Best velocity for shooting slugs vs. pellets

It seems to be common knowledge that shooting diablo pellets between approximately 825 - 900ish is the highest velocity to get really accurate results. I believe this correlates with a percentage of the speed of sound. With 22 lr., match quality ammo is usually shot between 1050 to 1150 (still sub-sonic). So this leads me to believe that spin stabilized slugs, with their higher BC, should have a higher velocity threshold before becoming inconsistent. Somewhere between diablo pellets and 22 lr. bullets. Is this true, and if so, is that high end velocity a known number? I'm thinking we'll know soon enough once all these FX slug barrels hit our shores!
 
Hummm, not an aerodynamicist but one explained it to me that the limiting factor on pellets is the drag stabilization of the wasp waisted shape and at higher velocities the turbulence behind the pellet increases and becomes so chaotic that it starts whipping around and actually 'the tail wags the dog'.

A slug is usually heavier (less effected by the turbulence behind it) and it's different shape gives a different and better airflow at higher speeds that has less turbulence then the pellet shape. Spin vs velocity is more determinant on loss of stability at longer ranges, which is why even bullets that are 'stable' at short ranges become unstable as they slow down and start tumbling, even though the spin remains relatively unchanged.

There is a HUGE amount of ballistics research data on the web done by US Army and other researchers if you look for it. It's actually fairly well understood and published and is an exact science, not guesses.


 
A short answer to your question is that I've found that slugs have several speeds that 

they seam to perform well at for a slower speed 860-880 is ok but 935 is a better speed

for most slugs , then there is a speed at 980 fps that really seams to do well for many of

the slugs that I shoot , then there is another plateau of a speed of 1040-1060 this speed 

does very good at longer distances . 




 
A short answer to your question is that I've found that slugs have several speeds that 

they seam to perform well at for a slower speed 860-880 is ok but 935 is a better speed

for most slugs , then there is a speed at 980 fps that really seams to do well for many of

the slugs that I shoot , then there is another plateau of a speed of 1040-1060 this speed 

does very good at longer distances . 




Seems to be a little more complicated than just "Yes they can be accurate at higher velocity than pellets". Very interesting
 
Reading the following comments to mine I think one thing was never mentioned.

Pellets seem to fly best at 850 to 900 FPS max and become more and more unstable at higher than that, losing accuracy.

Slugs/bullets are either accurate or not from about 700 FPS on up to 1050/1100 FPS until they get to the trans-sonic region, ie: the 'sound barrier'. There are 'resonance zones' where accuracy might tighten up SLIGHTLY but that has more to do with the gun than the projectile in my experience which is why you can take a slug in its poor performance range and fix that by changing the frequency / resonance of the rifle by dampers on the barrel, stiffening the barrel differently (sleeving or tensioning for example) or bedding which is not much paid attention to in air rifles because hold changes have much greater effect.


 
Read the BB Pelletier series on velocity vs. accuracy. Goes back to 2011 I believe. Casts some doubt on the "common knowledge" about velocity and accuracy. Specifically, he found one light diabolo pellet that shot it's best groups at nearly 1200 fps and was less accurate at lower velocities. Several others also did not suffer accuracy loss in the trans sonic zone as "expected". Seems that if the issue were generally applicable to diabolo pellets and higher (trans sonic) velocities then those results should not have happened. Maybe there is some other cause for the issue, maybe increased harmonics with higher velocity, maybe specific pellet for gun stability, or maybe something still not understood.
 
Generally the most accurate rifles that shoot slugs are ones that keep the slug above super sonic speed during its duration of flight thus reducing destabilization during transonic stage...those rifles are pushing slugs at 3000-4000 FPS....slugs are SPIN stabilized where as diablo pellets are more DRAG stabilized...trying to get the accuracy from slugs at just below transonic is kinda silly when they perform best while shot and staying above it...sadly for air rifles thats a bit too much to ask...



Best velocity for slugs = 3000-4000 fps

Best velocity for pellets = 600-1125/1150~ fps depending on your altitude...



Just my opinion :)
 
Slugs have been around since before you and I were born, even for air guns...what I stated is just the realistic truth for the two projectiles, I never said slugs can't be shot at 1000 fps, heck even handguns shoot slugs at that speed, but is it the most optimal? the most accurate combo? ....OP asked the best velocity for slugs and I gave him my opinion, if you do your own research on the most accurate slug shooting guns be them PB or air gun, you may or may not come to the same conclusion...but don't take my opinion out of context and claim I said slugs can't be shot out of airguns...
 
Muuuum, going to disagree a bit there with an explanation...

