There are three main factors that can reduce your draw length when switching to a straight handle longbow from a pistol grip recurve.
1. When shooting with a low wrist/flat hand, you will not be pushing the bow handle towards the target as far as when shooting high wrist.
2. Standard AMO measurement of draw length is 1.75" beyond the handle pivot point back to the nock groove. This gives an apple to apple comparison between different bows. But in reality, the important measurement for a given archer is the measurement from the far side of the arrow shelf to the nock groove. When shooting a small handle longbow the depth of the bow handle thru the shelf area can be half as much as modern recurve, so you are not pushing as much handle towards the target.
3. If you adapt to a relaxed natural elbow bend vs a straight arm locked elbow, you will further reduce the distance you push the handle to the target.
In total combination, if you switch from using a high wrist-straight arm technique on a modern recurve to using a low wrist-natural bent arm technique on a straight longbow, you could see as much as a 2-3inch reduction in draw length measured to the far side of the shelf.
One of the oldest charts used for estimating longbow draw length using all three factors above, is as such:
- to have a draw length 30inch or greater, you'd need an arm span measurement of 78inches or greater.
- to have a draw length of 28-29inches, you'd need an arm span of 75-77inches.
- to have a draw length of 27-28inches, you'd need an arm span of 72-74inches.
- to have a draw length of 26-27inches, you'd need an arm span of 69-71inches.
- to have a draw length of 25-26inches, you'd need an arm span of 66-68inches.
I have a measured arm span of 73inches. When I shoot a small handle Howard Hill bow using all three factors above, my measured draw length at the shelf is 27 1/2inches. When I compare this to the old chart, I'm dead on the money. When I use Howard Hill's method of measuring draw length with an arrow shaft, this also measures dead on the money 27 1/2inches. When I switch to my pistol grip recurve using straight arm, I draw over 29inches.
Hope this helps,
Daddy Bear