Some interesting observations concerning pellet head sizes.

[K.O.]

For my purposes, fun does not consist of countless hours looking in the wrong places for improved accuracy!

For me, an ideal AR would be perfectly accurate by itself - with all inaccuracy attributable to the shooter.  This would allow one to focus strictly on technique, with confidence that no miss was due to the gun.

The famous Feynmann speech on "Cult Cargo Science" sums it up better than I ever could:

http://neurotheory.columbia.edu/~ken/cargo_cult.html

First you have to know enough to know that it is voodoo... anyone can tell you they have that rifle to sell you, do you know enough to know how far from or close to the truth it is...

[K.O.]

And that perfect rifle will have the perfect pellet size that is physics... it is just a matter of tolerances...

and then there is purpose

https://www.pyramydair.com/product/daisy-match-grade-avanti-853?m=145

a choked barrel that deeply engraves the pellet and sends wadducters out at about 450-550 fps is great for 10 meters and not so good for distance...

or hunting...

pellet head size is not junk it is a tool that sometimes helps... especially for those that enjoy getting their 100$ build to perform and take their joy from that instead of buying a Styer which will have their small deficiency's also...

 

[DOKF]

I appreciate that Kirby.

However the variable to be evaluated is pellet diameter and its effect on accuracy.  Not barrels.  Not shooting technique.  How do you evaluate one variable?  Hold the others constant and change that variable, then look at results. (vary independent variable and assess dependent variable)

Michael's testing comes closer to eliminating non-pellet diameter variables than others here.  (Ideally a machine-airgun, with no human-hold factor, no variation in air pressure, clamped perfectly on target, is used to test ONLY pellet diameter vs POA/POI)

What may work in your hands, or mine, isn't science. Even if you win competitions - there are many factors at work.  There are other venues  for elucidation of truth, such as religion and love.  We may prefer them, and they may work for us personally.  But they are not science.  And for engineering/physics - which is what shooting is* - it's hard to trump science.

*Albeit with a psychological overlay

Holding all but one variable constant is not always the most practical scientific method, nor the most productive.  In a multidimensional experiment, the true maximum or minimum may not be evident from explorations along a single dimension.  Sometimes it is faster and more productive to conduct a statistically designed multi variant experiment (Statistical Design of Experiments, often called SDE or DOE). 

Often a statistical analysis of archival data (data mining) can yield similar results as a designed experiment, especially in cases of a large number of random experiments.

While this thread topic was started to compare pellet dimensions to accuracy, that is a limited experiment leading to limited results.  The pellet dimension on its own is not important without comparison to other factors such as barrel diameter, rifling, acceleration, muzzle velocity, etc.  As stated many times, each AG is slightly different.

If you wanted to explore America, but limited yourself to only one variable (say I-5), would you see all the best places?

[K.O.]

My 1985 Daisy 953 (functionally the same as the 853 I linked to) is not very pellet picky at its intended use 10 meter target and when it was

shooting 7.9 grain pellets at 425 fps I picked up a tin of Crosman .177 10.3 Grain ultra magnums that the head size was even larger than


normal(and normally the are a bit large anyways) well guess what they got stuck at the choke and did not make it out of the barrel...

So did I need a statistical analysis to know with that power plant and that barrel with 100% certainty pellet head size mattered...

Now if I put a modern Daisy 953 barrel on it (faster twist less lands and grooves and no choke) that same pellet most likely made one hole groups at ten meters...

https://www.pyramydair.com/product/daisy-powerline-953-targetpro?m=585

Back in the 90's I did computer programing and my 23 year old Daughter is in the last semester of a Bachelors in Applied Math so I know enough to know you need to define your limits.

Without some very expensive equipment to analyze each barrel you can not set meaningful limits imo...

The Benchrest guys have advanced the powerplants and barrels and that minimizes the effect of headsize when done right.. but does not mean it is voodoo...

[K.O.]

A long time ago there was a barrel maker named Harry Pope that made some excellent barrels for the time he loaded from the muzzle for a reason...do you know why...

There is a very large interplay of variables that needs understood and that is just to get the projectile out of the barrel...


For me the fun is applying the knowledge I have gained over my 50+ years( and continue to gain) to make what I have perform at its best within my budget...

