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Old 01-29-2016, 02:45 PM   #1
Closetohome
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Default FOC vs Momentum vs Trajectory - Which to choose?

Here is an interesting scenario I have been wrestling with.

I currently own and shoot Easton Axis 260s with 75gr brass inserts and 100gr heads cut @29.5 Finished arrow weight is 540gr. and I have chronographed them at 278fps. They work out to a 14.46% FOC with 0.6651 momentum via OT2. Nothing to sneeze at.

I have been tinkering with other arrows and started looking at the Black Eagle Spartans in 250 spine. I'm guessing I can get an arrow to finish in the 515-520gr range with the 75gr brass screw in weights cut at 29" and push them a little quicker based on OT2 at around 283fps. Works out to a higher 17.65% FOC but lower momentum of 0.6510.

Other alternative is only using one 30gr. brass screw in insert weight on the Spartans @29" with a finished arrow weight around 473gr which keeps my FOC around my Easton's at 14.64% but flattens the trajectory out a bit at 296fps.

The bow will be used mainly for hunting out West for animals ranging in size from deer to elk and ranges from 0-70yds. Bow specs are 70lb Mathews Halon 5 @70/29" w/75% LO. All weights are assuming 100gr tips.
So which would you choose? Mass with highest momentum? Highest FOC with lower momentum? Sacrifice FOC and momentum for trajectory?
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Old 01-29-2016, 02:52 PM   #2
SwampRabbit
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Assuming that all three combinations are flying well tuned, I'd go with the 540gr arrow personally.
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Old 01-29-2016, 04:37 PM   #3
Mudslinger
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Heavier arrows will maintain their speed better down range better than lighter arrows. Just saying. Personally the 540 grain would be my choice.
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Old 01-29-2016, 04:56 PM   #4
enewman
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Between the two. If your momentum numbers are correct there alittle over 2% difference.
Not enough to matter.

The 17.65% foc arrow should out penetrate the 14.46% foc arrow. Now this is the testing Dr Ashbey has done. Again it's not going to be much more. You don't see a real improvement till 19% foc.

Either arrow will work. If your speed numbers are good then there is not that big of deference either. So go with the 540 gn.

Personally. If I could get 278 fps with a 540 gn arrow. I would be shooting a 600 gn arrow.
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Old 01-29-2016, 05:42 PM   #5
rocky
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You would have to shoot a whole bunch of big animals, with all three options, before you could determine the difference.
473 grains @ 296 fps is lots of killing power and flat trajectory that will aid you on the longer shots that you might have to take.
In hunting situations, it's not always possible to range the animal.
That's why the masses like the speed.
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Old 01-29-2016, 06:39 PM   #6
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FOC
Momentum is an added bonus.

I read somewhere about building YOUR perfect arrow.
It went something like
build the heaviest arrow with the most FOC that has an acceptable trajectory. THAT is YOUR perfect arrow
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Old 01-29-2016, 06:48 PM   #7
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I have on more than one occasion swayed a client or two towards a heavier/high-E FOC set up in lieu of a lighter arrow. Simply put you loss killing efficiency more than anything else. Trajectory can totally be compensated for.....Sight in your bow, know your distances it's as simple at that. If you can misjudge by a full pin in excess 30 yds you have no business shooting that far IMO. The difference in the poi from 305 to 280 launch at 40 yds is virtually non-existent so why sacrifice lethality for no real value added performance. Sight in, know your distance and do work. Build an arrow for less than ideal situations.
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Old 01-29-2016, 06:48 PM   #8
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You can have your cake and eat it too btw.
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Old 01-29-2016, 06:59 PM   #9
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Quote:
Originally Posted by muddyfuzzy View Post
You can have your cake and eat it too btw.
I like chocolate
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Old 01-29-2016, 07:05 PM   #10
Texans42
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Quote:
Originally Posted by Closetohome View Post
Here is an interesting scenario I have been wrestling with.

I currently own and shoot Easton Axis 260s with 75gr brass inserts and 100gr heads cut @29.5 Finished arrow weight is 540gr. and I have chronographed them at 278fps. They work out to a 14.46% FOC with 0.6651 momentum via OT2. Nothing to sneeze at.

I have been tinkering with other arrows and started looking at the Black Eagle Spartans in 250 spine. I'm guessing I can get an arrow to finish in the 515-520gr range with the 75gr brass screw in weights cut at 29" and push them a little quicker based on OT2 at around 283fps. Works out to a higher 17.65% FOC but lower momentum of 0.6510.

Other alternative is only using one 30gr. brass screw in insert weight on the Spartans @29" with a finished arrow weight around 473gr which keeps my FOC around my Easton's at 14.64% but flattens the trajectory out a bit at 296fps.

