I currently shoot fmj 340's. I'm wanting to get a little heavier and increase my foc by adding a 75 grain brass insert, but stick with the fmj's. I could step up in spine and go with the 300's, but they are only .7 gpi heavier. So I was thinking of getting the dangerous game fmj 300's, which are 16gpi and that should put me around 630 grains or if I stick with the regular fmj 300's I would be around 530 grains. Question is, does anybody use or have experience with the dangerous game shafts and do you think the extra 100 grains is worth it? I'll be shooting this set up out of a hoyt crx35 65lbs 28.5"draw. Currently with the 340's I'm about 425 grains without the brass insert. Also was wondering if I add the 75 grain brass insert to the 340's I currently shoot, if you think the spine will be to weak? I'm thinking it might make them a tad weak but idk for sure. Shafts cut at 27"to the throat. Thanks
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I would think the 340 with the 75 insert is going to put you on the weak side. Cannot check on program right now. Now power.
Your not going to get a lot of foc with arrows with this much gpi. So since you like the fmj. I would not worry to much about that -
Well right now with my current set up, I'm right at 11%. So I was thinking with the 75 grain insert in the regular fmj 300's, with them not being much heavier (.7gpi) , that it would get me closer to 14-15% foc. I'm kinda new to the foc game, but I like a little heavier arrowand I love fmj shafts lolComment
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You will prolly just go to the 12/13% rangeComment
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It might get you there. Muddy might chime in. I'm sure he has a rough idea how much gain in foc per gn you add up,front.Comment
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Idk how accurate it is, but I just ran some numbers through the gold tip foc calculator. If I could get away with adding the insert to the 340's I will be at 14.07% and 13.56% with the 300's. So if that is accurate, that's pretty close to what I'm wanting to achieve.Comment
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Fmj's
On an average GPI shaft (8-9 GPI) increasing tip weight (or decreasing tail weight) around 25 grains will net you about a 1% gain in FOC. The other factor is arrow length as the shorter the arrow (all else being equal) will always produce more FOC. The FMJ is a great shaft but for a high or extreme FOC build it can present difficulties getting there since it has an exceptional weight per inch compared to other shafts.
Case in point:
Just finished these today for a customer, they weigh 492 with 16.25% FOC. I ran an additional 20 grains on these to get to the respectable 16.25% on these 250's that weigh 9.7 GPI. The same arrow in a 300 at 8.5 GPI running 20 grains less up front is around 455 with and easy 18%.Comment
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Thanks for the input muddy. That helped, but I like fmj's cz I don't have to worry about them breaking on me. I've had a carbon shaft snap on release before, how it didn't go in my arm/hand is beyond me. With the fmj's I don't have to worry as much. But if 25 grains adds 1% like you said and I'm already at 11%, then the insert will get me where I'm wanting to be, in that 14-15%.Comment
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no it won't, the 1% is based off a 8-9 GPI shaft. the FMJ is a lot more than that which makes building FOC more challenging. With the GPI shaft you are looking at you are probably looking at more like .25-.50% per 25 grains of tip weight.Originally posted by TxHunter06 View PostComment
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the 340's using the 75 grain insert and 100 grain tip cut to 27" AMO puts you at about .320 spine as ideal, so you are weak. The FOC is decent on the set-up at 15.5% but its far from optimal. a better alternative would be to drop down to the 300, increase the length to 27.5" and change over to a 125 grain tip. this would give you a FOC north of 16% and set the spine to nearly perfect.Originally posted by TxHunter06 View PostComment
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I agree with the a ove you need to go to a full carbon arrow to raise your GPI very much. I would switch back to axis and check your arrows for cracking often.
What kind of carbon did you have break?Comment
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That sounds good and that goes inline with my thinking of the 340's being to weak. Are these numbers using fmj's?Originally posted by muddyfuzzy View PostComment
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