[JerryCup]

I dredged up this topic in searching for information on gaging pellet head sizes. Saw the Dan Brown air pressure system demonstrated online:


If you are interested in another measurement method, you might try a new product I have developed. It's a lot simpler. Don't know what the air flow system costs, but it has to be a lot - requires a compressor, too. See:
http://www.pelletgage.com

The Dan Brown gage was explained to me by a champion shooter who purchased a PelletGage.

There will soon be user reports on this, but prototype testing has all been very positive.

[StevenG]

A long time ago there was a barrel maker named Harry Pope that made some excellent barrels for the time he loaded from the muzzle for a reason...do you know why...

There is a very large interplay of variables that needs understood and that is just to get the projectile out of the barrel...


For me the fun is applying the knowledge I have gained over my 50+ years( and continue to gain) to make what I have perform at its best within my budget...

Can I take a guess? Muzzle is a tiny bit larger than breach and forcing the bullet down into the breech sized it.

I see pellet sizers were a thing and then not and back again. I wonder if they actually work.

[TCups]

The Cardew brothers classic book, The Airgun From Trigger To Target (out of print, can be downloaded here:  ) gives the analogy of blow guns vs. pop guns.  A BB in a smooth bore is a blow gun.  A pellet tightly seated in the breech of an air rifle is like a pop gun --  if you are of a certain age, you will remember the cork on a string in a toy gun that "popped" when the handle was squeezed.

With both springers and PCP's, firing the rifle results in a very rapid increase of pressure behind the pellet before the pellet pops loose and starts down the barrel.  The rate of pressure rise is extremely fast, not unlike the explosive pressure behind a bullet in a powder-burning cartridge.  A tighter fit of the pellet head results in a fractional delay, in milliseconds, before the pellet starts down the bore.  Although the total volume of air that eventually pushes the pellet out the barrel is pretty much the same, the near-instantaneous rise in the  absolute pressure level behind the pellet before it starts its journey, and therefore the initial acceleration and velocity of the projectile vary.  Head size affects the pressure that builds before the bullet starts, and the force controlling the projectiles initial acceleration and velocity.  It also effects the lock time, in the sense that tighter pellets take a bit longer to start their journey.  Variability in those factors means variability in the POI and accuracy.

As has been mentioned, skirt size is less critical -- but the careful shooter will find that pellets with softer skirts ( for example, JSB's, Vogels), which do easily squeeze to fit (and then expand under pressure and heat to fit the bore) are much more vulnerable to having the skirts dinged and deformed, degrading their accuracy.  Conversely, pellets with thicker, "stiffer" skirts (for example, Beeman FTS, Crossman Premiers) are less susceptible to having the skirts deformed by rough handling, but also less able to uniformly expand to fit the bore.  But while skirts affect the way the bullet travels down the barrel and pellet accuracy, it is the precise head size and fit that is the primary determinate of the initial pressure required to start the pellet in motion.

For those who reload powder burners for target shooting, you may quickly realize the similarity between pellet head size for air rifles and the variables of crimped bullets, vs un-crimped bullets, and seating depth / "jump" from the bullet's ogive to the lands of the bore for high power rifles.  Seating a bullet with no crimp touching the lands of a rifled barrel centers the bullet in the bore and results in a much more uniform (but potentially dangerously high) cartridge pressure. Seating deeper, away from the lands, lets the bullet get a running start at lower pressure -- a "jump" -- before it touches the lands.  But I digress . . . 

As for measuring pellet head diameters with calipers, it's like measuring bra size without knowing the cup size (at least that's a nice mental visual for me).  The diameter of the projectile at any opposite points on the head'd circumference can vary if the head isn't perfectly round, and calipers won't easily identify pellet heads that are out of round.  It won't always predict the "fit" of the pellet head in the bore.  The better way, by far, to measure uniformity of head size and roundness is with a very precise, perfectly round hole, to see how the pellet fits -- a "go/no go" gage.  That fortunately, is now possible and affordable, for much less than the cost of a decent set of calipers.  It is quicker and easier to use, and most importantly, gives a more accurate result.



This is available in .177, .20, .22, .25 and .30 calibers and perhaps others if demand warrants.

You can find out about the gages here http://pelletgage.com 

My initial testing says the gage is easier to use with domed pellets, but not hard to use on any type of pellet, and shows that even match-grade pellets sold by specific head sizes and lots vary significantly in weights and head size.  I now know this to be true, for example,  for Vogel's  in .177 in 4.58 mm, 4.59 mm, 5.00 mm, and for JSB Exact Heavy in 4.51 mm.  The manufacture's specified head size is readable on my older tins, before they started putting a UPC barcode over the orange sticker that had the Die #, Lot # and head size (mm) on the back of the tin. 

