An offer to help

[croix]

i'm having a hard time getting broadheads tuned and think i may be at the edge of my recommended spine.

'09 Hoyt AM32
~72 lbs (limbs are maxed)
28" draw

arrows are the 400 spine full metal jackets cut to 27.25"
100 gr. montec broadhead
4" vanes

thanks

Your recommended spine is .328", so your 400's are weak, like you thought.  Drop to 60#, and the recommended spine is .377", so the 400's would be a lot closer.  Maybe borrow a buddy's 340's to try for a while to decide if you want to go to them or drop the poundage.

wow! i would have never guessed something so stiff as a .328 until i was drawing more like 80 #. i guess that just illustrates how much fudge factor is in the easton charts. good to know.

what if i went to an 85 grn broadhead? does that get me close to the .400 spines that i have?

[doekillrssuck]

thanks for looking at my specs. and doing your thing.. v

[Todd_ID]

i'm having a hard time getting broadheads tuned and think i may be at the edge of my recommended spine.

'09 Hoyt AM32
~72 lbs (limbs are maxed)
28" draw

arrows are the 400 spine full metal jackets cut to 27.25"
100 gr. montec broadhead
4" vanes

thanks

Your recommended spine is .328", so your 400's are weak, like you thought.  Drop to 60#, and the recommended spine is .377", so the 400's would be a lot closer.  Maybe borrow a buddy's 340's to try for a while to decide if you want to go to them or drop the poundage.

wow! i would have never guessed something so stiff as a .328 until i was drawing more like 80 #. i guess that just illustrates how much fudge factor is in the easton charts. good to know.

what if i went to an 85 grn broadhead? does that get me close to the .400 spines that i have?

That gets you to a recommended spine of .338".  Try going to 65# and trying that.  The recommended spine then is .353", so that's closer.  Find a happy medium between my program and the Easton charts, and you should be fine.

[mallard79]

This is an awesome thing you are doing Todd.
What can you tell me about my set ups?

2008 Diamond Rock, 70#, 29" draw, 29 1/2" (340 spined) Cabelas Stalker Extremes with 3 blazer vanes,  100 grain 3 blade Muzzy's


Not sure of the year....PSE Nova, 60#, 28 1/2" draw, 29 1/2" Gold Tip Pro Hunter 5575's with 4" vanes, 100 grain 3 blade Muzzy's

Also if you could run the number for both bows at 5# less (65 and 55) draw weight I would appreciate it.

Thanks again for what you are doing!!    I owe you one

[Todd_ID]

This is an awesome thing you are doing Todd.
What can you tell me about my set ups?

2008 Diamond Rock, 70#, 29" draw, 29 1/2" (340 spined) Cabelas Stalker Extremes with 3 blazer vanes,  100 grain 3 blade Muzzy's


Not sure of the year....PSE Nova, 60#, 28 1/2" draw, 29 1/2" Gold Tip Pro Hunter 5575's with 4" vanes, 100 grain 3 blade Muzzy's

Also if you could run the number for both bows at 5# less (65 and 55) draw weight I would appreciate it.

Thanks again for what you are doing!!    I owe you one

No problem.
For the Diamond at 70#: I guessed that you're using the 65/80 arrows (they're .320" spined).  It shows a recommended spine of .321", 284 fps, 405 gr arrow, 5.79 gr/lb (oops!), 12.1% FOC, 72.9 ft-lbs KE, 20-50 drop of 28.5", KE @ 50: 62 ft-lbs.  125 grain head would be fine: recommended spine of .310" and would be 6.15 gr/lb.

Diamond @ 65#: 275 fps, 6.24 gr/lb, 68.4 ft-lbs KE, 20-50 drop 30.8", KE @ 50 58.2 ft-lbs, recommended spine of .337".  I like this better than buying new broadheads!

PSE @ 60: 230 fps, 406 gr arrow, 9.25% FOC, 6.8 gr/lb, 47.8 ft-lbs KE, 20-50 drop of 48.7", KE @ 50: 37.9 ft-lbs, rec. spine of .440" (those are .400" spine arrows), so not bad at all.

PSE @ 55: 221 fps, 7.4 gr/lb, 44.1 ft-lbs KE, 53.2" drop, 35 ft-lbs @ 50, rec. spine of .473".

[mallard79]

Thanks Todd.  You are the man!

I am new to bow hunting, but when I calculated my arrow weight I came up with 423.35 grains.  Am I wrong in adding the weight of the nock, insert, and vanes to the total arrow weight?  I used 9.3gpi, 5 grains per vane, 21 grains for the insert and 13 grains for the nock(taken from the Cabelas description on their customer review page).  I want to make sure I am doing my math correctly in the future.

If you wouldn't mind, could you tell me what dropping to an 85 grain broadhead with the PSE would do to it's numbers?

Thanks again!

[Todd_ID]

Going lighter on broadheads for the PSE makes for a 7.7% FOC, and that's almost impossible to get to fly well.  I'd stick with the 100's.

The program shows the Stalker Extremes at 8.7 gpi, so there's the difference.  Your numbers are right as they are 9.3 gpi, so you'll be a little slower (maybe 5 fps), a little less FOC (very little), grains per inch legal.

[mallard79]

Going lighter on broadheads for the PSE makes for a 7.7% FOC, and that's almost impossible to get to fly well.  I'd stick with the 100's.

