Question regarding angle of entry of bolts on targets

[Dr Ignominious Death]

I sighted in my new crossbow this past week at 20 and 30 yards. What I noticed is that my shot placement is pretty accurate and I'm satisfied with my scope settings but one thing I noticed is that my bolts seem to enter the target at a slight angle; the bolts are sticking into the target at about a 20 degree angle from my direct line of fire.   What is the implication of this angle, if any?  Does this slow the speed of the arrow or have any bearing on it's ability to take down a deer? If anyone has experience with this, is my bow limb off center? (I measured the limb and it was as close as possible to even). Am I using my cocking device inappropriately and pulling the two sides unevenly? 

 

Thanks for any input.  This may be completely normal but my concern is I am loosing FPS and killing power. Thanks.

 

[jjb4900]

I know nothing about crossbows or if this is normal for them, but I'm pretty sure that would be unacceptable with a longbow........you don't want your arrows hitting your target at an angle.

[G-Man]

your either not cocking string correctly , or spine of bolt is to stiff or too flexable, or your point weight my be to light.

[moog5050]

I have no idea how to tune a crossbow, but it sounds like you are fishtailing.

[Culvercreek hunt club]

I sighted in my new crossbow this past week at 20 and 30 yards. What I noticed is that my shot placement is pretty accurate and I'm satisfied with my scope settings but one thing I noticed is that my bolts seem to enter the target at a slight angle; the bolts are sticking into the target at about a 20 degree angle from my direct line of fire.   What is the implication of this angle, if any?  Does this slow the speed of the arrow or have any bearing on it's ability to take down a deer? If anyone has experience with this, is my bow limb off center? (I measured the limb and it was as close as possible to even). Am I using my cocking device inappropriately and pulling the two sides unevenly? 

 

Thanks for any input.  This may be completely normal but my concern is I am loosing FPS and killing power. Thanks.

what is the target and are they  consistently tilted in one direction?

[Dr Ignominious Death]

"Fishtailing"- I knew there was probably a technical term.  Here are my specs: carbon Piledriver shaft 20", 100g field point tips. Target is a foam/styrofoam target.  First shots were cheap stock arrows where the fishtailing was much more consistent and worrisome. The tail would be left of the of the point of impact. I switched to the pile driver arrows with field points and felt they would still fishtail left but not to the same degree. Below is a photo of the piledriver shots at 30 yards. Looking at the picture, the fishtailing doesn't seem as apparent so I may either be hallucinating the degree of fishtailing because I was initially concerned for a possible bow defect and there is no actual fishtailing with the higher quality arrows OR the picture angle is deceptive. Thanks. 

 

 

[G-Man]

the pile diver shafts are probably stiffer , you might want to bump up to a 125 grain tip and try it, photos can be decieving you can tell the difference in person much better. 

 

[nyslowhand]

NO, this is not normal! Sort of goes back to paper tuning a vertical bow for just this issue.

 

If this is a decent, "name brand" Xbow, shouldn't be a mechanical issue with assembly, limbs or cam timing. Disclaimer is, a lot of Xbows are made in China. More than likely you're not loading limbs evenly with your manual cocking method. Tendency is to pull harder/more with your favored arm. Some rope cockers have rollers that compensate for just this issue.

 

Other than that, can revert back to any vertical bow's arrow selection &/or tuning. Mostly personal preferences! Depends on the Xbow's setup, bolt/arrow selection, vane length, broadhead that your Xbow shoots best. A different vane length may work better for you, either shorter or longer than the PileDriver vanes Lots of good info on the web, especially the better, strictly Xbow forums. Their members have years of experience to share!

[Dr Ignominious Death]

Thanks for the info everyone.

[Kodabow]

Sometimes the internal construction of a target will cause an arrow to shift at impact --- but any instability at 20 - 30 yards would come from (1) arrows themselves that do not fly in a stable manner (2) arrows coming off the crossbow rail in an unstable manner caused by either a. cams out of timing, b. one limb stronger than the other or c. possible cocking errors. Instability that far down range really suggests arrow problems to me since 30 yards should be plenty of time for a good arrow to recover and correct any launch issues.

This instability will significantly reduce penetration on a game animal at impact and is very undesirable. Adding a heavier broadhead could make a light, whippy arrow flex even further and dance around but the idea of more front end weight is generally a good idea for flight stability on a well built arrow. You might like this video and check your balance point (FOC%) Forward of Center Percentage on your arrows. Hope this is helpful.  Chuck @ Kodabow Crossbows

https://www.youtube.com/watch?v=Qj73q2YgD3I

[NFA-ADK]

I often see arrows in the target that look like they did not impact correctly but usually it is cause by a damaged internal target and not arrow flight like Kadabow stated above.  Good luck.  Keep us posted.

[Doc]

I have no idea what would cause a crossbow bolt to not enter a target in a straight head-on fashion. But even though you seem to be getting consistent contact with the bullseye, I can say that it likely will cause penetration problems. I would guess that it is something that needs an answer and a fix. 

[sits in trees]

Crossbow manufactures all have a recommended arrow they want you to use. Weight and spine are important due to the short power stroke. Are you using the manufactures arrows. All this being said I noticed the same thing with both of my Excals to a small degree, they seem to lean right at 20 yds but hit square at further distances. It doesn't effect accuracy at all and I haven't seen anything that would indicate penetration problems.

