GT Kinetic Pierce Platinum?

[Lytro]

I'm already looking at what I want to build for arrows after this season and I've been thinking about giving these a try. I'm currently shooting match grade FMJ 300's @ 579 gr total arrow weight, drawing 70#/30". (50 gr brass HITs, 100 gr points, vinyl wrap, and AAE Max Stealth 4 fletch). Shooting 264 fps out of my Triax. They shoot pretty well and hit like a freight train, but I'd like to increase FOC and flatten out my trajectory a little.

Looking at the GT Kinetic Pierce Platinum 250's (standard insert, ballistic collar, 125 gr point, 4 fletch AAE Max Stealth), I believe I would be right around 510 gr total arrow weight. This setup would increase FOC about 4%, put me up around 290 fps, and give me an extra 5# KE.

Does anyone have any input on the GT Kinetic Pierce Platinums? Pros & Cons?

 

[big44a4]

Bigger fan of BE X-impact or rampage. They have been more consistently straight in my experience.


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[Lytro]

Bigger fan of BE X-impact or rampage. They have been more consistently straight in my experience.


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I didn't consider BE, but they fit the bill and a little more cost effective. What components have you combined with the X-Impacts? I haven't used any type of outsert in the past.

 

[Dos Perros]

I don't like BE's insert design. I lost a bull after an arrow blew up on some ribs. The insert blew out the side of the carbon, the elk kept my insert and broadhead and the all of the splintered carbon was there on the ground. I much prefer their outsert where the end of the carbon is constrained on the outside. I am currently running their Deep Impacts. I like the design of the Pierce Platinums/Ballistic Collar Insert System and I wouldn't hesitate to give them a shot. I think rolling straight carbon arrows has become almost a commodity business.

 

[big44a4]

I didn't consider BE, but they fit the bill and a little more cost effective. What components have you combined with the X-Impacts? I haven't used any type of outsert in the past.

Their FOCOS outsert sleeve/system for the X-impacts is solid. Also the stainless half out for the rampages has done well on rock impact from with a 493 gr arrow at 290 FPS.


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[Lytro]

Their FOCOS outsert sleeve/system for the X-impacts is solid. Also the stainless half out for the rampages has done well on rock impact from with a 493 gr arrow at 290 FPS.


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I was just playing around with the numbers and I could build some with their standard outserts with a 125 point = 490 gr/293 fps/12.2% foc/93.4 ft-lbs KE.

It’s sounding pretty good!

 

[MattB]

KE shouldn't increase when going to a lighter arrow, not sure about the calcs.

I personally wouldn't chase FOC and would do a bit of work to better understand the trajectory difference between the 2 arrows at 264 fps and 290 fps. The juice may not be worth the squeeze unless you are on of those folks who just likes to tinker and play with new gear. My observation based on looking at guys who frequently change gear is that it doesn't generally improve their success, and perhaps more to the opposite. There is some benefit to familiarity.

 

[Lytro]

KE shouldn't increase when going to a lighter arrow, not sure about the calcs.

I personally wouldn't chase FOC and would do a bit of work to better understand the trajectory difference between the 2 arrows at 264 fps and 290 fps. The juice may not be worth the squeeze unless you are on of those folks who just likes to tinker and play with new gear. My observation based on looking at guys who frequently change gear is that it doesn't generally improve their success, and perhaps more to the opposite. There is some benefit to familiarity.

KE certainly increases if you're gaining speed without dropping too much weight. KE isn't entirely based on the weight of the arrow. The calculations don't lie.

As far as changing my setup, I think it's definitely worth it if I can increase performance. My current arrows hit like a freight train, but there are areas for improvement. Mainly, I'm slightly underspined with the FMJ and I can't go any stiffer. Thus, I need to look at other options.

 

[MattB]

KE certainly increases if you're gaining speed without dropping too much weight. KE isn't entirely based on the weight of the arrow. The calculations don't lie.

