FMJ Spine Confusion

[eh254413]

I’m running into some confusion with Easton’s FMJ spine chart.

My setup is a Hoyt Helix Turbo at 67# and 29.5 draw

I bought 300 spine arrows with a 4 fletch and with standard inserts and a 100 grain head it comes to 504gr.

I would like to run a weighted insert but am concerned it will leave me under spined.

What do you guys think?

 

[LONE HUNTER]

With a carbon to carbon length of 28.5 inches, a 75 grain HIT and a 100 grain broadhead you would be about perfect. Ran those numbers through archers advantage and its on the lower side of optimal spine but still in the green. If your arrows are much longer than that you would be more on the marginally weak side with a brass insert.

 

[Dylan Sluis]

I would think that you would be fine. I am 29" pulling 72lbs with a 300 spine 175 grains up front and they work good for me. So you should be pretty good.

 

[Zac]

I think you should consider other shafts. Nothing but sorrow is waiting for you with the FMJ.

 

[Mighty Mouse]

Assuming a 29.25" 5mm FMJ 300 (12 gpi) with 100 gr head, 16 gr HIT, four 7 gr vanes, and 9 gr nock (for a 504 gr TAW), qSpine says your spine is spot on. You could easily add another 50-75 gr to the front and still be fine with a 300. You should have room to trim at least an inch off the arrow if you did want to stiffen it a bit.

 

[Red Letters]

If you don’t mind me asking, I bought some arrows told my local bow shop I wanted to add weight with a heavier inserts and they installed the standard weight ones. I tried ordering a screw in insert to add more weight but bought the wrong item. It sounds like that is what you were doing what did you plan on using?

sorry not trying to highjack, I’ll edit this out if needed

 

[bigW]

Assuming a 29.25" 5mm FMJ 300 (12 gpi) with 100 gr head, 16 gr HIT, four 7 gr vanes, and 9 gr nock (for a 504 gr TAW), qSpine says your spine is spot on. You could easily add another 50-75 gr to the front and still be fine with a 300. You should have room to trim at least an inch off the arrow if you did want to stiffen it a bit.
View attachment 373874

...one of the best APPs when it comes to arrow building

 

[eh254413]

If you don’t mind me asking, I bought some arrows told my local bow shop I wanted to add weight with a heavier inserts and they installed the standard weight ones. I tried ordering a screw in insert to add more weight but bought the wrong item. It sounds like that is what you were doing what did you plan on using?

sorry not trying to highjack, I’ll edit this out if needed

I actually used BlackOvis arrow builder to make the arrow I wanted, but asked them not to glue in the inserts. I will put weighted inserts in myself but I wanted to check on here where people with more experience than myself could chime in. Sorry I couldn’t be of more help.

 

[Mighty Mouse]

If you don’t mind me asking, I bought some arrows told my local bow shop I wanted to add weight with a heavier inserts and they installed the standard weight ones. I tried ordering a screw in insert to add more weight but bought the wrong item. It sounds like that is what you were doing what did you plan on using?

sorry not trying to highjack, I’ll edit this out if needed

What diameter are your arrows and what insert do they have in them? Not all inserts have rear-facing threads for screw in weights. HIT inserts, which are commonly used in micro (.166"/4mm) and small (.204"/5mm) arrows, don't have rear-facing threads.

 

[Red Letters]

What diameter are your arrows and what insert do they have in them? Not all inserts have rear-facing threads for screw in weights. HIT inserts, which are commonly used in micro (.166"/4mm) and small (.204"/5mm) arrows, don't have rear-facing threads.

Axis 5mm, I’m not sure what actual insert they use. I ask about the weight prior to the screw up and I’m pretty sure he said the standard ones were 35 grain. When I ask about removing them he said it was next to impossible to get them out?

 

[LONE HUNTER]

Axis 5mm, I’m not sure what actual insert they use. I ask about the weight prior to the screw up and I’m pretty sure he said the standard ones were 35 grain. When I ask about removing them he said it was next to impossible to get them out?

The standard HIT for the 5mm axis is 16 grains, the aluminum one. The Brass insert is 75 grains and you can bust off a portion of it to make it 50 grains.

 

[Mighty Mouse]

Axis 5mm, I’m not sure what actual insert they use. I ask about the weight prior to the screw up and I’m pretty sure he said the standard ones were 35 grain. When I ask about removing them he said it was next to impossible to get them out?

Easton makes 5mm hidden inserts (HIT's) in 16, 50, and 75 gr. They also offer 5mm half-outs in 25 gr (aluminum) and 75 gr (steel).

If they're epoxied in (which they probably are) you're unlikely to get them out. You could try the "drill bit method" (take out the nock, slide a drill bit inside the arrow, hold the arrow by the nock end and point it upward, swing the arrow downward as hard as you can so the drill bit slides forward and slams into the rear of the insert), but you may ruin the arrow.