FMJ arrow configuration to augment FOC

Junibravo

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I am shooting FMJ 340 spine 27.5inch shaft with a lighted nock, 125 grain and 50 grain hit insert with my 65# bow at 29in draw length. My current FOC is 13%. I am hoping to augment my FOC some, get it around 15-18%, by using 75 grain inserts instead. Any thoughts on whether i need a tougher spine arrow to add the extra 25 grain to the insert or should the 340 work ok?
 
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It's going to depend on what bow it's coming out of. I know it wouldn't work for me at 65# and 28.5 draw.

If FOC is what you want, then you would be best to start with a lighter arrow.

According to Easton (who has spent more money than anyone else I'd bet researching it) you are already in the ideal range for a hunting arrow. I'm pretty certain all of the FMJ shafts use hit inserts, so they should be epoxied in, makes it difficult to just change the inserts. Point being I think it's going to be a little difficult to do without building new arrows all together.

Can get 150 grain field points and just use a 25 grain collar with you current broadheads. Less expense to try it out.

Edit: Some FMJ's, the 6mm and t64 use the rps insert.
 
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Not Vegan

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Maybe you can lighten up the back with lighter vanes. Also you could add a footer.
 
OP
J

Junibravo

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I am planning to use iron will 25g collars to allow me us to use 100grain field points with the same weight up front (allows me more variety of broadheads to choose from). I can always use 125g broadheads on top of the 25g collars.
my concern was that i did not want to experiment adding weight up front and reach a weight where the spine is weakened to the point that the arrow breaks or something
 
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The arrow isn't going to break from being a weak spine.


It's not going to broadhead tune, but you would need to be way, way, underspined to be worried about breaking an arrow.
 

Bmoore

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Whats the upside of carbon arrows?
Lighter gpi which makes gaining FOC much easier because the same spine arrow will be lighter all around allowing you to put the weight up front.
People tend to dislike FMJ because they can bend and render the arrow useless. Full carbon either shatters or doesn’t. And they tend not to shatter all that easily so your left with a more durable arrow. I’ve avoided FMJs for the two reasons I just listed. But everyone like different things so it’s really up to you with what you like.
 

5MilesBack

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Whats the upside of carbon arrows?
I thought I was really going to like the FMJ's, and I did for a couple weeks. They were accurate, consistent, and pulled easily from targets. But after a couple weeks, they were less consistent and accurate, and just got worse from there. I put them on a spinner and the front 6-8" wobbled like crazy. My club had heavy rubber matting on the backside of the bales, and that was about all I could come up with to cause that. And I was just getting started with those FMJ's, I hadn't even shot them through 3/4" plywood or 2x6's yet like I do with all my carbons. So the upside to "good" carbon arrows is durability.
 

MattB

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Whats the upside of carbon arrows?
They don't bend.

But more importantly they would open the up the option for you to implement more mental masturbatory changes and spend more money that won't translate to a more effective arrow anywhere other than on the internet.

In all seriousness, FOC is way overrated, 13% is fine, and FMJ's are the wrong arrows to use if you want to play the FOC game because of the high GPI. Good luck.
 

sf jakey

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FMJ’s may bend after lots of practice shots, but they don’t break on impact with bone, and they are heavy, so they make a great hunting arrow. Get a dozen, tune them for hunting with your broadheads, and put them away. They fly great, hit hard, and penetrate.
FOC is just fine where you are, don’t waste your time trying for more.
 
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I had FMJ'S bend in two weeks of shooting foam.

I'm not sold that they won't break any easier than carbon. They are really thin aluminum coupled with thin carbon.


However I have had good luck with ACC's, so go figure.
 

5MilesBack

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However I have had good luck with ACC's, so go figure.
I loved my ACC's, but they weren't very durable beyond target shooting. I hit rebar going up the leg of a 3D target with an FMJ and that arrow was all kinds of messed up with aluminum curled back and crooked as heck. I've hit rebar in 3D targets with my carbons and it's always just mushroomed the FP tip.
 
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I shoot 5mm FMJ and I asked my bow shop guy about adding weight to it and he said it would be difficult because the shaft itself is so heavy. Like others have said, it would be easier to start with a new arrow build. Its unfortunate to have to abandon those arrows but if you want high FOC its probably a better use of your time and money to just do a proper high foc build.
 

bcv

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Feathers for vanes.
If it were me with your goal I would have started with at least 300 spine sticks. The way I build em now is go for the lowest spine they sell. I'm shooting 250 spines out of my 70/29. I don't care what anyone on the internet posts... A hunting compound bow can not be over spined. I've spent years experimenting with that and know for certain this to be true out of 60-70 pound bows and 27-30 inch draw.
 
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I am shooting FMJ 340 spine 27.5inch shaft with a lighted nock, 125 grain and 50 grain hit insert with my 65# bow at 29in draw length. My current FOC is 13%. I am hoping to augment my FOC some, get it around 15-18%, by using 75 grain inserts instead. Any thoughts on whether i need a tougher spine arrow to add the extra 25 grain to the insert or should the 340 work ok?
you need an axis ;)

i know many have good luck with fmj's, but i personally wouldn't shoot them if they were free.
 

Trial153

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I really like carbon and aluminum shafts, I just don’t like FMJ…I think their durability sucks.

ACC on the other hand are money. Run them with Brass H inserts to get all the weight you want up front
 
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