Relationship of FPS to Accuracy?

[tor47]

It may be only 8% faster, but energy is is a function of the speed squared.  So moving from 850 to 920 FPS increase the FPE by a little over 17%, not just 8%.

Of course accuracy is most important - 17% more FPE in a missed shot does no good.  But speed and energy are not the same.

Well you are right, did not thought about that:-)

[Ribbonstone]

A case against maxi-maxi speeds.


If accuracy isn't any different,even with the up-powered rifles,sill end up with a choice of shot count vs. energy....and how much of one is worth how much of the other.   The last 5-10% or so of velocity can be quite costly.

BUT...if adjusting for the most you can get out of a system...then the most is what you want, not "a bit less".  Understand that urge for the MAXand how it leads to the little changes in PCP modding to getanother 5-10%.

Buteven if the "max of the max" is the goal,  it's got to stop somewhere...or you'll be modding/adjusting and not out shooting/huntinglooking fgor that loast 5%...then 3%...then 1% "better".

At some point, will either call it "done"or accept that it'salways going to be a work in progress...at least until you do something that screws up what you already did.


Lets test-post that: If you have a "maxed out"PCP...is there really NOTHING you could do to make it even faster?....or did you just blow a whistle and call it "good
nuff"?

Even on my "fast ones", tend to back off bit....usally not much.  Choice between 64 foot pounds/6 shots (call that 34gr. @922fps) vs 58 foot pounds/ 11 shots (call that 34gr.@ 877fps) seems pretty easy for me.

Bigger air volumes/longer shot counts/but the proportion remains the same...I just tend to hunt with the thin/lighter PCP's.

Don't keep many 22's or 25's jacked up in power....just not over run with larger critters that need shooting.... so even the hot-rods are not at absoulte max power.

FREELY ADMIT...the paper balistics  are worse for the 877fpsvs. 922fps version.

BUT (good assumtion that I ran the two (877 vs 922fps) through calculators) what is the real world difference?

1. You have to either adjust the scope up or hold off at 100 yards.  If you know it's 100 yards from your sight in,how much real world difference in clciking up/holding off 15 1/2 inches than 17 1/2 inches?

2.Energy at 100 yards?  No dobut  29 1/2 foot pounds is more than 26 1/2footpounds.  Doubt by use that it's a serious amount of difference.

3. Windage (using a mild 5MPH wind from 90degrees to flight line)...the difference in  like 1/4th inch.
(this is the one that decided me....can get a ranage finder...can't really get a 100yard average speed wind finder.)

4. Shot count?(in the little air tube example).   Nearly 2X the shooting before stopping to refill.

NOPE...not going to change the minds of power-heads.  A small dfiffernce looms large in their minds....doesn't loom large in my mind. 

Once you start getting to holding or scope adjusting off, it's  a matter of how well you can judge  the range in order to figure out the right hold-off.

[JungleShooter]

I like your incisive thinking and your carefully weighing the pro's and con's, Ribbonstone! 👍🏼


🔶 Often I play these what-if games, pro's and con's, like:
➔ What if I increased the power of my PP700 from 12FPE to 16FPE....:—How much less wind drift would I get, at 20y and at 40y?—How much longer would my point blank range be?




Ribbonstone, I'd like make a case in favor of maxi speeds — but only for one particular application... — otherwise I very much agree with you, the performance difference for upping the power are often much less than I imagine — until I run the numbers.... 🙄


🔶So, lately, I have been looking at the expansion of hollow points — pellets and slugs.
And here the chasing of max. power is quite relevant —
because hollow points have a need for speed — otherwise they don't expand in the quarry (and using them makes no sense the first place).


Look at one of the expansion tests Rick Eutsler ran (pic below): This particular pellet needs somewhere around 800fps for a healthy (and deadly) expansion.


Because a hollow point pellet has a low (or abysmally low) BC it needs to leave the muzzle pretty fast, as it sheds its velocity rather quickly.
For example, if you wanted to reach quarry at 30y with the pellet in the pic — it needs to leave the muzzle with 955fps MV to still have 800fps target velocity (TV) in order to expand.... 


Just some thoughts going through my covid-ized brain.

Matthias

[PikeP]

What if 920 fps shoots .25 MOA better at 100 yards than 877 fps due to harmonics? What about the application for br shooter versus hunter versus casual versus someone who won't shoot the gun for more than a year before moving onto other things...

What if 920 fps isn't considered 'hot' for your gun being it has plenty of barrel and plenty of pressure and your ammo weight is within reason, and you want every bit of the flattest possible trajectory, even for shots within 30-70 yards...

26 vs 29 fpe at the target is a difference of 10%, what if that is the difference between breaking the bone and hitting the off switch, and not...well that depends on application and game size, which varies for all, so no need me bringing in my personal needs which yours may be different, so I'll leave it simply at just that...be responsible and ensure enough terminal energy to effectively down game without any shadow of a doubt...

Its not one size fits all here, and what suits one person, may not suit another, and for very good reason...there really are two sides to every story, or to every argument, and when you bring in two sides (880 fps vs 920 fps) then you can absolutely argue for or against either without being wrong in any technical sense...

[Ribbonstone]

What if 877fps shoots 1/4moa better?...would you give up the 10% difference for "extra" accuracy?

Takes a whole lot of shooting paper to get a valid analysis of 1/4MOA long term difference....but it could happen either way.

Here is where I do differ from most posters.

Don't usually shoot long range.....more of a get up close kind of hunter...a "grunt"rather than a "sniper".....so the higher powered airguns don't really get used farther away. They get used on larger critters no farther away than what the lesser powered airguns are used on little critters.