Archers Advantage - How accurate on FPS and thus Spine Selection?

[philcox]

So I am using AA to setup my Sight Tape and my uphill/downhill sheet. Seems that the sight tape and uphill/downhill measurements are spot on. My question is that it says my Nexus 2 28.5 DL, 70# is shooting my 575 gr Hunter XT 300 spine arrow at 238 FPS. That seems a bit slow, but like I said, the tape and cut chart seem to be spot on. While I really don't care about the FPS reading, it does say that I should be shooting a 340 spine arrow, where all the gold tip charts say 300 spine. So a couple questions:

1. Are the AA spine recommendations right on? E.g., should I throw a 340 spine arrow, or keep with the 300?

2. Is the FPS in AA more realistic? My Caldwell has it at 250ish

Any insight, especially on the spine info, is appreciated.

Phil

 

[Billy Goat]

I find the spine to be a middle road. What I have found to tune well for target is on the weak side, while what I find for hunting is always on the stiff side.


The speeds have always lined up with my chrono for what it's worth. But it is dependent on your inputs. So if you are off somewhere a little, it will definitely show up on the fps. Things can also effect the fps like your helical and vane height, that will all cause an arrow to slow down faster at distance, I usually don't use too much helical and tallest vane is .450.

Edit-
FOC is always off too. Lower than what I find when I actually test, frequently by 1.5-2%. I don't worry about it much, just try to keep hunting arrows over 10 and target 7+.

 

[Meshnasty]

General advice - Use the shaft selector to get close when looking at new arrows, but then enter in the proposed length, etc. in the set up tab with all the details for the most accurate estimate of spine/fps. I've gotten different results when I do this. Always double check that your set up is correctly inputted as well. I think my chrono was 2-3 fps slower then what AA was saying. I actually just went to double check what AA had for FPS and my bow was changed to a Mathews when it's actually an Elite. I haven't used AA in 5-6 months, but always verify your set up.

My tapes have been pretty good, normally I use one that is 1-2 FPS slower then the actually chrono and it helps from 80-110yds on my slider. I've had a couple tapes where I had to add a yard in the 80's, 2 yards in the 90's, 3 yards in the 100's. I have a decent amount of helical on my arrows though.

 

[Planopurist]

Sounds like if your tape is accurate, so is the speed calculation. A very good competitive archer friend told me that he has bettter success with arrow tunes that are “slightly stiff” by AA calculations.


@StraightWayOutdoors
Straight Way Outdoors, Fulcrum Archery, Elite Archery, Upwind Odor Elimination, Wicked Twisted Bowstrings, Pine Ridge Archery, Sevr Broadheads, Bloodline Fibers, Element Arrows

 

[Billy Goat]

Sounds like if your tape is accurate, so is the speed calculation. A very good competitive archer friend told me that he has bettter success with arrow tunes that are “slightly stiff” by AA calculations.


@StraightWayOutdoors
Straight Way Outdoors, Fulcrum Archery, Elite Archery, Upwind Odor Elimination, Wicked Twisted Bowstrings, Pine Ridge Archery, Sevr Broadheads, Bloodline Fibers, Element Arrows

That indoor or outdoor?

Indoor is usually always stiff. I don't know anyone who uses a stiff arrow outdoors, not that I know everyone.

 

[philcox]

I have meticulously calculated all of the inputs to AA, I guess I just need to buy some 340's and test them out. Thx.

 

[CodeMonkey]

For the spine calc, make sure you have the "jaws" release selected, otherwise it will report stiffer than reality.

I have found the sight tape it craps out stupid accurate, provided the measurements for peep height, etc. were done properly.

 

[philcox]

For the spine calc, make sure you have the "jaws" release selected, otherwise it will report stiffer than reality.

I have found the sight tape it craps out stupid accurate, provided the measurements for peep height, etc. were done properly.

Selecting Jaws puts me at Optimal with the 300 (which makes sense), I did not find anything about the type of release. Why would it not be "tied loop" (I assumed that was a D-Loop).

 

[Billy Goat]

Selecting Jaws puts me at Optimal with the 300 (which makes sense), I did not find anything about the type of release. Why would it not be "tied loop" (I assumed that was a D-Loop).

You want tied loop selected.


Make sure that on the spine selection screen your fps is close to correct. It doesn't always transfer. Personally I'd stay with the 300's for hunting, assuming they are flying good for you. To get a 300 pro hunter to 575gr you must have a good bit of weight on the front.

 

[Mighty Mouse]

340 definitely seems weak for the amount of weight you must have on the front (I'm guessing 250+ gr).

 

[CodeMonkey]

You want tied loop selected.

Not saying which piece of software is correct, but with "tied loop" selected, my arrow build is stiff per archer's advantage.

"Jaws" matches the outputs I get out of Pinwheel and what various spine charts seem to be hinting at.

 

[philcox]

You want tied loop selected.


