Wasting my time - trying to get my arrows to weigh the same.

Discussion in 'General Crossbow Discussion' started by bltefft, Jan 7, 2016.

  1. bltefft

    bltefft Active Member

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    Wasting my time - trying to get my arrows to weigh the same.

    A little while ago I made the attempt to get all my arrows REAL close in weight by adding insert weighs, some I even ground down to make the weight adjustment.

    For example, I have 10 arrows, the lightest weighs 422.5 grains and the heaviest, 426.6 grains. I would have tried to bring all their weights up to 426.6 grains - and I did, give or take 0.1 grain. And then I read this:

    "Usually if the arrow is 7 or 8 grains difference you will probably not notice much impact difference at 50 yards, unless you are one of the top 50 archers in the world. Thus, the gimmick of weight deviation is just that, a gimmick to scare you into believing weight has a huge difference on impact. You can't even aim good enough to determine the weight differences!"
    Source: http://www.carbontecharrows.com/main/arrow-spine-weight-and-straightness/

    Well, according to Carbon Tech, seeing how the difference in weight of my ten arrows is only 4.1 grains (426.6-422.5) and not being able to tell a POI difference unless there is 7-8 grains of difference, I was just wasting my time, because I'm sure not one of the top 50 archers in the world.

    Plus, with those 420-some-odd grain weight arrows traveling a tad over 400 fps (I have a Scorpyd 160 Extreme), the trajectory is pretty flat anyway.

    So, I'm gonna just shoot and have fun.

    Bobby
     
  2. JOE PA

    JOE PA Member

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    I don't know if anything like you were attempting is a waste of time if you learn something from it. For me, it seems that spine is the big thing for crossbow arrows. I have actually had spine indexed arrows that I had to turn the nock to a different cock vane to get good spinning broadheads to shoot to the same spot as the rest of the arrows. That is with recurves shooting 340-350 so I'd guess it is even more important with a fast Scorpyd. I plan to bare shaft test a batch of BEEs I got that are not spine indexed, and see if that makes them more consistent.
     
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  3. two tines

    two tines Active Member

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    Like joe pa said, never a waste of time IF ya learn something. It seemed the weight you were adding, to achieve exact or very near weights, also was changing the FOC on arrows that had added weight. FOC will change poi.
     
  4. bunnyrabbit

    bunnyrabbit Active Member

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    I try to get my arrows near the same weight as possible. Here are a few things that can effect difference in weight: 1)not all arrow points weight the same even out of the same package. 2)if one replaces vanes, depending where they were purchased (different lengths, thickness, height). Vanes can be listed as say 4" (On my Barnett 22" Head Hunter arrows the vanes are slightly less than 4"). 3)inserts from different companies are designed differently. Some have more or deeper grooves which accept more glue. 4)excess glue when installing vanes. 5)cutting an arrow shaft a shade longer or shorter. Taken individually, its seems a very small difference, but couple a few of these examples, it will show a fair difference in total arrow-point weight. These are a few examples I have experienced when building or repairing my own arrows. All the best.
     
  5. bltefft

    bltefft Active Member

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    Thanks guys for talking to me. I rarely shoot out to 50+ yards and I have NEVER had an arrow from no Scorpyd miss the target and be lost to me. I think I was just going overboard.
     
  6. XCAL1

    XCAL1 Active Member

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    I am finding that if I shoot a field tip, it doesn't matter if it's a 100 or 125 grain, the POI is the same at my hunting range of 30 feet. This is with a soid bench rest, shooting Carbon Express Maxium Hunter arrows from my Vortex and CE Super Coil. I have even shot 170 grain field tips with little difference. But I have always tried to keep my arrows close to the same weight, the only exception is my discharge arrow that I like very heavy.
     
  7. bltefft

    bltefft Active Member

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    I have found the same to be true for me. Close in, I don't any difference on POI. And I'm thinking the 125s will sink farther into the target and be harder to pull out. Of course, for hunting I'd reckon a 125 BH would give better penetration than a 100, but since either size will do though-and-through, I'd think the flatter shooting 100 would be the way to go.
     
  8. jon.henry755

    jon.henry755 Well-Known Member

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    "Usually if the arrow is 7 or 8 grains difference you will probably not notice much impact difference at 50 yards, unless you are one of the top 50 archers in the world. Thus, the gimmick of weight deviation is just that, a gimmick to scare you into believing weight has a huge difference on impact. You can't even aim good enough to determine the weight differences!"

    This statement is both misleading and incorrect! It was written and applies to shooting arrows from a bow, not a crossbow. With a conventional bow holding rock steady at 50 yards is extremely difficult for all but the top competitive archers. This is not the case with a crossbow, especially when bench rested or shooting off any type of support, tri-pod or other devices. The net, net of it is that with crossbows we have a much greater degree of accuracy and consistency in our shooting, therefore 1 gram of weight difference make a noticeable difference in shooting performance as the distance increases.

    To your issue about having trouble getting all your arrows to remain within .3 grains (3/10's of a grain) you need to pre-weigh all arrows and inserts before your nocks are installed. Record the weight of each on paper. Then, starting with your heaviest shaft add the smallest amount of glue possible to the outside of the nock for that shaft and insert it and rotate it to it's final orientation position.

    Next, weigh it and record that weight on your paper. That is the weight that you will use to perform the same sequence on all remaining arrows. You can add as much glue to either the outside of the nock or the hollow inside of the nock to bring the weight up to the exact desired finished weight.

    I recommend using as slow a setting Epoxy Cement as you can find. This permits you to easily remove and install the nock as many times as necessary to add or remove glue and re-weigh each shaft.

