I do it.

You can even put in your own weight in the formulas and calculate its approximate speed. For example, using the y=-0.3606(x) +527.1 formula for the 135E, if I were to shoot bowmanmt's 474 gr arrow in my O135E, it would calculate out to about 356 fps.

 

Extrapolations … be it with bullets or arrows: "must be verified on the range."

 

I just sight in for 20.

Then move target to 40.

Then shoot at a spot using the 20 yard aim point.

Measure the drop.

Note to self: Use a big target or risk arrow destruction. Lol

 

I know - I verified my drop at 40 yards with a 30 yard red dot was the same as the Hawke chart at 4.7". But the drop at 50 yards was over 12" so I chickened out.

I do it.
View attachment 129844

You can even put in your own weight in the formulas and calculate its approximate speed. For example, using the y=-0.3606(x) +527.1 formula for the 135E, if I were to shoot bowmanmt's 474 gr arrow in my O135E, it would calculate out to about 356 fps.

Great chart Sam - so the loss in velocity to shaft weight is linear - interesting. I wasn't sure since trajectory is parabolic but that's good to know what to expect if I need to shoot some harpoons this fall.
.

 

These charts and others are available at "Crossbow Acadamy" .

http://www.bestcrossbowsource.com/guides-articles/

Some of these charts are interactive, so move yourself around to match your specs.

The best learning & remembering comes from compiling your own paper charts.

 

I would have to shoot it. Thats just all there is to that. Knowing i can simply rotate the shaft and maybe cause it to hit high. Would blow the chart out of the water. I guess if you have extremely fine tuned matched arrows. The chart might work. But once you change the FOC you change how the arrow behaves. Yes im sure you can get ball park baseball size groups. And the chart might work to give you a idea. But id never carry it hunting without shooting it. And if i shoot it i really don't need the paper work.

But hey try it and see nothing wrong with playing with new ideas Right .

 

But hey try it and see nothing wrong with playing with new ideas Right .

Sort of like using the vanes to help the broadhead's blades to cut organ tissue?
.

 

A major factor is power stroke. The longer the power stroke the less the drop in speed with increased weight.
Additionally, the cam design plays a factor as %age of draw weight throughout the launch affects speed.
Still, it’s very doable but a bit involved.
Useful? That’s another question. I’ve yet to have that much spare time.

 

If i recall and its been awhile . But im pretty sure the ramcats shot 1" higher than field points. Using the same arrow.
And the G5 striker mags shot 1" lower than field tips again shooting the same arrow. I have 3 out of a Doz arrows that shoot 1" lower than the others now from both 400's. I just adjusted my scope up 1/2" no big deal. I was using the Excal 380 when i shot the fixed heads above.

So broad heads matter too.

 

If i recall and its been awhile . But im pretty sure the ramcats shot 1" higher than field points. Using the same arrow.

4 years ago I shot a field point and then a Ramcat at 40 yards off the tailgate on my pickup. The Ramcat hit just over 1" low from my Ventilator using the same shaft.

 

Hi tpcollins,
In your opening thread you mentioned the fact that the manufacturers specification for your crossbow, using a specific arrow weight was 380 fps., but when you tested your crossbow with the same arrow weight your results were 384 fps. A difference of 4 fps.

I've seen similar and greater differences many times, just by changing a bows or crossbows string and / or cables. As the material composition of strings or servings change it has a distinct impact on the overall velocity performance of these units.

While I agree that it's possible to develop charts to approximate certain speed or POI factors on ones crossbow, it must be understand that these chart calculations are approximations, but are subject to variations, such as those which I just outlined and a number of other factors. Altering the length of your arrows vanes or the height of your vanes will create greater or slower velocities. All of these things will impact POI especially as distances increase.

Regards,

Xbow755

 

Hi tpcollins,
In your opening thread you mentioned the fact that the manufacturers specification for your crossbow, using a specific arrow weight was 380 fps., but when you tested your crossbow with the same arrow weight your results were 384 fps. A difference of 4 fps.

Regards,
Xbow755

The 4 fps difference could be from the +/- 1% accuracy of the chrony.

I still like Sam's chart
.

 

Joe - my 1" low with the Ramcat was at 40 yards, at what distance was your 1" high?
.

 

You seem to be more of a reader vs someone that tries things. You need to read about arrow Nodes and there effect on the path a arrow chooses. Then try and understand when the arrow flexes. The path the arrow chooses is controlled by how much it flexes how it flexes and how quickly the vanes correct the flex. This can very from bow to bow arrow to arrow and components used affect the path the arrow chooses. Even bows shooting the same weight arrow the same speed. Its how it gets the speed controls the flex then in turn the path the arrow chooses.

This is why we need to know where the stiff plain is and where the weak side is. And flex accordingly this gives us a great starting place. But even here matching the spine as closely as possible is even better. Then once you have a truly good shooting bow. You can see the differences slight changes make in poi.



Like i said nothing wrong with trying stuff. Have fun .

