after that.

Bowmania

[Cherokee Scout]

If I pull my hand away from my face at release. I hit high left.

[Mark Hedges]

All of these are good suggestions but for me lately  when I start missing left the problem seems to be my stance.  If my stance is too open then I can't turn my head enough comfortably and my right eye is not right above the arrow and I miss left.  Closing my stance a little lets me turn my head enough to get my eye right in line with the arrow and I no longer miss left.

Mark

[vermonster13]

A 40@30 selfbow at your 28" draw was probably only pulling around 34#s or less. You need some seriously light spined shafts. My bet is you were over spined also.

[Four2]

My first thought was that the arrows were overspined for my length on that bow.  I also suspected that there was probably something in my form since it also sometimes happened with my own set-up.  Thanks for the help.

[TonyW]

Once you saw that you were consistently hitting 8 inches to the left, did you try picking a spot 8 inches to the right of the target to see what would happen? I know it would be better to have properly spined arrows, but wouldn't this be a jury rigged solution under field conditions?