[biggamefish]

In traditional archery we deal with this all the time and it is usually a spine issue.  I think it goes if it is knock left you are stiff in spine (add weight to the front) Knock right you are weak in spine (take weight away).  You can add weight easily by just changing you field point.  Three rivers sells kits from 100 grains to 300 grains.

 

Link= http://www.3riversarchery.com/Screw-In+Field+Point+Test+Kit+-+1132_iCF-T_baseitem.html

 

I would think with the bolts being so short you could get away with some good weights up front of those little arrows.

 

Hope this helps.

[Kodabow]

biggamefish --- good post. We teach traditional archery at our facility where we make crossbows. You had us thinking. We enjoy the discussion. Here is another perspective.

Unlike vertical traditional bows, there is no riser for a the short crossbow arrow "to go around" as the arrow travels forward..... and a good crossbow arrow should be strong, straight and firm with no " flex" moving down the rail and will leave the crossbow like a laser. This is helped by the fact that most crossbow arrows are 20" in length and just like in traditional archery, shorter arrows flex less. The spine physics don't apply in a crossbow the same way they work in a traditional bow. Some compound crossbows get out of timing and will cast the arrow sideways at launch and it will take some distance for the arrow to stabilize ----- and if the arrow is designed OK with a high FOC% (we like 18% in a crossbow arrow while 10% is fine in a vertical bow) FOC% = Weight Forward of Center Balance Point...... the arrow will stabilize. Here is a link that shows a crossbow arrow moving through a soda can in slow motion at about 12 yards after being shot from a Kodabow.....it is filmed at 10,000 frames per second and its about 10 seconds into the video.

A traditional arrow would still be moving in a sine wave at that distance while a crossbow arrow should be very stable as shown.

Link: https://www.youtube.com/watch?v=kbU7YenN_Do

So in summary, I think when you have this issue with a crossbow it is a bow timing problem (cams out of timing in a compound bow or one limb stronger than the other in a recurve crossbow) especially if the arrow is always canted the same direction .....but if the arrow is canted in random directions, it could be simple arrow instability caused by failing to have proper FOC%.  What do you think?

[biggamefish]

  You bring up a good point with no riser to go around.  Plus you are getting a very straight push with the string on a cross bow.  I can see how a tiny bit of adjustment on a cam would throw the arrow a little.  

 

Here is my question and I am not familiar with the new technology so bear with me.  When you are using a recurve style crossbow what stops the string from centering itself on the holding mechanism?  I know there would be a lot of tension on the sting but i would think with vibrations of walking the string would right itself to the center and wouldn't cast the arrow at an angle?

    

[Kodabow]

What happens is that the crossbow bowstring stays centered on what we call the "String Catch" when the bow is cocked.

So you are correct about the pressure at the center serving. Once there and in place, the bowstring doesn't slide around left or right. This doesn't come in to play too much as long as the shooter replicates his cocking method every time. Some shooters will mark their string with white paint to ensure it is in the trigger group at the same place every time but I have never found the need to do this personally. We have seen a shooter buy a compound crossbow one year ----- but the next year ---- it is throwing the same arrows "funny" for the first 20 yards and then they stabilize. Same bow - same arrows. What happened?  during the off season, cables and strings stretched and the bow's timing at the cams was no longer coordinated.

In a recurve bow, the limbs will always move the same way ---- even with a string change. However, if the bowstring starts in one place and as the bowstring comes down the rail, has some left or right movement at the center serving because the limbs are out of balance as the bowstring finishes its travel down the rail, --- I think it is like a golfer putting some spin on a golf ball ..... (in this case, the rear nock) that will cause some "jump" as the arrow leaves the rail which is undesirable.

Now most hunters will not even get down to this level and many will not even notice it ----- but our limbs and string on a Kodabow will travel straight down the rail --- and an easy way to check this is to look at the string wear from where the "string catch" releases the bowstring in the trigger group. There will be a mark on the center serving from the friction at release. If that mark is centered on the rail when the bowstring is fully relaxed after the shot...then we can confirm that the string was centered at both the beginning and end of the launch sequence. The slow motion video in the link above a few posts earlier is pretty insightful. If you get a chance to look at other bows in slow motion, you might see amazing things ---- like extreme movement in the scope rail for example. 
Chuck at Kodabow

[biggamefish]

Hey Chuck,

 

  Thanks for taking the time to explain.  All good knowledge to have and it all makes perfect sense.   I can relate to a lot of it from being in the traditional archery field.  It might be slightly different in the approach but it goes back to the same basics.

 

Thanks again.

[Kodabow]

BGF,

Advances in archery are interesting and sometimes not really advances at all ---- but I agree completely that most of the knowledge goes back to traditional archery. There is nothing better than a helical fletched traditional bow arrow. Having that background helps us build a better crossbow (I think.) With a crossbow - we can learn more about the technical performance (arrows for example) since we can nearly take the human variance out of the equation when shooting from a bench. I could never shoot my recurve into the same hole at 20 yards but with a crossbow, I expect to do it everytime (from a bench)and not be off more than 1.32" if even that much. So being able to measure down to that level can quickly demonstrate which arrows fly better, whether to use brass or aluminum front inserts etc. --- so for the real technically minded individual, there can be a lot of experimentation and satisfaction. Chuck

Edited July 17, 2014 by Kodabow