 

You seem to be more of a reader vs someone that tries things.

Well that is one way of learning things rather than listen to a bunch of babble on hunting forums. Compared to when I started bowhunting in the mid 60's, a 1" variance between a field point and a broad head would have been considered outstanding at 40 yards. I don't think I could come anywhere close to that back then but I still managed to take deer.

I read somewhere that you used to build recurve bows. I assume you used cedar arrows (could have used aluminum as well). What type of grouping did you shoot back then and what variance did you see when going from field points to broadheads back then? Were you shooting like Byron Ferguson back then?

With todays velocities, equipment, and optics, we should have no excuse for not being able to shoot sufficient enough to take deer. I always verify reality versus the theory associated with ballistic charts, but I think it's bit odd to piss and moan about a 1" variance at 40 yards.

But mainly, I prefer to get an idea ahead of time of what to expect with trajectories. I have already lost 3 Tapps or so in the past and I don't like doing that.
.

 

I shot carbon latter on more than anything. After i built the bow I would shoot a bare shaft on a bare shelf. I was trying to here the nock of the arrow ticking the shelf. Once the sound of the nock stopped i stopped sanding the limbs. I knew tiller was dead on. Then i covered the shelf. Then using those Nodes . i shot a bare shaft arrow that was to weak. Im right handed and shot fingers so it over flexed and shot to the right. I cut a inch at a time off the shaft until the arrow hit a little right. This is called training the arrow LOL. I left it right because the feathers would cause it to act stiffer. Leaving me with a arrow that shot where i was looking. I shot those bows very well thank you. After i learned how to use those Nodes by controlling the flex of the arrow.

And i trusted in the force .

If your losing arrows. You can always move the target 5 yds and not take such big bites . Thats how i learned to shoot a trad bow little steps.

But hey you don't need my permission. Make your chart and save those arrows.

 

Rt and TP ,you should really just get hitched. Then you could meet each other every morning and have hall sex......
You both jump on each other’s thread and bait The heck out of each other, I know rt will always say it’s not my fault but to me you’re two peas in a pod.
Plenty of knowledge from both of you ,if it was just limited to that and forget yelling at each other to “get off my lawn!!!!!
Carry on screwing up yet another decent thread...
Come on hunting season,please!!!!!!

 

Good post.

 

Ok fine lets see who starts the next one.

Ill give my word ill never post on a thread TP starts or read it. So far as i'm concerned its over.

 

Hey, I made one of those speed charts while sitting out at the bench of my rifle range shooting different arrows through my new Ventilator Extreme 175 and my Ventilator 80 one nice day back in 2015.

It is a quick on the spot graph I made up, and it ain't pretty. I was going to make it more professional looking, but it was really for my own use, until someone asked me to post it back then. Then Sam did a real professional looking one of his, and I never bothered to do mine after that.

Like I said, it ain't pretty, but it has all the information as far as speed of arrows in the same chart. All my other bows would be right in the middle if these two.

The speed is mostly linear, until you start getting up in the 450+grain arrow weight, then the efficiency actually starts inching back up. I have since charted numbers on some of my other bows, and also figured average FPS loss to every grain of added arrow weight.

I haven't ever charted arrow POI drop over the yardages, but that could be some useful information is you don't have too many bows to remember like I do. Sometimes, you can have too much information bouncing around in the old noggin for your own good, if you know what I mean.

Here is my old chart. Don't laugh!

 

Hey, I made one of those speed charts while sitting out at the bench of my rifle range shooting different arrows through my new Ventilator Extreme 175 and my Ventilator 80 one nice day back in 2015.

It is a quick on the spot graph I made up, and it ain't pretty. I was going to make it more professional looking, but it was really for my own use, until someone asked me to post it back then. Then Sam did a real professional looking one of his, and I never bothered to do mine after that.

Like I said, it ain't pretty, but it has all the information as far as speed of arrows in the same chart. All my other bows would be right in the middle if these two.

The speed is mostly linear, until you start getting up in the 450+grain arrow weight, then the efficiency actually starts inching back up. I have since charted numbers on some of my other bows, and also figured average FPS loss to every grain of added arrow weight.

I haven't ever charted arrow POI drop over the yardages, but that could be some useful information is you don't have too many bows to remember like I do. Sometimes, you can have too much information bouncing around in the old noggin for your own good, if you know what I mean.

Here is my old chart. Don't laugh!

View attachment 129890

Vent, great to hear from you, please don't be a stranger! You have way too much knowledge to share...especially regarding Scorpyd's!

 

I think pretty well everyone agrees that anycrossbow shooting 350 FPS with a 400 grain arrow will be reasonably efficient out to forty yards,
It’s after forty that most arrows need that speed to reduce the drop .....
Misjudging distance by three yards at a thirty yard target isn’t nearly as critical as a three or four yard misjudgement at sixty. IMO....
That# where four fifty FPS shines....

 

That's where a Leupold Vendetta really shines - out to 75 yards.