Make sure that on the spine selection screen your fps is close to correct. It doesn't always transfer. Personally I'd stay with the 300's for hunting, assuming they are flying good for you. To get a 300 pro hunter to 575gr you must have a good bit of weight on the front.

Got it on the tied loop. FPS is correct, based on the calcs that AA does.

Yes, I am running a 125g BH, 100g brass insert, 50g FACT weight, so basically 275g up front. Arrow is 28.625", std GT nock and 3 Blazers. 300's are flying good, and BH group with my FP's. I don't get super tight groups, but can pretty consistently get MOA groups. I bought some 340's to try out, and if they don't do any better, I'll stick with my 300's.

 

[Billy Goat]

Got it on the tied loop. FPS is correct, based on the calcs that AA does.

Yes, I am running a 125g BH, 100g brass insert, 50g FACT weight, so basically 275g up front. Arrow is 28.625", std GT nock and 3 Blazers. 300's are flying good, and BH group with my FP's. I don't get super tight groups, but can pretty consistently get MOA groups. I bought some 340's to try out, and if they don't do any better, I'll stick with my 300's.

Something seems off. I wouldn't be trying to get broadheads to fly on the front of a 28.5" 340 with 275 gr on the front, pushed by 70#, but that's me, and I'm not too familiar with your bow so maybe it really likes weak.

Like I said, I have found for me what I actually want is a hunting arrow on the stiff side, and a target arrow on the weak side. Not too weak, too stiff, but it's normally out of the optimum window and slightly or marginal in the direction.
Figured that out after a while, had to keep cutting hunting arrows shorter to get them to really tune.

 

[Billy Goat]

How did you calculate your speed in AA? Did you use dials on your sight or measure with calipers?

At your specs, if it's shooting 232fps, or 248fps it's a big difference in spine.

I haven't ever entered things numerically on the program, it's always been by reading the dials. But if you were off a little, it will really change your fps. My quick numbers say you should be 245-250 fps, but I'm not familiar with those bows to really know if they hit their speeds.

 

[Planopurist]

That indoor or outdoor?

Indoor is usually always stiff. I don't know anyone who uses a stiff arrow outdoors, not that I know everyone.

He shoots mostly field, but a little bit of everything competitively. He’s multiple state championships and more podium finishes. He hunts as well. I’ve personally had success with everything from slightly weak to slightly stiff, from .204 ID to .246 ID to 26s.


Sent from my iPhone using Tapatalk

 

[Mighty Mouse]

Yes, I am running a 125g BH, 100g brass insert, 50g FACT weight, so basically 275g up front. Arrow is 28.625", std GT nock and 3 Blazers. 300's are flying good, and BH group with my FP's. I don't get super tight groups, but can pretty consistently get MOA groups. I bought some 340's to try out, and if they don't do any better, I'll stick with my 300's.

FWIW below is the output from Pinwheel for your current setup.
Bow inputs: 341 fps IBO, 70# DW, 28.5" DL, 32" ATA, 6" BH, 80% LO
Arrow inuputs: 28.625" C2C, 275 gr on front, 12 gr nock, 3 vanes at 6.5 gr/ea

 

[philcox]

Something seems off. I wouldn't be trying to get broadheads to fly on the front of a 28.5" 340 with 275 gr on the front, pushed by 70#, but that's me, and I'm not too familiar with your bow so maybe it really likes weak.

Like I said, I have found for me what I actually want is a hunting arrow on the stiff side, and a target arrow on the weak side. Not too weak, too stiff, but it's normally out of the optimum window and slightly or marginal in the direction.
Figured that out after a while, had to keep cutting hunting arrows shorter to get them to really tune.

Got it. I definitely keep that in consideration. Thanks for the notes. I am shooting a Prime Nexus 2.

 

[philcox]

How did you calculate your speed in AA? Did you use dials on your sight or measure with calipers?

At your specs, if it's shooting 232fps, or 248fps it's a big difference in spine.

I haven't ever entered things numerically on the program, it's always been by reading the dials. But if you were off a little, it will really change your fps. My quick numbers say you should be 245-250 fps, but I'm not familiar with those bows to really know if they hit their speeds.

I did the inch measurement. Shot at 30 yds (used 0) and 80 yds (1.198"). Comes out at 238.2 fps. Used calipers to measure everything. I followed the steps outlined by the guy in this video

 

[philcox]

FWIW below is the output from Pinwheel for your current setup.
Bow inputs: 341 fps IBO, 70# DW, 28.5" DL, 32" ATA, 6" BH, 80% LO
Arrow inuputs: 28.625" C2C, 275 gr on front, 12 gr nock, 3 vanes at 6.5 gr/ea
View attachment 393559

The 262.55 FPS is over 24 fps more than my measurements give me from AA (238.2). I am guessing that is the difference in the AA "stiff" and Pinwheel "weak"

 

[Kyle Wheeler]

My speeds were a little slower than chrono but tapes are dead on. I used the sight in method and my chrono was 286 but with sight in method said I was actually 283.8 and that tape works perfect.