So, while I spent a lot of time sorting by weight, and tried, but gave up on caliper measurement of head size in the past, the availability of this new gage has renewed my interest in precision loading of my air rifles.  Extensive testing data is yet lacking, but my initial results, as well as those of  a few others, though "anecdotal" strongly seem to indicate using this type of gage will be a game changer for those serious about finding the true size and weight of pellets most accurate and most consistent in any given air rifle.

Check out the initial sort of this tin of Vogel 177's marked 4.50 mm:



4.51 mm     4.51 mm     4.52 mm     4.52 mm     4.53 mm     4.53 mm
 0.496 g       0.502 g       0.496 g       0.502 g       0.496 g       0.502 g
 0.498 g       -------         0.498 g       0.498 g       0.498 g       0.504 g     
 0.500 g       -------         0.500 g       -------         0.500 g       -------

Only 3 of the first 177 pellets were 4.50.  This tin sorts into 4.51mm, 4.52 mm and 4.53 mm sizes with most consistent weights of 0.496 g, 0.498 g, 0.500 g, 0.502 gr (7.65 gr - 7.78 gr).  Notice that the 4.51 mm pellet heads are grouping more at .498 g (first two columns of the box) and the 4.52 mm pellets are grouping more at 0.500 g (second two columns of the box), but that there is still a large overlap in pellet weight and head size.  Shooting pellets of matching head size and weight should help find the precise size and weight preferable for any particular target air rifle.  Careful range testing (bench rest, indoors, at 10 meters should be the best way) will follow when I have accumulated enough size/weight sorted pellets to do so, (and when the wife is out of the house) so I can set up an indoor 10 meter range down the hall with my Walther LGR-U immovably benched on a table in the bedroom and have a serious range test.



After sorting and inspecting, I am dividing the test pellets for the Vogels into two groups:  4.51 mm at 0.498 g (7.67 gr) and 4.52 mm at 0.500 g (7.72 gn)



I will post updates when I can.

tec





 

[K.O.]

A long time ago there was a barrel maker named Harry Pope that made some excellent barrels for the time he loaded from the muzzle for a reason...do you know why...

There is a very large interplay of variables that needs understood and that is just to get the projectile out of the barrel...


For me the fun is applying the knowledge I have gained over my 50+ years( and continue to gain) to make what I have perform at its best within my budget...

 



Can I take a guess? Muzzle is a tiny bit larger than breach and forcing the bullet down into the breech sized it.

I see pellet sizers were a thing and then not and back again. I wonder if they actually work.

Sorry I did not  see your guess sooner..

 And nope... from my reading up some of his barrels were gain twist and tapered from breech to muzzle... He Breech loaded the powder and then used a loading system to laod the round from the muzzle because it kept the base of the bullet in the best shape...


From:

THE OLD MASTER:

THE STORY OF HARRY POPE

By John Scofield, from The American Rifleman, June, 1941

"

“Will Hayes was another of the old-timers. The Pope muzzle-loading system mightnever have been developed if I hadn’t met him at the Newark Schuetzenfest in 1888. He was the real inventor of the ‘Pope’ muzzle-breech loading system. “Hays wanted a gun to load greased bullets from the muzzle, for accuracy, and yet use metal cases for convenience of loading. The rifle was made for him about 1884 by George Schalk.

Schalk didn’t want to make such a crazy gun, wouldn’t put his name on it, though after he saw it shoot he put it on in a hurry. It was a 16-pound ..33 caliber on a Ballard action, using .32-40 cases and a grooved 162-grain bullet with no patch. Hayes offered to lend it to me. Of course, I didn’t accept, but I did make one like it.

“I was still making barrels for myself alone. That first muzzle-breech loader I made was in 25 caliber, after seeing the results Hayes got with his Schalk rifle. Then I made two or three lighter rifles like it. The cases were made from .32 Extra Longs, and held 30 grains of powder with a 120-grain bullet.

“Not long after that I bought a heavy .32-40 Winchester Single-Shot and rebored it for a .33 muzzle-loader. With it I began to win. So far that rifle has been fired about 125,000 times, and all with the old mercuric chlorate primers. They’re supposed to raise *(&^ with a gun, but it’s perfect yet, after that use.

