Limb failures

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xpert1111
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Limb failures

Post by xpert1111 »

Can anyone, especially an Excalibur representative tell me exactly what weight I should be using with the Assasin 420TD? Minimum weight is 350 grains and I understand that is bare minimum to attain the approximate 420 fps advertised speed. Is there a downside to minimum weight like limb splintering? Shooting around 410 grains and now I will be on my 4th set of limbs. I am reading a lot here but mostly on the Excalibur FB page and hearing other's problem with various Ecxalibur bows and their limb failures. Many are saying you need to be shooting heavier bolts like in the 600-700 grains. I am a speed guy and the reason for buying the 420TD. I know they say speed does't kill. To me it does. I hunt fields and have taken many deer at 60+ yards with my Matrix 380 and 420TD. Like having the power to reach deer at these longer distances. This is also another reason I prefer the crossbow over a compound. I have blasted through front shoulder and out the rear ham, complete passthrough with mechanicals at 45 yards this year and another through both shoulders at 50. I am not having a problem with KE or FOC it would appear. If my shots are all under 30 yds I would not care about speed but like I said I shoot longer distances. Are we talking a huge speed loss at 600-700 grains? I was thinking I would be shooting around 320-340 fps at this weight? I know still fast but not for me. Just disappointed on my 4th set of limbs with this fairly new bow!
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Re: Limb failures

Post by vixenmaster »

I would set up arrows around 400 - 425 gr n let'em rip. Thats what i shoot using my BD360, so mine is a lot slower than yours
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Boo
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Re: Limb failures

Post by Boo »

I am not a representative. But if it were me, I'd go to 450 grains. To me, that is right in between too light and too heavy. That means you'll utilize the power to gain momentum and have a decent trajectory. 425 would be ok too but there isn't a whole lot of difference. What would be sensible is to use Black Eagle Arrows and use their additional weights that screw onto the backside of the front insert and play with weights until it feels right for you as far as how it feels, sound and the trajectory. You will find that as you add weight to the front, your accuracy improves, the shot is quieter and feels better.
I am using 400 grains in my 400 Suppressor. It almost feels abusive but I know the limbs on the 400 will just shrug it off. Everyting just feels right at that speed. But keep in mind that there is no big difference in anything with a 25 grain jump in weight.
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xpert1111
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Re: Limb failures

Post by xpert1111 »

Boo wrote:
Fri Nov 12, 2021 11:11 am
I am not a representative. But if it were me, I'd go to 450 grains. To me, that is right in between too light and too heavy. That means you'll utilize the power to gain momentum and have a decent trajectory. 425 would be ok too but there isn't a whole lot of difference. What would be sensible is to use Black Eagle Arrows and use their additional weights that screw onto the backside of the front insert and play with weights until it feels right for you as far as how it feels, sound and the trajectory. You will find that as you add weight to the front, your accuracy improves, the shot is quieter and feels better.
I am using 400 grains in my 400 Suppressor. It almost feels abusive but I know the limbs on the 400 will just shrug it off. Everyting just feels right at that speed. But keep in mind that there is no big difference in anything with a 25 grain jump in weight.
Thanks Boo. I am shooting 18" BE Executioners with 92 grain brass inserts. Doesn't make sense to up to the 110 grains but was reading someone got heavier washers from someone who builds arrows. So you think the extra 40 grains would help with these limb issues? That is my main concern. Noise is never an issue as no deer have been ducking this bow at longer yards. But afraid if I slow down too much they will.
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Re: Limb failures

Post by Boo »

I might be wrong but you may be able to use 20". I used 21" in my 440. As far as washers go, you may not get much thread engagement with 40 grains of washers under your broadhead. The insert weights make more sense in that respect and are available in 30, 50 and 75 grains https://blackeaglearrows.com/exec-zomb-brass-insert-weights/. I've used 15 and 10 grain from Ethics Archery and 15 is the limit for enough thread engagement for me. I'm a mechanic by trade so stuff like thread engagement is important to me.
Leftover energy and how much your limbs flex is what contributes most to limb failure. Any added weight takes energy from the limbs so yes, it will help. How much I don't know.
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xpert1111
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Re: Limb failures

Post by xpert1111 »

Boo wrote:
Fri Nov 12, 2021 12:44 pm
I might be wrong but you may be able to use 20". I used 21" in my 440. As far as washers go, you may not get much thread engagement with 40 grains of washers under your broadhead. The insert weights make more sense in that respect and are available in 30, 50 and 75 grains https://blackeaglearrows.com/exec-zomb-brass-insert-weights/. I've used 15 and 10 grain from Ethics Archery and 15 is the limit for enough thread engagement for me. I'm a mechanic by trade so stuff like thread engagement is important to me.
Leftover energy and how much your limbs flex is what contributes most to limb failure. Any added weight takes energy from the limbs so yes, it will help. How much I don't know.
Thanks Boo I will look into the BE insert weights!
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nchunterkw
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Re: Limb failures

Post by nchunterkw »

