jsb speed versus in flight stability question

[cavedweller]

But, what does all that really mean? Get a bunch of pellets and go test them. No free lunches.

my point is... i'm not here to feed the pellet manufacturing biz entire family, i'm here to become a better shot. That said, it shouldn't cost a fortune in time and money to find a "start" the process place to begin.
Why re-invent the wheel if the wheel is already round ? Start with that basic shape and low rolling resistance and invent the spokes and tires around it ... just my meandering mind, but, ya get the idea.

 

[18.13]

Your pellet has its best BC when shot between about 830 - 920

 

[c_m_shooter]

Interesting that none of the .177 shooters have piped in? Esp the hunter field target peeps.
I am seeing a trend here - 860 fps upwards to 910 fps. What this does is give me and others a starting point and that's really what myself and others might be looking for. I am surprised the pellet makers don't share some projected best speeds and favorite barrels by pellet type and weight?

800 to 900 fps generally, no matter the weight. Above 950 most start to have issues, but there have been a few anomilies.

 

[cavedweller]

800 to 900 fps generally, no matter the weight. Above 950 most start to have issues, but there have been a few anomilies.

interesting = sometimes its the anomalies that can give us huge insights. such as?

 

[cavedweller]

Your pellet has its best BC when shot between about 830 - 920View attachment 295027

Thank you = fantastic info - that's what i was looking for. a perfect starting point.

 

[JamesD.]

its not that a certain weight/brand of pellets likes a certain speed
its that all pellets (no matter caliber/brand or weight) dont like to go too fast,
a product of their design if you will.

so what youre going to find is that no pellets like super fast speeds,
but they have no problem with slower speeds.

but when you get the speed up near the trans sonic region they can destabilize, and thats where accuracy suffers.

food for thought lol

So wouldn’t 565fps -700 be perfect for 50 yard or less Starling type targets? I’m thinking a .30 or .357 at 600-700 with pellets would be fantastic.

 

[Mickshooter]

Ditto to TheCarFather. Sounds Right.

 

[abslayer]

Ever gun I ever had seem to work best from 850 to 900 fPS Push them farther and groups open with flyers

 

[gendoc]

.177 HW100 jsb 10.34gr @ 965fps
.22 crown mk2 compact jsb 18.13gr @ 925fps
.25 Spa M16 jsb 25.39gr @ 983fps
.30 Uragan jsb ko's 50.15gr @ 964fps
these tunes are my JSB hunting choices, i dont shoot paper
but all are 1 hole at 50yrds

 

[triggertreat]

I am not experiencing any issues with the JSB 44.75gr at 960 fps. In fact, they are quite accurate at this speed.

 

[cavedweller]

Sweet spot for starting with JSB .177 Diablo @ 13.43 gr moving around 815 FPS = giving you 19.81 FPE for HFT usa compliance.
So one pellet weight down might be a wiser starting point in .177 or 10.3 Gr JSB moving at 920 FPS or slower creating less than 19.63 FPE

 

[JungleShooter]

Here's another chart...
▪ it helps selecting appropriate pellets and slugs for a certain power settting, or
▪ it helps selecting an appropriate power level based on the amount of choices of pellets and slugs you want to have.

It assumes muzzle velocities that typically result in a fair amount of precision/ stability.

Matthias


Attachment (PDF):
POWER Choices vs. Pellets/ Slug Choices

View attachment POWER. Choose It Wisely as It Restricts Pellet + Slug Options.pdf

 

[Ballisticboy]

Be careful when looking at the values on the JSB chart. They are using reference drag laws which are not suitable for pellets or slugs. For domed pellets they should be using the GA or GA2 drag laws which are specifically designed for pellets. There are no suitable drag laws for wadcutters or pointed pellets, but again the GA drag laws are probably best. There is a prototype drag law for slugs, but it needs more data and refinement. Most people currently use the G1 drag law for slugs, but it is not good at high speeds, hence the need for multiple BC values at different speeds. The use of the correct reference drag law should result in only small changes in BC at different speeds. Unfortunately, some manufacturers deliberately use the wrong reference drag law to give their projectiles artificially high BC values.

The main problem with the JSB list is that it does not give confidence that they entirely know what they are doing when it comes to external ballistic data and trajectory modelling.

 

[SDellinger]

I shoot my FX500 at 910fps with 25.4 JSB pellets and my FX400 at 910 with 18.13 JSB pellets. The 18.13 pellets wobble some times in my videos but not the 25.4. They fly true to the target but wobble. I should shoot at a target at 75 yards to see the impact to see if the holes are elongated.

 

[Senor Ramon]

Here's another chart...
▪ it helps selecting appropriate pellets and slugs for a certain power settting, or
▪ it helps selecting an appropriate power level based on the amount of choices of pellets and slugs you want to have.

It assumes muzzle velocities that typically result in a fair amount of precision/ stability.

Matthias


Attachment (PDF):
POWER Choices vs. Pellets/ Slug Choices

View attachment 295242

Well researched and very detailed as ALWAYS! Thanks, Matthias.