Broadhead tuning

[Ehunter]

Ok, I've tuned my FC400 using paper tuning, walkback tuning, and shooting at vertical and horizontal lines. It is a tack driver with both field points and broadheads. The problem I have is, I can't for the life of me get them to group together. Last night I was gettng 4 inch groups at 70 yards with broadheads. I get the same with field points. Problem is, the groups are at least 2 feet apart at that distance. Roughly 4 inches apart at 20 yards. Field points hitting to the left of the BH's. I have moved the rest left and right, VERY slowly, (1/32nd of an inch at a time), and it never improves beyond this point. I have shot heavier spined arrows, and get the same result. Any Ideas? Thanks guys!

[justin]

i would try a differnt broadhead.... ive shot 340 spine arrows with brand x 3blade fixed heads and they impacted perfectly with my feildpoints. but brand y 3 bladers were way off!! brand y hit dead center with 400 spine aarows though, and brand x was way off...... bolth 100 grain points and it seemed ther were only nominal differances in them......

[wscywabbit]

I have had fairly good success with the broadhead tuning section in the martin manual. HOWEVER, last year I tried to switch to a four blade broadhead, and they wouldn't tune for crap! Put my old muzzy 3 blades back on, and whalla. Sometimes you can tune and tune, but it won't make any difference. Good luck!

[Destroyer]

What heads?

Try a heavier field point with the same broadhead and see if they are closer.

[Ehunter]

Destroyer, the heads are Shuttle T-Locks. Are you thinking I am overspined by suggesting I shoot a heavier FP? Arrows are 28.25 inches, 350 spine (actually a 310), 70# draw@28.75 inches true draw. I'll try a heavier FP tonight, see what that gets me.
If the thing wasn't shooting such good groups with BH's, it would make more sense to me. I'll probably try shooting my Slick Tricks as well, see how they match up.

[Destroyer]

If the thing wasn't shooting such good groups with BH's

If its shooting so good then don't worry about getting the field points to hit the same spot. Is there a real need to have them hitting the same place?

Are you thinking I am overspined by suggesting I shoot a heavier FP?

Not so much overspined but a different affect on the spine depending on the type of head, that some broadheads weaken the spine a small amount in comparison to field points of the same mass weight. That's why I suggested you try a heavier field point, to change the spine of the field point arrow slightly and see if it equals up a bit. If it makes no difference then it must be something else like the aerodynamics of the head, etc.

I'm not a fan of group tuning anyway, I don't think its as easy as it use to be getting them to hit in the same place. With faster bows, shorter ATA's and much lighter arrows, its showing up some of the old methods of tuning.