The program shows the Stalker Extremes at 8.7 gpi, so there's the difference.  Your numbers are right as they are 9.3 gpi, so you'll be a little slower (maybe 5 fps), a little less FOC (very little), grains per inch legal.

That is what I was thinking, but wanted to make sure.  I will stick with the 100's in the PSE.  I am going to try both 100 and 125's from the Diamond this week and go with whatever fly's best.

Thanks for all the help!

[et1702]

Hi Todd,

I have a 2007 Hoyt Trycon XL, 76lbs, 31-inch draw, 75/95 Gold Tip XT Hunters, Magnus Buzzcut 4-blades 125gr, 29-inch shaft length, HP vanes (three per shaft), string loop w/Cater release.

[Todd_ID]

Hi Todd,

I have a 2007 Hoyt Trycon XL, 76lbs, 31-inch draw, 75/95 Gold Tip XT Hunters, Magnus Buzzcut 4-blades 125gr, 29-inch shaft length, HP vanes (three per shaft), string loop w/Cater release.

It shows 308fps, 426 gr arrow, 5.9 gr/in (oops), 13.7% FOC, 89.9 ft-lbs KE, 20-50 drop of 23.4", KE @ 50: 76.4 ft-lbs, recommended spine of .295", so your .340" Gold Tips are pretty weak.  Drop it to 65#, and it's still weak with a recommended spine of .315", but not quite so bad.  Plus, you'd be legal with 6.5 gr/lb and still getting 295 fps and 82.7 ft-lbs KE. Better all the way around: 

[et1702]

Yikes, I just switched to the 8.9gr/in shafts and didn't do the math.  At 426gr total weight, I get 5.6gr, not 5.9.  legal is 6.0gr/lb...right? 

Do Carbon Express Maxima Hunters change the equation much?  I think they are the same gr/in of shaft.  But, are they a stiffer spine?  I'd rather not go below 70lbs if I can help it (i.e., 426gr/70lb = 6.08gr/lb).

Thanks,

ET

[Todd_ID]

Yikes, I just switched to the 8.9gr/in shafts and didn't do the math.  At 426gr total weight, I get 5.6gr, not 5.9.  legal is 6.0gr/lb...right? 

Do Carbon Express Maxima Hunters change the equation much?  I think they are the same gr/in of shaft.  But, are they a stiffer spine?  I'd rather not go below 70lbs if I can help it (i.e., 426gr/70lb = 6.08gr/lb).

Thanks,

ET

Shows the CE Maxima Hunter 450's at .298" spine, so that'd be pretty much perfect to leave your setup the way it is.  That's a 450 grain arrow with your 125's.  The gr/lb on your current setup is 426/72=5.9.  Maybe my grains are off on the program, but probably not more than a couple.  My opinion is it's not worth the $120 for another dozen arrows when all you need to do is turn the bow down some, but that's just me.  Most guys are pulling about 10# too much weight, so it's generally a safe recommendation.  If you can sit in a chair, lift your legs off the floor, and draw the bow straight out in front of you with no more movement than you want to have with a whitetail looking at you, then your draw weight is ok.  Most can't pass this test....  Your bow has a ton of energy stored in it that you can afford to draw lesser draw weights and still blow through a cape buffalo.

[et1702]

Thanks Todd,

There aren't many arrows out there with a spine at around .300 or stiffer.  I found some Beeman ICS hunters at 9.5gpi with .300 spine.  Otherwise its the Maxima 450's, CE Pile drivers (too heavy), or Gold Tip Big Game Hunters.  FYI, I know what you mean about too much draw weight.  My buddy sat on his stand for two to 3 hours in below freezing temps and when a 150 class whitetail stepped out in front of him he couldn't pull his bow back to save his life!  My bow is 70 to 80lb range.  Most compounds are more efficient closer to the top of their range, and I don't have any problems pulling back after sitting three hours in below freezing temps.  So, I'd rather use the right spine arrows for the job (and ones that are legal).  Regarding KE of this bow, I love it!  The last few elk, deer, and bears have all been complete pass thru's!  In fact, none of them went more than 30 yards.  The last elk I shot took four or five steps, stood there a moment and then fell over in his tracks.  I think KE is more important than speed.  Just like torque is really what gets your truck, or race car moving!  However, since it's one week from opening morning for ELK, I may just turn her down to 70lbs so I'm legal.  BTW, although spine is marginal.  I tune my bow thru paper every year, and these shafts w/ broadheads are hitting the same point of impact as my field points.

[carpsniperg2]

try shooting 83-84 lbs i might just have to start chunkin rebar and fletching them to make weight

et1702 you might look at the easton fmj's they should get you to the weight of arrow you need and you can keep that ke up and the arch down

[et1702]

Hey CarpSniper,

I did shoot 84lbs...with only 35% let-off.  Remember the Golden Eagle bows???  I shot that thing from 1986 thru 2006.  Now I'm dating myself.  But, I did start bow hunting at 15 years old with an old Darton over 31 years ago.  BTW, if I crank my Hoyt all the way down, she will go over 80#.  But, I already start my sight pins at 30yrds (i.e., no 20yrd pin), and can shoot very tight groups all the way out to 60yrds.  But, everything I've shot over the years has been 30yrds or less.

Also, thanks for the suggestion. I'll look at the FMJ's