Insert questions.

[andydwyer]

Hey fellas,

I'm pretty new to archery, and I'm running into some confusion. I'm trying to add weight to my arrow setup, but I can't figure out what I'm supposed to buy.

I'm using CX 300s which I gather have been out of production for a while -- I'm pretty sure they're .244 diameter and 30" long. My buddy "lent" me his old setup; everything is very lightly used but 15 years old.

Anyways, I'm looking to add a 100gr insert and then test with a variety of point weights to get the best flight. Theres a lot of info out there, and I'm getting lost in the weeds. Especially since none of the archery pro shops around me carry this kind of stuff.

Any recommendations on what insert to get? And why you'd choose that one?

 

[Mighty Mouse]

Any run-of-the-mill aluminum insert will work fine for testing purposes as long as the insert OD matches the arrow ID. Measure the arrow ID with calipers if you have a set. I ordered these off-brand .244" aluminum inserts from Amazon this spring to build some target/3D arrows and was very pleased with the quality/consistency, especially at such a low price: https://www.amazon.com/dp/B07PR8BQLM/ref=cm_sw_r_cp_apa_i_HFBgFbC1AP588

The quickest/easiest way to experiment with arrow weight would be to shoot field points of various weights. 100 and 125 grain points are pretty common. 150, 175, 200 gr can be found but are less common. Field points are typically sold in quantities of 12, but if you don't want to commit to that many, GrizzlyStik offers a test kit consisting of 6 different points ranging from 100 to 315 gr: https://www.grizzlystik.com/mobile/GrizzlyStik-Field-Point-Testbr-6-Pack-1-Each-P164.aspx

A slightly more advanced method of weight testing would be to add weight inside the arrow behind the insert. With inserts that are fully threaded all the way through (which most are), you can thread weight screws into the rear of the insert. Gold Tip's FACT weights are designed for this purpose, but you could make your own weight screws by taking 8-32 machine screws and grinding down the heads. GT FACT weights have the benefits of being able to stack individual weights on top of each other and being able to add/remove the weights without removing the insert itself by using GT's extra long hex wrench.

Regardless of the insert or weighting method you choose, I'd recommend using heat reversible glue (aka, "hot melt" such as Bohning Cool Flex) to secure your inserts so you can remove them easily if you decide to change your setup. Inserts secured with epoxy are much more difficult (sometimes impossible) to remove without damaging the arrow shaft. Once you've settled on an insert configuration, you can always switch from hot melt to epoxy if you're worried about hot melt not holding well enough. I have had a few hot melted inserts pull out in very tight targets over the years, but it's a rare occurrence (and epoxy isn't completely foolproof).

 

[MattB]

You can't just add an additional 100 gr. out front without first validating you will maintain proper dynamic spine.

 

[Mighty Mouse]

You can't just add an additional 100 gr. out front without first validating you will maintain proper dynamic spine.

Great point. 100 gr is a significant amount of weight and could easily push the OP's arrow from overspined/properly spined to underspined. Probably not dangerously underspined, but it could be enough to cause tuning issues and poor broadhead flight.

@aaaandy, what's your current total arrow weight, draw weight, and draw length?

 

[andydwyer]

Right now, I'm pulling 62lbs at 28.5" with a 385gr arrow. I'm pretty sure that a CX 300 is 300 spine

Thanks for the replies, guys.

 

[Mighty Mouse]

Right now, I'm pulling 62lbs at 28.5" with a 385gr arrow. I'm pretty sure that a CX 300 is 300 spine

You should be fine adding 100 gr at those specs. At your draw length, you have room to cut your arrows down from 30" and make them stiffer if you wanted to. Below is a Gold Tip spine chart that can be used as a reference point, but like most charts, it tops out at 150 gr point weight and (presumably) assumes a standard weight (≈12 gr) aluminum insert. GT's chart implies that for every 50 gr of additional point weight you need to reduce spine deflection (increase stiffness) about 0.050", but I get increasingly skeptical of spine charts as weight increases and I don't think that implied 0.050" per 50 gr relationship holds true when you get into the 500+ gr realm of total arrow weights. Victory has a pretty good spine calculator on their website that allows you to enter individual component weights.


One thing to be aware of is that Carbon Express's numbering system is effectively opposite of all other manufacturers: higher model numbers for stiffer (lower spine deflection) arrows and lower model numbers for weaker (higher spine deflection) arrows. For all brands I'm aware of except for CX, an arrow's model number is equal to its static spine deflection measured in inches times 1,000. For example, a Gold Tip Hunter 340 has a static spine deflection value of 0.340". CX's model numbers don't directly correlate to actual spine deflection, so don't assume that your CX 300 arrow has a 0.300" spine; you'll have to look up the actual spine for your specific arrow model.

 

[andydwyer]

From what I can tell, the CX 300 is .340 spine... So I'd be under spined with with 150g up front. Sounds like I need some stiffer arrows if I want 500-550gr with high FoC.

Shoot, I thought that model number corresponded with the spine.

 

[nettereo16]

The CX arrow names are wack! My first set of carbon arrows 15 years ago were CX somethings 250s. They were like .400 spine. Clear as mud...

 

[Jimbob]

Ya Carbon express was like "let's do things backwards, it will make it so easy for everyone". My CX maxima 450 were around .300 I think.

Are your arrows already cut with inserts installed?

Try some 125-grain tips and see how it shoots, which will put you at 410 which is decent. When its time for new arrows then look at a heavier weight.