    When finished, you should no more than 3/10's of one grain of deviation between the heaviest and lightest shaft within that dozen arrows.

    Last step is finding enough points that all weigh exactly 100 grains. It often takes sorting through a few dozen to find exactly what you're looking for.

    Along with spine matching and nock orientation, this weight matching process is the only way possible to achieve 3" to 5" groups at 100 yards or greater with a crossbow. Guys that don't want to go through this type of work can always contact Jerry at South Shore Archery and have him build them a custom set.
     
    Old Longhair likes this.
  9. bltefft

    bltefft Active Member

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    jon.henry I thought the statement was for arrows, not matter what shot them, thanks for clearing that up. Seems to me what you described is a real chore - I'll just get Jerry to make my some custom arrows.

    All the best,
    Bobby
     
  10. jon.henry755

    jon.henry755 Well-Known Member

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    If you owned all the equipment to build your own and understood the How-To's it would be feasible during the winter down-time to build a set or two. Otherwise, Jerry (South Shore Archery) or Dorge (Firenock) are the best in the business.

    I'm not advertising for either of these guys, they've both earned their reputations based on years of hard work serving the most discriminating shooters.

    Best of luck.
     
  11. bltefft

    bltefft Active Member

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    I have never dealt with Dorge (through no fault of his), but I have had Jerry made me arrow - he is top notch.
     
  12. Cossack

    Cossack Incurable Tinkerer

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    There is nothing wrong with the stock BEEs (.001 straightness), mine work great and are cheaper than I can make em.
     
  13. jon.henry755

    jon.henry755 Well-Known Member

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    Old formula that was derived from conventional archery, but also holds true with crossbows or anything else that launches a projectile.

    At 28" of draw length (the AMO Standard), at 60 lbs. of draw weight, at 60 yards 1 gram of weight difference equals 4" on the face of a target.

    So you can carry that formula out as far as you want to go. When shooting a bow or crossbow at much heavier draw weights, but much shorter draw lengths and longer or shorter distances these numbers can be a bit less significant. On the other hand, they absolutely prove that as ones arrow weights vary, then so does the resulting elevation on the face of a target once we get past the short distances before arrow drop begins taking place.

    Good enough has always been the arch enemy of better and best! The rest is up to each shooter to decide just how accurate they want to be.

    When you read threads on these forums about shooters who can shoot groups of arrows at 50 and 60 yards or greater because they'll destroy their own nocks or arrows, this can't be achieved unless all aspects of their arrows are very precisely matched. This especially pertains to arrow spine and weight matched arrows.

    Xbow755
     
  14. CJOttawa

    CJOttawa New Member

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    Xbow755,

    Did you mean "grain" or "gram?" There are 15.4324-grains per gram so a 1-gram difference, for sure, is going to make a huge difference. (that's ... 5% of a 308-grain arrow.)

    OK - this got wordy. I'm going to bullet point this.
    • I'm new to crossbows but have extensive conventional archery and arrow building experience over 25 years.
    • I was quite disciplined about keeping point weight within a grain.
    • Overall arrow weight to within +/-2-grains (so, max 4-grain spread between all arrows)
    • On a good day was grouping 1-inch at 30-yards (60# mild cam compound, 28" draw/arrows)
    • I see FoC and point weight as being the most critical followed by overall arrow weight.
    • Weigh your arrows without a point; shafts seem fairly consistent, at least mine are (22" Easton Headhunters) within a grain
    • Points vary in weight a lot. (up or down 2+ grains not uncommon) and this is the worst place to make weight variations as it affects spine and FoC.
    • Adjust point weight by filing down threads or adding thin washers as needed.
    OK, that's it, that's all I've got. I hope the data-points are useful.
     
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  15. bunnyrabbit

    bunnyrabbit Active Member

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    CJOttawa: Nice information. Thanks for sharing. All the best.
     
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  16. jon.henry755

    jon.henry755 Well-Known Member

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    To be clear, I meant exactly what I wrote, "Grains". I've been building my own arrows for over 40 years and brought the process of using an electronic gram scale - set to measure grains onto these forums about 4 years ago.

    In the old days, when building aluminum arrows we would do the final weight balancing when installing our aluminum inserts as our final step. In those days we used "Hot Ferrile Cement" as our glue method. We worked with a propane torch and heated the arrow shaft to insert and remove the insert to either add or remove small amounts of the fertile cement to the arrows insert. In this manner we could achieve a final weight balance of not greater than .3 grains between our heaviest and lightest arrow in a given dozen arrows.

    This process was never known or used by anybody other than competitive archers where having perfectly matched and balanced arrows was important.

    With carbon arrows the steps in the process had to be modified since heating the arrow shaft and using hot fertile cement could damage the arrow shaft. Slow set, high strength Epoxy became the solution and since many arrow manufactures were pre-installing inserts into beveled shafts, apply the final weight balancing glue to the nock end became the logical solution.

    If one is careful and takes their time, always beginning with their heaviest arrow first and then bringing all other arrows to the exact final weight of the heaviest arrow with the smallest amount of Epoxy to bond the nock, you can achieve a final weight deviation of not greater than .3 of a grain.

    Yes, that's correct, it's not much more than a spec of dust in weight difference.
    And yes, today's accurate, high end crossbows can take advantage of this arrow weight matching. When shooting at 80, 90, 100 yards or more it's a must have in order to achieve 3" groups.

    For hunting purposes, totally not necessary and not worth the time or work!

    Xbow755
     

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