Vane size in relation to point weight

[45-90scout]

I'm shooting a Nitrum 34 @ 50lbs with 30" 5mm FMJ arrows. When I bought the vanes, they came with the standard 2" Blazer vanes, which is great with 100 gr. points. I've moved up in weight to points weighing 150 grains plus whatever the insert weighs.

My question is this. With the added weight on the front should I increase the vane length to maybe 3"? I rarely shoot past 50 meters.

[Pasc43]

Tough to say. I would try out both and see what groups best. With that long of arrow 3" might be better but it's also going to slow it down more. I'd be more concerned about spine after upping your point weight that much.

[45-90scout]

Was using the 400 spine with 100 grains. Checked the Easton spine chart and with my setup and new point weight - had to go to 340.

[Coiloil37]

Vane size and point weight don’t correlate that way but they are related.

Your vanes control the front of the arrow. The arrow is a given length and there is a “center” point on that arrow. To calculate the Front Of Center you have to find the balance point on said shaft.
By increasing your point weight you’ve moved the FOC forward thereby giving the fletching a longer fulcrum to control the front of the shaft.
The size of the broad head, bow tune, form or perhaps if the point wasn’t straight in line with the shaft would necessitate larger fletching (or just find and fix the problem). Having to low FOC may result in hard to tune or unpredictable arrow flight but what you’ve done isn’t going to be an issue in regard to the way you’ve asked the question. If anything it will increase stability with the same fletching IF you haven’t created any other problems.

[jcrayford]

Vane size and point weight don’t correlate that way but they are related.

Your vanes control the front of the arrow. The arrow is a given length and there is a “center” point on that arrow. To calculate the Front Of Center you have to find the balance point on said shaft.
By increasing your point weight you’ve moved the FOC forward thereby giving the fletching a longer fulcrum to control the front of the shaft.
The size of the broad head, bow tune, form or perhaps if the point wasn’t straight in line with the shaft would necessitate larger fletching (or just find and fix the problem). Having to low FOC may result in hard to tune or unpredictable arrow flight but what you’ve done isn’t going to be an issue in regard to the way you’ve asked the question. If anything it will increase stability with the same fletching IF you haven’t created any other problems.

Now, where is that slow clap button?

Coil's speaking the truth there.

My only comment to 45-90 would be, what's a 5mm FMJ? I shoot FMJ's and have seen the entire line up. They are all 5mm in diameter, just different weight / spine classes.

J.

[45-90scout]

There are 4mm, 5mm and 6mm FMJ.
Looks like a tapered was just released.


https://eastonarchery.com/huntingarrows/