Insert weights, heavier broadheads, heavy string....doesn't matter where the weight comes from.
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Re: Limb failures

Post by xcaliber »

nchunterkw wrote:
Tue Nov 16, 2021 9:28 am
Insert weights, heavier broadheads, heavy string....doesn't matter where the weight comes from.
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Re: Limb failures

Post by Prmtvbowman22 »

Three rivers archery sells 25 50 and75gr. points that are tapped to screw in your broadhead. Looks like a blunt field point. Adds about a half inch to bolt length but an easy fix.
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Re: Limb failures

Post by DMc »

xpert1111 wrote:
Fri Nov 12, 2021 7:56 am
... Minimum weight is 350 grains and I understand that is bare minimum to attain the approximate 420 fps advertised speed... Shooting around 410 grains and now I will be on my 4th set of limbs...
The op has stated that he likes speed and that the advertised speed was a determining factor in his purchase.

If a bow cannot do what is claimed without fear of failure, might it not be wiser and more honest to adjust that claim?
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Re: Limb failures

Post by Boo »

Speeds with a given arrow weight is a way of telling a potential buyer what to expect power wise. There are other companies that use 350 as a baseline. Mission is the first one that comes to mind. From that information one can extrapolate what you can get with higher weights. Some companies use 385, some use 390 and some 400. Who are we to tell manufacturers what arrow weight to use for their baseline numbers?
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DMc
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Re: Limb failures

Post by DMc »

Boo wrote:
Fri Nov 19, 2021 12:25 pm
... Who are we to tell manufacturers what arrow weight to use for their baseline numbers?
Inconsistent rating systems are often used by sellers to keep consumers from making direct comparisons. Be that as it may, whatever numbers are given, they should at least work without fears of failure from using them, no?
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xpert1111
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Re: Limb failures

Post by xpert1111 »

Let's not even use the minimum weight Exaclibur states. People are having problems using much heavier bolts. There should be a recall on these bows period!
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Re: Limb failures

Post by nchunterkw »

xpert1111 wrote:
Fri Nov 12, 2021 7:56 am
Are we talking a huge speed loss at 600-700 grains? I was thinking I would be shooting around 320-340 fps at this weight? I know still fast but not for me.
Speed loss with these limbs is in the 1 fps/3gr or 1fps/4gr ballpark

At 1fps per 4gr.
600gr-350gr = 250gr/4 = 62.5fps. SO 420-62.5 = 357.5fps.
700gr = 332.5fps
500gr = 382.5 fps

At 1 fps per 3gr.
600gr-350gr = 250gr/3 = 83.3fps. So 420-83.3 = 336.7fps.
700gr = 303.33fps
500gr = 370fps


Maybe a good compromise for you is a 500gr arrow flying around 375fps? Really fast and will blow through an elk, bison or moose let alone a deer.

Another thing you may consider is to make heavy arrows that do not have a really high FOC. Having a more balanced arrow (like by using a shaft within a shaft instead of just heavy inserts and BHs) will result in a much flatter trajectory even at lower speeds at the ranges you are talking about. And FWIW, (you would know better than me as you shoot deer way out there), I don't think their reaction to the shot is as violent when they are 50 yards away, versus 25 or 30. So from a "jumping the string" perspective, maybe the speed loss wouldn't be a factor if the trajectory is flatter.
Keith
Stand by the roads and look, and ask for the ancient paths; where the good way is,
and walk in it and find rest for your souls. - Jer 6:16

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xpert1111
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Re: Limb failures

Post by xpert1111 »

nchunterkw wrote:
Fri Nov 19, 2021 12:49 pm
xpert1111 wrote:
Fri Nov 12, 2021 7:56 am
Are we talking a huge speed loss at 600-700 grains? I was thinking I would be shooting around 320-340 fps at this weight? I know still fast but not for me.
Speed loss with these limbs is in the 1 fps/3gr or 1fps/4gr ballpark

At 1fps per 4gr.
600gr-350gr = 250gr/4 = 62.5fps. SO 420-62.5 = 357.5fps.
700gr = 332.5fps
500gr = 382.5 fps

At 1 fps per 3gr.
600gr-350gr = 250gr/3 = 83.3fps. So 420-83.3 = 336.7fps.
700gr = 303.33fps
500gr = 370fps


Maybe a good compromise for you is a 500gr arrow flying around 375fps? Really fast and will blow through an elk, bison or moose let alone a deer.

Another thing you may consider is to make heavy arrows that do not have a really high FOC. Having a more balanced arrow (like by using a shaft within a shaft instead of just heavy inserts and BHs) will result in a much flatter trajectory even at lower speeds at the ranges you are talking about. And FWIW, (you would know better than me as you shoot deer way out there), I don't think their reaction to the shot is as violent when they are 50 yards away, versus 25 or 30. So from a "jumping the string" perspective, maybe the speed loss wouldn't be a factor if the trajectory is flatter.
I'd take 375 in a heartbeat but many are saying 500 grain still too light and will damage limbs
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