That's a very difficult question to answer in the manner it's been asked. Before I could even attempt to answer your question you'd need to be much more specific in clarifying it.
At what distance are we talking about?
What type of groupings are you experiencing with your four vane arrows?
What type of a performance improvement are you looking for or compared to what?
I'll state the improvements and benefits that typically were supposed to come from this modification.
Prior to the modification of the upper rail, your crossbow would have likely caused one or more of your arrow vanes to come in contact with the underside of your upper weaver rail once every some many shots. This would have caused a flier condition where you would periodically have noticed one arrow a few inches outside the spot you were shooting at. You would have no explanation for this event because you would have felt certain your crosshairs were on center when you pulled the trigger. This flier condition is a direct result of your arrows vanes not having good clearance and the launch causes the back end of the arrow to make contact with your Weaver Rail. This results in a disrupted launch process causing less than desired results on the face of your target.
Although you can shot 3 vane fletching configurations (and I do), in order to obtain better performance than with my 4 vane arrows, I need to re-tune my crossbow to shoot the three vane configuration arrows. They will not shoot or perform the same as a four vane, therefore my point of impact changes so my windage adjustment must be changed accordingly.
Three vane will fly at a slightly higher velocity because they have less "Drag" affecting the tail of the arrow and they weigh slightly less. This can account for as much as 5 or 6 fps. greater speed.
For the record, I have 2 dozen PSE TAC15 Arrows that are Spine Matched, Nock Indexed, and Weight Balanced that are perfectly tuned to my crossbow. I will not change these and these are what I shoot for hunting and a good deal of the time.
I also have 1 dozen PSE TAC15 Arrows that were build exactly the same way except they were done in three vane configurations. These also shoot perfectly once I re-tune my crossbow for them. At up to 100 yards, if any arrow is not within 1" or 2" of my aim point, then I know the problem was either a slight breeze or me, but never the crossbow or arrows.
Last, I also have a dozen of the "Firenock" Aerobolt II arrows, that were done in a 3 vane configuration. After receiving them, I Spine Tested each and indexed the nocks to the stiff side of the spine on each arrow. I then aligned my vanes with the stiff side of the spine and weight balanced each arrow to within 2/100ths. of a grain i weight of one another.
I can't tell you how well these arrows group, because I won't shoot more than one arrow at any given dot at any distance. These are my tack drivers and are reserved only for my most serious shooting. Once tuned to the crossbow these arrows are capable of same hole accuracy at almost any distance.
I haven't been able to shoot more than 1 arrow at my targets at any distance under 60 yards for over a year now, so grouping is something I only attempt at distances over 80 yards.
My suggestion, is that you work with a given vane configuration until you have it tuned to your crossbow. There are many factors which can alter flight performance, so there's a number of tuning changes that can be made to attain better flight performance. Temperature variations will always affect elevation and velocity especially at longer distances. Weight deviations will affect grouping performance at distances 60 yards or over. Unless your arrow nocks have been indexed to your arrows spine, you arrows oscillations are occurring in all different directions. This is a Dynamic Spine Deflection Timing Difference.
In simple terms it means your arrows are not flexing in the same directions and therefore it equates to arrow performance differences. It's the same difference as with a gun shooting precision matched ammo versus store bought off the shelf ammo. The only difference is with a crossbow and arrows the differences are greatly magnified.
Once you have settings that support the type of performance your looking for, unless you're into just experimenting, don't fix what isn't broke.
Hope this helps you understand why your question is not easy to answer as asked.
Hi, Jon. Great info for us TAC shooters. I have a couple questions if you don't mind. How does one Spine Match the Tac 15 arrows and how would I weight balance them? the Nock indexing is pretty straight forward. I have an issue with my arrows. They vary in length and weight. There is a 3-4 mm difference in length and as much as 12-13 gns in weight. This is through out the 18 arrows that I purchased.
You mention "Firenock" Aerobolt II arrows. is this an arrow that is now available to use in the TAC? I know we are only supposed to use the proper TAC 15 arrows, but it would be nice to have options like we do with other crossbows and compound bows.
Any help and advice would be very much appreciated.
Let's start with the easiest stuff first. The "Firenock" products are also known as Aerobolt II's and are produced by Firenock.com. They are a super high quality arrow that is made specifically to replace the factory PSE TAC15 arrows.
The only down side is that they are expensive, but you do get what you pay for. Every aspect of the Aerobolt II's are made with precision. Their Inserts and their points are machined to very exacting tolerances that nobody else in the industry even comes close to. The shafts are a specially produced version of an Easton Carbon Shaft that is a multi-spined shaft. You must let "Dorge" know that the arrows need to be fletched for the TAC15 crossbow. This way he will produce them in a 4 fletch, 60 x 120 fletching pattern.
To your question about Spine Matching? It requires the use of a Carbon Spine Tester in order to test and match your arrow spines. As each arrow is tested on the spine meter you will record the high and lower range readings on a piece of paper. If they were PSE TAC shafts for example, you might have readings such as .0159 - .0170 for one shaft. Then .0160 - .0168 for another and .0163 - .0170 for a third. All of these shafts are closely related enough to be in the same spine grouping. As long as the deviation in spine readings are within a few points of one another they will perform similarly. If they are more than a few points off from the main readings, they need to placed into a separate spine grouping.
