FX Impact and Crown question please set me straight

[toku58]

So why is it harder to drive a .22 (25.4gr very heavy pellet for caliber) at 1000 vs a .25 (25.4gr average to light pellet for caliber) at 1000? I can probably get close to 1000 with the kings in .25 but I can't shoot a monster in .22 at that speed with the same gun, same length of barrel, same reg pressure, same hammer spring its harder to drive a heavy pellet for the caliber than it is a light pellet for a step up in caliber. I think its a surface area of the back of the pellet vs weight calculation Matt can probably explain better. 

It's easier for a gun to do your example in .25.

There are many factors that go into how a certain projectile performs. 
I was trying to answer the OP original question.
Given the unknown of the amount of air being used it is difficult to determine what makes one pellet perform better than another. 
Now depending on the set values of a certain gun. If the gun in question at it's optimum peak to propel a .22 cal 25,4 gr pellet to 800 fps. that same gun by only changing the barrel caliber cannot build up the required pressure to volume ratio, because of the larger volume.
But if a gun was pushing more air volume then the lenght of barrel could perform. And was wasting air after the pellet has left the barrel in a .22 cal. Then YES! It would do better in a larger caliber because of the coefficient friction in the barrel due to the larger caliber and potentially gain more FPS. But these are factors that in eeverey set up is always different.
The Optimum tune for that caliber will not perform as well in another caliber. (Has to do with PSI, air volume, lenght of barrel etc.....)
So depending from which facet of the diamond you are looking at this problem then it could go both ways.
BUT!
If the weight of the pellet and the FPS are the same it wouldn't matter what caliber it was. The FPE would essentially be the same just as it leaves the barrel. 

I think we're coming at this question from different angles.
Both of the theroies/answers have validity, but it would depend on many other unknown factors with the set up in question.

 

[jwrabbit123]

glem is barrel same length ?

 

[Glem.Chally]

The original question is if you have a 30gr .22, .25 and .30 and all else being equal which caliber will make the most power. The .30 will because a 30gr projectile is nothing for a .30 its going to make it scream whereas the .22 will be put putting along. Why is that if all else is equal?

Me and Matt have both given you first hand real World situations with direct comparisons. All else being equal the .25 that makes around 60fpe will when barreled in .22 make around 50fpe (just an example), same length of barrel, same reg pressure, same hammer spring adjustment = Same puff of air (or as much as the .22 can flow). 

Yes both a .22 weighing the same as a .25 going the same speed is of course the same energy, but which makes the most power at MAX, the bigger caliber will. If a gun can send a 25.4 at 1000 in .22 (56fpe) at max it can send a heavier pellet in .25 and make even more power. 65+? in .25

Yes JW same length barrel.

 

[toku58]

If the OP was asking which could potentially make the most FPE then of course it would be the larger caliber.

Possibly I miss understood whole the point of the entire thread? 
But Physic doesn't change. The factors that contribute to sending a projectile down range doesn't change.

if jwrabbit123 was asking which could produce the most FPE then yes the bigger caliber will always win.

Sorry if I miss understood what he was asking. This has taken way more time out of my life then I cared to spend.

Good luck with your calculations! 

Have a Happy Holiday!

Merry Christmas!

 

[jwrabbit123]

thanks glem and sorry all for confusion I knew I would have a hard time getting my answers but you guys came threw thanks all for helping me understand better

 

[ackuric]

The energy transfered from AIR to LEAD is proportionate to the surface area or BORE diameter as the force applied is PSI = lbs/ sqaure inch...



toku,

If you are referring to HIGHLY detuned pcp's that are set to make 25-50% of their intended power, then sure your theory may apply with loss of power due to increased barrel volume...but cmon is that practical or how most people tune pcp's? No...



I showed the math to prove it, and its how physics works. PSI is a unit of measurement. It measures how many pounds of force exerted PER inch. If you increase inches exposed to pressure then the energy transfered increases proportionally...I have a formula that predicts FPS/FPE output in a given caliber/barrel length/pressure/plenum size/tp wasted volume and a few other parameters within 99+% every time. Your 'barrel volume' is of little to no concern when the valve is open provided you have enough plenum to keep the pressure close to initial pressure, valve open time determines the majority of the energy transfer from air to pellet. The barrel volume increase from .22 19.5" barrel to a .25 cal is...12.143 cc's to 15.658, which is 28%, where the .25 cal still sees 13% more pressure over the full 100% of barrel length, I kind of think the .25 cal is always going to win unless you tilt the conditions EXTREMELY in the .22's favor...especially if you understand how barrel pressure gradients work, barrel length has diminishing returns as the pressure drops quickly upon valve closure, but that extra 13% of surface area while valve opening is more important than the 28% increase of pressure drop upon valve closure...



If your theory were applicable in any real world sense, it would not be common practice to increase bore diameter to achieve higher power...let me see you achieve ~700 fpe out of anything shy of a .45 caliber...because if your theory was correct, then a .22 cal with a heavy enough projectile would have no problem doing it...

 

[18.13]

My Crown is shooting the 34gr JSB at 850 for 54 fpe. When I put the 30 barrel on it shoots the 45gr JSB at 843 for 71 fpe without adjusting anything. I assume its because of the larger transfer port on the 30 barrel.

 

[Centercut]

@ackuric, very good scientific explanations. Hard to argue with math and science. And its proven out as theory to practice in guns like the FX Crown when shifting calibers. Maybe the doubters still think the Earth is flat? Because you know, every time the streetlights come on at my house, the sun goes down. Cause and effect....

 

[ackuric]

+1 CC, its seen through real world applications and when science/physics is applied. I think toku is just thinking down the wrong rabbit hole and many small caliber advocates may as well, but there is no denying the reason behind increasing caliber / bore diameter to achieve higher energy outputs from the same or similar barrel length / pressure.

 

[ackuric]

A little more in depth discussion....similar example but comparing pellet/slug weights.



Given the same projectile weight, the smallest caliber possible to shoot it out of given adequate form factor of said projectile, will provide the HIGHEST BC, due to having the highest SECTIONAL DENSITY. So a .22 cal shooting 25.4's should buck wind and have less drop than a .25 cal shooting 25.4's...marginally so being the BC in the .22 is .039 compared to .038 of a .25 cal...



That doesn't change the fact that the .25 cal will be able to shoot them faster...due to the already discussed reasons. Larger calibers, provided same pellet weight, will always yield more energy output provided same barrel length and pressure...unless you TILT the conditions and do a 50% or less valve opening event that does NOT pressurize the barrel equally to what the plenum is.

 

[ackuric]

My Crown is shooting the 34gr JSB at 850 for 54 fpe. When I put the 30 barrel on it shoots the 45gr JSB at 843 for 71 fpe without adjusting anything. I assume its because of the larger transfer port on the 30 barrel.

.25 to .30 cal is 20% increase in surface area / bore diameter....54 to 71 fpe is 31%...but you also increased projectile weight from 33.95 to 45 which is going to give the remaining change in power increase...I bet if you shot a 33.95 out of the 30 cal (I know that weight isn't available but if it were..) you would see roughly 20% increase from 54 to 65~ fpe.