As far as changing my setup, I think it's definitely worth it if I can increase performance. My current arrows hit like a freight train, but there are areas for improvement. Mainly, I'm slightly underspined with the FMJ and I can't go any stiffer. Thus, I need to look at other options.

Nope. The bow is only capable of generating so much energy, and in every case I've chrono'd KE increased with arrow weight as a heavier arrow is able to absorb more of the bow's energy. It's just physics. The difference is beyond marginal.

Arrow weight however has some demonstrated advantages.

And I guaranty you that if you did in fact happen upon the very rare case of a bow that is highly inefficient with heavier arrows, the difference is not 5 lb./ft. when you are talking a weight difference of less than 100 grs.

I am not throwing this out to be argumentative or to prove anything, I just hate to see people spend a bunch of money only to be disappointed because they based expectations on flawed assumptions. Like I said above, if you just want to tinker have at it, but don't expect to get what you think you will because you won't.

 

[Zac]

The FMJ is a much straighter arrow. I've used both, I would not let the shop touch the Pierce's. You need to pre spin all of them and cut off both sides accordingly. Also getting them extremely square is important. You'll probably want to hot melt components and spin and reheat the collars until you get them perfect, they are very finicky. That being said they have the potential to be a great shaft, I love all the tinkering, the FMJs practically build themselves. Both great arrows though.

 

[Lytro]

Nope. The bow is only capable of generating so much energy, and in every case I've chrono'd KE increased with arrow weight as a heavier arrow is able to absorb more of the bow's energy. It's just physics. The difference is beyond marginal.

Arrow weight however has some demonstrated advantages.

And I guaranty you that if you did in fact happen upon the very rare case of a bow that is highly inefficient with heavier arrows, the difference is not 5 lb./ft. when you are talking a weight difference of less than 100 grs.

I am not throwing this out to be argumentative or to prove anything, I just hate to see people spend a bunch of money only to be disappointed because they based expectations on flawed assumptions. Like I said above, if you just want to tinker have at it, but don't expect to get what you think you will because you won't.

I’m not sure how you can say “it’s just physics” but completely ignore physics. KE is calculated from a mathematical equation, and not just shooting through a chrono. In this case it increased by less weight/more speed. It sounds like you don’t understand how KE is generated, but that’s besides the point. KE wasn’t the deciding factor on changing arrows (89 ft-lbs is more than enough)

Like I said in my previous post, I’m slightly underspined with the FMJ 300 at that weight/length and I can’t fix that. I could either live with that (why would I?), or I could try something new in the off-season. Regardless, I will be building a dozen arrows and it’s only a $9 difference in cost between the two brands. I’m confident that accuracy will remain the same at minimum, so there should be no reason to be disappointed. All I’m looking for in this thread is to hear what others have to say about the GT Pierce or other comparable arrows from experience.

 

[MattB]

I’m not sure how you can say “it’s just physics” but completely ignore physics. KE is calculated from a mathematical equation, and not just shooting through a chrono. In this case it increased by less weight/more speed. It sounds like you don’t understand how KE is generated, but that’s besides the point. KE wasn’t the deciding factor on changing arrows (89 ft-lbs is more than enough)

Like I said in my previous post, I’m slightly underspined with the FMJ 300 at that weight/length and I can’t fix that. I could either live with that (why would I?), or I could try something new in the off-season. Regardless, I will be building a dozen arrows and it’s only a $9 difference in cost between the two brands. I’m confident that accuracy will remain the same at minimum, so there should be no reason to be disappointed. All I’m looking for in this thread is to hear what others have to say about the GT Pierce or other comparable arrows from experience.

I've been playing with bows, chronos, and KE equations for 20+ years. My guess is you've read about it on the internet and used a calculator or two, and probably haven't gotten much further than noting the velocity is squared in the formula and have taken that to mean something it doesn't. I say this specifically in regards to your comment above about KE increasing if you don't drop too much arrow weight. This is indicative of you having a fundamental misunderstanding of the relationship between the inputs into the math equation you referenced. Where do you think you get the inputs for that equation if not a grain scale and a chronograph?