The particular spine tester that use is by RAM Products and it's the RAM QC Carbon Spine Tester. Their number is 208-882-1396. On the RAM Spine Tester the highest number reading on the gauge indicates the stiff side of the arrow spine. It is this "Stiff Side" marking that is marked first in the center of the arrow spine and then transferred to the nock end of the shaft in order to orient the nocks to the stiff side of the spine.
RAM supplies some very good instructions with their product on the step by steps for each of these activities and they also have very good product support for their customers in the event one has any questions.
When I have PSE Arrows that are different lengths, this is not very critical because there's an over abundance of extra length of arrow shaft that hangs over the front of the crossbow at full draw, so it's far more important to get all shafts weighing the same, than it is to be of exactly the same length.
I use an electric Horizon Arrow Cut-off Saw to cut and adjust my arrow shafts.
Start by weighing all bare shaft before any work is performed and before any vanes have been placed on them. In this case one must identify their lightest weight arrow shaft because it's far easier to take weight off all others than it would be to add weight to the lightest shafts. I start by shaving 1/16 or thinner slices off my heavier shafts and then weighing each until I get it close to the weight of my lightest shafts. When finished with this process your shafts should be fairly close in weight. They do not need to be anywhere near exact because vanes and nocks being added will change their weight before you are done.
Next, I complete all spine testing and also mark the stiff side of each arrow shaft.
Then I insert my new nocks. For this step I only use Firenock "D" nocks and insert them without any glue, so they can easily be removed when I'm ready. I'm only putting the nocks 3/4's of the way in and aligning them with the stiff side marking on the shaft such that the stiff side marking is in the 12:00 o'clock position when the arrow is on the string of the crossbow.
Once this alignment has been performed, you can now perform your vane fletching. As each arrow is completed, just set it aside and allow it to dry overnight.
Once all vanes have been completed the nocks can be removed and set aside. Each arrow now needs to be weighed and the weight needs to be written down next to what number arrow it is in the group you are producing. When finished you should have a list numbered 1 - 12 or how ever many you are making and next to each the weight of each shaft measured in tens or 100ths of a grain. one decimal place to the right of the decimal point is tens. two positions after it would be the 100ths column.
You will then begin with the heaviest shaft and add a bull dog nock collar (Carbon Express Bull Dog Nock Collar CXL250) is the correct size for PSE TAC15 Arrow Shafts). These are held on by using a very small amount of slow setting Epoxy Cement and then add one of the nocks you set aside from that earlier step. Use a very small amount of glue to the nock also and make sure you align the nock back in the correct position so the stiff side of the arrow shaft is in the 12:00 o'clock position when the arrow is on the string.
Once this has been done, you need to immediately weigh this arrow and record the weight on paper next to this arrow number. This weight is important because all other arrows will be brought to this weight by adding as much glue as necessary to achieve this exact weight. Therefore you must work with your arrow scale next to you at all times. If the weight comes out higher than this weight you will pull out the nock with a set o pliers and remove some glue. If the arrow weighs less than the weight of the first arrow, the you will use pliers and remove the nock to add another drop of glue. You can place glue on the inside hollow part of the nock if necessary to add more. Once you are within one or two tenths of a grain seat the nock permanently by pushing it all he way in as far as it will go. Remember to always double check the nocks alignment to the stiff side of the spine marking on your arrow shaft to insure each one is aligned with the stiff side at 12:00 o'clock when finished.
Repeat these steps until all arrows are fully finished and then allow 24 hours to completely dry.
When finished, you will have created a completely matched, tuned and weight balanced set off arrows that will perform as well and better than anything you can buy anywhere.
I can achieve consistent perfect arrow performance from my 4 fletch arrows and although I can also achieve this with a set of Dorges, Aerobolt II's, I can't get any better grouping from one over the other because the oscillation and timing on both are as good as it can be. If one is willing to put in this much work they can achieve outstanding performance from either arrow, so it's hard to advocate a 3 vane configuration over a 4 vane configuration.
Even Dorge's arrows are not nock aligned to the stiff side of is arrows spines, so if you want the best possible performance from his arrows, this step needs to be performed in order to achieve it.
There are no known manufacturers who routinely perform this function, so it's a custom tuning step that the shooter must perform if desired.
Hi Jon, that is a lot of very useful information. I was very careful to do most of that with the bolts for my other crossbows. But I was unsure of the spine matching technique. I guess I got lucky with that. I was able to build dozens of 20" bolts that shot very well for me. Robin hooding was an issue at ranges under 4o yards. Grouping was always three in a 2" area. But now, I want to do this at 80-90 even 100 yards. with your info and advise I think this will be done. The TAC 15i is not for everyone that's for sure. But I think I will make believers out of a few skeptics this fall. Thanks again for the info Jon.
No worries whoopass800. As you increase the distance of your shots these factors become much more critical to maintain tight grouping performance.
If you ever watch the u-tube video's on people shooting the TAC15's at long distances and making very accurate shots at distances from 50 yards - 100 yards you'll come to understand this was only possible by using the same arrow for each shot. When changing arrows, it requires a level of tuning that is only obtainable by following the steps that I've provided.
This is an easy way to determine if somebody is using some trick camera activity to fake the shots or if in fact they can actually make the shots. Unless they've taken the time to perfectly match their arrows in advance, the shots aren't possible when multiple arrows are involved.
How did you think crossbow competitive shooters are achieving the scoring results they achieve? Only through the use of these matching and tuning steps.