The bow will be used mainly for hunting out West for animals ranging in size from deer to elk and ranges from 0-70yds. Bow specs are 70lb Mathews Halon 5 @70/29" w/75% LO. All weights are assuming 100gr tips.
So which would you choose? Mass with highest momentum? Highest FOC with lower momentum? Sacrifice FOC and momentum for trajectory?
all three of those options are well and above what it takes to penetrate and pass tru a western game animal. And that includes to 70 yards.

Don't over think it. Relax, settle and exhale and release.
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Old 01-29-2016, 09:18 PM   #11
Closetohome
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Quote:
Originally Posted by rocky View Post
You would have to shoot a whole bunch of big animals, with all three options, before you could determine the difference.
473 grains @ 296 fps is lots of killing power and flat trajectory that will aid you on the longer shots that you might have to take.
In hunting situations, it's not always possible to range the animal.
That's why the masses like the speed.
This is what intrigues me about this combo. I had a big bull come into a bugle one year and the situation still haunts me. We bugled and weren't setup correctly and the bull came rushing in and stopped broadside at and undetermined yardage. I drew back and asked my buddy to range him but neither of us could move. I had him guessed at 50 yards and my buddy guessed 60. Before we could move he blew out of there. This was all in a matter of 10 seconds. We later ranged the spot at 53yds and in hindsight I should have shot. A flatter trajectory would have benefitted and narrower pin gap would have given me more confidence to take that shot.

The other part of me says stick with the 540s as a less than perfect shot would have benefitted from the mass.

It is a bit of over analysis but I want one arrow for the life of the bow. I want to get the flattest trajectory for deer sized animals but have the mass and FOC for a tensed up slightly quartering bugling bull.
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Old 01-29-2016, 09:22 PM   #12
Closetohome
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Quote:
Originally Posted by muddyfuzzy View Post
I have on more than one occasion swayed a client or two towards a heavier/high-E FOC set up in lieu of a lighter arrow. Simply put you loss killing efficiency more than anything else. Trajectory can totally be compensated for.....Sight in your bow, know your distances it's as simple at that. If you can misjudge by a full pin in excess 30 yds you have no business shooting that far IMO. The difference in the poi from 305 to 280 launch at 40 yds is virtually non-existent so why sacrifice lethality for no real value added performance. Sight in, know your distance and do work. Build an arrow for less than ideal situations.
Good advice. Going to spend some more range time this weekend with the Easton 260s and see how I like them.
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Old 01-30-2016, 06:23 PM   #13
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Originally Posted by muddyfuzzy View Post
You can have your cake and eat it too btw.

Could you make mine either German Chocolate or Devil's Food?
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Old 01-30-2016, 06:40 PM   #14
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MuddyFuzzy just made me some Black Eagle Spartans, 545 gr total weight 17.6% FOC. I have not chrono'd my setup yet but my point of impact is unchanged out to 40 yards. I have 0 intentions of attempting a white tail any further than that. Hog maybe. Bow is noticeably quieter and as I said my poi is unchanged. I don't see a down side to them. Can't wait to sink one in an animal.
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Old 01-30-2016, 06:42 PM   #15
Closetohome
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Quote:
Originally Posted by gmac View Post
MuddyFuzzy just made me some Black Eagle Spartans, 545 gr total weight 17.6% FOC. I have not chrono'd my setup yet but my point of impact is unchanged out to 40 yards. I have 0 intentions of attempting a white tail any further than that. Hog maybe. Bow is noticeably quieter and as I said my poi is unchanged. I don't see a down side to them. Can't wait to sink one in an animal.
What length are your Spartans?
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Old 01-30-2016, 06:50 PM   #16
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28"
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Old 01-31-2016, 09:19 AM   #17
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Either, all you need is to work on the loose nut behind the string to insure accuracy.
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Old 01-31-2016, 11:18 AM   #18
Texans42
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Quote:
Originally Posted by Closetohome View Post
This is what intrigues me about this combo. I had a big bull come into a bugle one year and the situation still haunts me. We bugled and weren't setup correctly and the bull came rushing in and stopped broadside at and undetermined yardage. I drew back and asked my buddy to range him but neither of us could move. I had him guessed at 50 yards and my buddy guessed 60. Before we could move he blew out of there. This was all in a matter of 10 seconds. We later ranged the spot at 53yds and in hindsight I should have shot. A flatter trajectory would have benefitted and narrower pin gap would have given me more confidence to take that shot.

The other part of me says stick with the 540s as a less than perfect shot would have benefitted from the mass.

It is a bit of over analysis but I want one arrow for the life of the bow. I want to get the flattest trajectory for deer sized animals but have the mass and FOC for a tensed up slightly quartering bugling bull.
415gr .57momentum 17foc
Passtru 60 yard mulie(quartering away)
Passtru 75 yard mulie
Passtru 50 yard elk (severe quartering away)
Passtru 60 yard pronghorn

Ulmer edge broad head and solids

Don't over think it.
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