Every bow I have tested with arrows from 400 to 635 grain arrows has shown a marginal increase (less than 1 lb/ft over the range) in KE with the heavier arrows. The physics is that heavier arrows absorb more of the bow's energy. That is also why heavier arrows tend to quiet a bow. Simple. It's physics.

 

[Dos Perros]

The bow can only store so much energy. That energy is dictated by you, the energy you put into it. If you were to plot a draw curve and integrate the curve to sum the area under the curve you come up with the stored amount of energy. Then if you were to chrono an arrow point blank out of the bow you could calculate it's KE. It will be less than the energy put into the bow because there are always inefficiencies, but not much. Bows these days are somewhere around 97% efficient last I checked (and if I remember correctly). Varying arrow weights, even wildly, will not impact the amount of point blank KE. A super heavy arrow might retain 98% of the stored energy, and a light one 97%.

As MattB said the difference is marginal.

 

[Lytro]

Why does every reference for arrow KE produce the same calculations, and have a wide variance depending on arrow weight and speed variables? Everything is contrary to what you're stating. Am I calculating and referring to something entirely different?

Side note: This thread has gotten way off topic. Lol

 

[Dos Perros]

Do me a favor?

Input into your calculator of choice:

one bow input, same bow same DL same draw weight
two different arrow imputs, everything the same but arrow #1 350gr total arrow weight and arrow #2 550gr total arrow weight. You could just alter broadhead weight 50gr to 250gr I bet. Post the velocities of both arrows. If the calculator includes it post the KE of both arrows. Then we can compare.

 

[Yooper]

I've shot the GT Pierce Platinum arrows the last two seasons. I've got nothing but good things to say about them. I build my own so I cut both ends and square accordingly. I'll need to order new arrows again soon and when I do it'll be GT PP's again. For what it's worth I've shot Axis, FMJ, BE Rampage, and a few others.

 

[Lytro]

Do me a favor?

Input into your calculator of choice:

one bow input, same bow same DL same draw weight
two different arrow imputs, everything the same but arrow #1 350gr total arrow weight and arrow #2 550gr total arrow weight. You could just alter broadhead weight 50gr to 250gr I bet. Post the velocities of both arrows. If the calculator includes it post the KE of both arrows. Then we can compare.

I had these ones saved from when I was making calculations for the difference between my current arrow and a hypothetical BE build. I’ve shot my current through a chrono, and it matches the calculation in the attached screenshot.

 

[MattB]

Why does every reference for arrow KE produce the same calculations, and have a wide variance depending on arrow weight and speed variables? Everything is contrary to what you're stating. Am I calculating and referring to something entirely different?

Side note: This thread has gotten way off topic. Lol

There is only one KE calculation. When you compare different bow and arrow combinations, there can be significant differences in KE.

But when you are comparing different arrow weights out of the same bow, there will be very little difference across a wide variety of arrow weights. That bow only stores so much energy and the only difference from arrow to arrow is the very small efficiency loss referenced above. Heavier arrows are generally more efficient, although some bows so perform better with lighter arrows. Again, marginal differences.

My best guess as to why the difference is bad inputs or built-in assumptions in a calculator in terms of how many fps are gained from a given decrease in arrow weight, etc. I have seen a fair bit of variance from actual, measured results compared to calculated estimates.

 

[Lytro]

I've shot the GT Pierce Platinum arrows the last two seasons. I've got nothing but good things to say about them. I build my own so I cut both ends and square accordingly. I'll need to order new arrows again soon and when I do it'll be GT PP's again. For what it's worth I've shot Axis, FMJ, BE Rampage, and a few others.

Thanks for your input, Yooper. It sounds like the GT PP are a little finicky to set up, but everyone seems to love them from a performance standpoint.

 

[Nick Muche]

I've shot the Pierce Platinum (and Tours) in 250 spine for the past few years (recurve and compound) with absolutely no issues, from deer to bison. I don't tinker much, just build my arrows to fly straight out of my bow and these do just that.