“It was at this time that I would save money to come to the New York matches from Hartford. Every time I’d go broke, have to borrow money for entry fees, then go home and borrow some more to pay my New York debts – that is, unless I’d been lucky and taken enough prize money to repay them, and then I’d be home again saving for the next trip.”

By this time the Pope muzzle-loading system was developed in its final form. Harry had modified the Schalk method of rifling as used in the original Hayes rifle: his own consisted of eight wide grooves on a radius about three times that of the bore, gain twist, with the corners of the grooves rounded instead of square, which tended to make cleaning easier. The grooves were cut just deeply enough to clear the bore in the center and give a depth at the corners of about .004 inch, half that of Schalk’s rifling. The lands were very narrow, about 1/8th to 1/10th the width of the grooves. The bore was given a slight, gradual taper from breech to muzzle.

To be capable of fine accuracy, Pope found that a bullet must be delivered from the muzzle with a perfectly square base. Breech-loading will not do this as fins of lead invariably are swedged out of the base of the bullet when it enters the construction of the bore nose first. To overcome this prime cause of inaccuracy the Pope bullet was inserted at the muzzle, the case with powder being afterward placed in the chamber in the ordinary way. By the simple act of pushing the bullet down the bore base first the dirt of the proceeding shot was scraped down the bore ahead of it, leaving a uniformly clean channel for the bullet when fired. As well, the base of the bullet remained square and concentric.

Each bullet had to be entered through a tapered false muzzle that gently swedged it into the bore without deforming it. The entire Pope system of muzzle-loading was developed to effect the delivery of a perfect bullet with its centers of weight and form true and undisturbed. By obtaining a phenomenal uniformity of delivery. Pope was able to secure the same uniformity in his results, reducing the error at the target to a minimum.

“Now look here. You say my muzzle-loaders took longer to load. Actually that isn’t so. The total loading time was the same as for an ordinary breech-loader. Just to show you: I was alone at the range one day, didn’t have to hurry, and noticed the time I took. In two hours and ten minutes I had fired 100 shots, which meant re- and decapping the shell, throwing a charge, lubricating, starting and seating each bullet as well as the normal procedure of firing offhand. You couldn’t load 100 cartridges with a modern loading tool and fire them carefully in much less time.

“Besides, loading between shots gives just enough time to get your breath back so that you are not blowing when you fire. Shooting too fast is hard to do with a muzzle-loader, so the advantage is with it there, too. Also, there are no cases to clean. We used only one case a day, and when we were through the thing to do was load it and fire it the next day for a blow-off shot.”

The superb accuracy of these rifles, properly handled, is unchallenged. Pope guaranteed that any of his muzzle loading rifles, with the exception of the 25 caliber, would shoot into 2 inches at 200 yadrs, loaded from the muzzle. Groups made by Pope, the late C. W. Rowland, dean of the old-time rest shooters, Donaldson, Roberts and others, that show ten shots at 100 yadrs and even 200 yards going into one ragged hole, have often been published. Pope himself has one 200 yard target that shows 10 shots grouping within 5/8 of an inch, center to center! Though temperamental, the Pope muzzle-breach loading Schuetzen rifle, under proper conditions and in the hands of a rifleman willing to study and master the methods that must be used to get results, will yet outshoot up to 200 yards any other type of rifle in existence.

"

[SpiralGroove]

I'll throw my 2 cents in here and assure everyone it will be worth every penny.

I pretty much do nothing but shoot competitive air rifle benchrest.  I do not know of a more particular bunch of guys.

I used to sort pellets by various methods.....rolling, optical comparator, and laser micrometer.  The last two methods were accurate to .0001 and beyond.  The first thing you notice with the laser mic or the 100x comparator is that there is no such thing as a truly round pellet.  About the best you can hope for with a tin of JSB's is .01mm out of round....with most being worse.  When taking roll sized pellets and double checking them on the laser mic.....I found that the out of round really screwed with the results that were being obtained.  For those that roll pellets.....simply squashing the skirt very slightly will make the pellet roll to a completely different place.  The circumference will stay the same.....but it rolls different.  I always pushed my pellets through a die to size the skirts consistently prior to rolling to combat this, but it really didn't work according to the laser mic or the comparator.

Long story short on rolling......the pellets that were classified by rolling were not actually the size graduations that I thought.  I tested them in their respective group sizes....and always seemed to find a particular group that shot the best.  I have no real explanation for that.  I quit rolling pellets when my friend beat me 2 matches in a row with pellets out of the tin.  He was too lazy to sort, and refused to do it. 

