CHAMP198

i have been messin around with BH tuning here lately and cant get them to group the same as my FP.....shooting a Bowtech 101st Airborne at 65lbs with 300 Spine Victory HVs at 28.5" with Slick trick 100 Mags and a release......had some 340 Axis Nanos and thought they were too weak spined so got the victorys and still cant get them where they need to be.......messed around with it some last night andwhen imoved the rest the wayi wanted to get my BHs to move to get the same POI as the FPs i cant get it the same.....from what i have seen and also done before if they are impacting to the right of the FPs move the rest to the left to bring the BHs over to the FPs......with mine i have them within 3" to the right....when i started they were about 6" right and i had to move my rest ot the right to get them where they are now....im just kind of lost.....my Ross i had shooting perfect with BHs and FPs in the same spot within 15 shots but i cant get this one right.....i have had people tell me i am way over spined but i checked my arrows with the OnTarget program i have and it said the 300s were right on...so im really lost now...some guys are tellin me to use a 400 spine...and that seems way to weak.....anyone have any advise??? Dan??? Greg??? im about to pull the little bit of hair i got left out with this thing [/align]

kwilson16

Some of the software guys can tell you if your spinelooks good.

You can also try a lighter/heavier point to strenghten or weaken dynamic spine. I keep a 125 and 75 grain field point on hand to experiment with differig weights if I suspect spine issues.

Or, you can adjust draw weight to verify your proximity to spine limits. This can revealif you areclose the limit of spine.

Have a friend shoot the bow to see if you are introducing hand torque. I know you might not want to hear that but it is something to consider.

How much are you moving the rest? Just a tiny adjustment can make big differences.

MeanV2

IMOyou'll find most charts and programs veer toward the stiff side. I tuned my 70# Allegiance with CX Maxima 250's and they flew like darts and ST's grouped right with FP's out to 60 yards. Most guys would tell you those arrows were underspined but not so.

The 250's are on the verge of being too stiff for my 60# bows but not enough to affect my groups or flight. Another thing you might check is FOC. I try to stay at least with 12% for Broadheads, preferably even higher.

One other thing I've noticed is Binary Cams tend to prefer a softer spine than say a Single Cam

Dan

mez

What year 101? If an 08 have you adjusted or changed the factory string stop?

MeanV2

BowTechonly made the 101st in 08. Changing the rubber insert or adding a lower mount suppressor or both can help with tuning issues.

Dan

OHbowhntr

You should be using a 400 spine arrow, with a 125gr tip, cut at whatever lenght you find isappropriate. With my 71-72# set-up pulling just a hair over 29", I'm shooting 340 arrows at 29.5" with 125 grST Mags, andI'm just a tiny bit overspined. Not enough to show, as I'm getting great groupings, and I have FP's and BH's comfortablyclose to each other all the way outto 50yds. If theFP's and BH's are hittingtogether yet, I keep moving the rest, but if you get to the point that it just seems impossible, then you need to be looking at the spine.For your set-up, I've plotted those numbers for a couple guys on almost the same spec's as you, and they needed 400 spines, not 300 spines, and both were set-up with 125gr points as well. Remember a better FOC will allow the BH to lead that arrow, and the fletches to guide it. Think about throwing a plastic dart like you use for those electronicgames, then throwing a "REAL" dart, which one flies better!!!! If those are a 9 + gpi arrow, not sure which Victory HV arrows you have, but if they are a 9-ish GPI, your FOC is only in the 8%-ish range, get it up in the 11-12% range, and you'll have better arrow flight as well. But a change in the shaft would certainly be in order from what I know. (Which really ain't very much.)

JeffB

Cam lean can cause these issues as well

While 400s may work, I think a 340 spine is the safer bet with fixed blade heads. IME- most of the software programs really like to overspine- ridiculously so in many cases.

I would start all over from scratch with the 340s and ditch the stock suppressor for a lower mount version.

ijimmy

I agree with Jeff 400s are too weak , 340s are about right for your spec's

first thing I look for is vane contact , that really screws up broadhead equipped arrows , if you shoot feathers , disregard

try some other arrows , though I have yet to find a better shaft than axis , I shoot the fmj variety

JNTURK

Vane contact...cam lean....bow torque....any of these are possible causes of your problem......also, the amount you should be moving your rest while shooting 20yds should only be in about 1/16th adjustments...

note: even with a perfectly tunned bow and steady arm and great arrows ... sometimes some broadheads just won't fly spot on with FP's (but should be closer than 3")