I have been shooting for 54 years and have shot MORE than a ton (literally several) of cast bullets and jacketed bullets out of PB rifles, pistols and revolvers and in my 'Magnumitus' phase was shooting those 3000 to 4000 FPS velocities (I had every Weatherby, Remington and Winchester Mag cartridge rifle ever made and usually ended up only keeping the action and rebarreled and restocked for long range shooting) at VERY long ranges of 1000, 1500 and even 2000 feet and I ABSOLUTELY can swear that the sweet spot for bullets is NOT 3K to 4K as currently constructed (even the mono-copper bullets). I also shot BPCR Big Bore for years using cast and paper patched bullets and got some of my best accuracy from them around 2K, better than many 'modern' centerfire cartridges ever dreamed of. I've shot NRA High Powered rifle, both rifle and pistol Silhouette, combat pistol, small bore benchrest, etc... shooting has been my life, all my life since my dad got me reloading at 10 years old

So the high speed is doable yes but it is a lot easier to get accuracy at UNDER 3K than over.

To shoot that much I had to reload (although I did buy factory ammo to compare too at times) and I learned to make any rifle much more accurate with tailored loads than factory ammo. Most rifles sweet spot in accuracy is not the max but usually was right around 90% of max by the way, no matter what power level of the cartridge. In Simi-automatic pistols and revolvers the same seems to hold true. I did a lot of load development using a Ransom rest which holds the hand gun, not the person, so as to take the human variation out of the equation and again, I learned that there is no 'best velocity' for any bullet but slower, IE whatever the cartridges max was, the most accurate was the 80 to 90% load(s)

Now I have left PB entirely and {for the challenge} only shoot PCPs which due to the physics barely reach supersonic and use a lot of air to get there and in my dozen of guns find again that a little slower is more accurate than the gun maxed out (and I have 4500 PSI [instead of the stock 3000 PSI] custom Texans in .457 and .357 that are a LOT more powerful than a stock rifle as just one example where it shoots a little better backed off a tad.)

So my take is that there is NO best velocity for BULLETS, but you can push them too fast FOR THAT PARTICULAR GUN TO SHOOT ACCURATELY. And in the lower regions of 750 to 1050 for subsonic and 1200 to 2600 for supersonic is easier to achieve accuracy in the total system of gun, cartridge and bullet.

In my 'slug dedicated, chokeless' air rifles (which I have come to love, strangely enough) slugs can do just as well in accuracy in the 'quality' rifle at 600 as at 1000, but I don't usually tune in the lower ranges because who wants to bother with the mortar trajectories the slower speeds give.
 
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Thanks, lots of knowledge around here, learning a lot

I wonder... It is correct to assume with airguns slugs (need to be precise) that as long as you stay low the sound barrier (in fps) is all good. I imagine if you shoot over SB and in the trajectory the slug slows down below SB, it will be less accurate than if it stays in or out the SB all the way, right? (or wrong?)
 
I'm shooting @D-Rigs 34g Varmit knockers slugs out of my .25 Taipan veteran long at 872 fps and got a 10 shot hole & hole at 50 yards....unfortunately I have gotten the chance to shoot them at 100 plus yards but I'm sure they would group very well...
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This is a older tread, but for interest sake. My rifle like .217 slugs, but it seems to shoot the .216 KO slugs quite good if they go slow. If you look at Strelock, you will see that a KO slug at 760fps wil give you the same trajectory as a 18grn Jsb pellet at 900fps. The slug actually improves at 100m with less drop than the pellet and is much less influenced by wind. I zero my gun at 50m. 
 
Hummm, not an aerodynamicist but one explained it to me that the limiting factor on pellets is the drag stabilization of the wasp waisted shape and at higher velocities the turbulence behind the pellet increases and becomes so chaotic that it starts whipping around and actually 'the tail wags the dog'.

Exactly right. It is the same effect as turbulance behind a pier piling scowering the piling clean.

Little "tornadoes" are formed behind the pellet attached to the skirt as it passes through the air. When one of them lets go it gives the skirt a little "thump" and causes the pellet to rock. That changes the orientation of the pellet a bit and pushes it just a little off course. Rinse repeat all the way to the target.

Same exact thing is what makes paintballs so inaccurate even if you shoot them in rifled barrels. It's been a long time since I played that game but fifteen years ago I built up a maker that was state of the art for accuracy and the best you could get out of them then was about an inch a yard. So a 30 yard group would be about 30 inches in diameter... so on. You make up for that error by shooting lots of shots.

With a paintball the little "tornadoes" just break free from the ball at different points on the back and cause all sorts of havoc.