I then advanced to using the 100x comparator or the laser mic to take 2 position averages 90 degrees apart.  Still very time consuming.  I shot every sort size range individually and kept track of the results.  Then one day, I took the smallest pellets and combined them with the largest from the sort and shot some cards with those.  So these were the all the pellets that were grossly different than the majority on both ends of the scale.  Strangely enough.....I shot just as well over a 3 card average compared to any other size group I tried.

The sorting phase in my shooting history has been a lot more complicated than I care to write.....it would take a book to get it all down.  I have gone from ignorance to staunch belief to indifference over my time shooting benchrest.

I can give one particular case that casts great doubt on the entire head sorting thing for me.  I have a particular lot of JSB 8.44's that shoot averages of 250 18-20x indoors with an average head size of .1782".  They are fantastic pellets that would lead someone to the conclusion that my barrels like larger head sizes of 4.53 or so.  I also have another batch of JSB 8.44's that average exactly the same scores, but are .1770 in average head size.  I also have tons of other batches that are the same head sizes as these I mentioned......and every other size you can think of that come no where near the performance of the other two.  How does that compute if head size is what matters?

The above example tells me that head size may matter.....but it's certainly not the only thing that matters....and maybe its not nearly as significant as we thought.

I can also tell you that I have weighed pellets til the cows came home.....and could not find any conclusive evidence that weight sorted pellets improved my scores at all.  It should be noted that I only shoot JSB's or AA pellets.  Maybe weighing is beneficial for the more widely varying pellets like the crosmans. 

I quit sorting pellets completely last winter, and so have the other guys that shoot my bench rifles.....and still somehow we have managed to set 14 new national benchrest records in the past year.  All with pellets straight out of the tin. 

I have 55 yards indoors where I can shoot off a dedicated bench and a machine rest with a rifle that is extremely consistent.  Without those things, I think it would have been very, very difficult to arrive at the conclusion that I have. 

Right now.....I buy a tin of every batch of a particular pellet I can find.  I shoot a few cards with each one indoors.  If I find a great shooting tin, I order all I can of that particular lot.  That is the extent of my sorting these days. 

This has drastically simplified my shooting life.....but has not yet changed my performance.

Please know that I am in no way knocking anyone that finds benefit to pellet sorting.  If it works for them.....there is no reason to quit doing it.  I'm just sharing my personal experience in the matter.

Mike

I wish I would have read this before buying my pellet testing gauges .
I wondered why Mike was so anti-pellet sorting .... he already sorted, pellet sorting .
Now I know the back story ..............  .

[Bayman]

I wish I would have read this before buying my pellet testing gauges .
I wondered why Mike was so anti-pellet sorting .... he already sorted, pellet sorting .
Now I know the back story ..............  .

Thank you for reposting Mikes post. Besides making me feel better about being too lazy to sort pellets, it mirrors my personal experience that some tins inexplicably shoot better than others.

I have an old tin of JSB 8.44s that shoot better than any other pellet in almost all my 177 rifles. I saved the remnants for diagnosing rifles. My most recent sleeve of ten tins of the JSB 8.44 is very loose and doesn't shoot well in any of my rifles. The sleeve before that from a different lot shot markedly better but not as good the tin saved for testing. Also my last sleeve of JSB RS 7.33s is very loose and doesn't shoot as well as the last. I'm not sure if this is a degradation of quality at JSB or just bad luck. Fwiw I have had loose fitting bad shooting JSBs pre covid. It hurts to buy sleeves of pellets when finally available only to have them not shoot well. It does seem the very loose ones generally don't shoot as well as the snug ones. But not always.

I've learned to mark tins that shoot particularly well for the rifle they shoot well in and put them aside for hunting or diagnosis purposes. Generally even the worst JSBs are more consistent than Walmart pellets. Lately I've been getting more consistent quality and better results with H&N FTTs. Unfortunately they don't deliver the same energy as the JSBs but at least you can hit the target more reliably.

Be well
Ron

[BSJ]

Yep. I've got 4000 .22 Redesigned that I scrounged over last summer. They shoot like &^^&! I'm talking Sub MOA at 100 with the old to crazy random 7" fliers with the new!

H&N for everything now. Wish they made a 25gr ".22 Redesigned" equivalent that shoots as well as the JSBs used to...