Pellet head size

I feel head and skirt size is important regardless of caliber, but the larger calibers are less affected than smaller calibers for sure. Much of that has to do with the percentage of change in my opinion. A .002 change in diameter is a larger change for a .177 than a .22. That's over 1% change for a .177 and less than a percent for .22. By the time you get to .25, it is a smaller percentage yet.

I am sure there are other factors, but I size all of my pellets regardless of caliber because it is important for the best possible precision.

This is one subject that has been beat to death so many times, that only a small blood stain is left! While both head and skirt size is important as AJ points out, nonetheless it is amazing how well some pellets shoot irrespective to their varying diameters and lopsidedness. But seemingly, the one factor no one wants to address, is the shooter!

Besides my interest in varmint hunting over the years, in the late 60s I got interested in bench rest shooting. At the time, the state of the art was getting into the low ones, and almost no one did. I can remember the first time I broke .150! I was extremely elated. One of the gun club's better shooters made a statement to the effect, that anyone shooting in the twos, couldn't do better if they used his weapon, and that he could do better than they could, using theirs! Money was placed, and the contest began. It was no boast—He was right!

At 76 years of age (today, by the way is my b-day), I still have 20-10 distant vision (I use cheaters to read). Yet, I cannot shoot like I once did. I can't say if it is technique issue, pleurisy, arthritis, or lack of testosterone! But whatever it is, I still do my best to minimize the variables, as well we all should. I have a decent rifle, I buy the best of pellets, I use a really good rest, I breath as best I can, and I concentrate. If we all practiced these important points, we wouldn't be worried about the pretty heads and skirts!

Happy birthday!!

Removed content as I misread Alan's reply.

I say head size is only relevant if you have execellent shooting skills...if you can't shoot worth a $h!t the head size of the pellet won't matter. The same point Alan made.

I agree, Alan. Like you I have been around long enough to know that there is so much myth and marketing hype in the sport to make it difficult to identify fact from fiction.
Some of the newer high tech air guns may be influenced by pellet head size, but my old favourites certainly are not. A very happy birthday.

I shoot my break barrel alot more than my PCP. I can feel the way a pellet fits into the barrel. I know that if a pellet fits "loosely" that it is probably going to fly. Of course, with that thought, my aim is probably not going to be as careful and I give up on it. That may be psychological but I have developed that bad habit.
I have thought about trying to find some type of spring loaded, vacuum syringe gizmo to extract the pellet, but I don't know what I would do with the loose fitting pellet so I just shoot it anyway.

Whilst good barrels can be quite tolerant with a range of head sizes when shot in batches, even good barrels have their limits.
These two targets seem to indicate that if pellets are batched this barrel was happy enough with heads from 4.47 mm to 5.51 mm.
At 4.45 mm things are deteriorating; worse at 4.43 mm and at 4.41, well, shotgun pattern.
These were shot at 25 yards over a chair cushion with a .177 RAW TM 1000. Pellets were sized as indicated. All are 5 shot groups.





What the targets don't highlight is the slightly different points of impact each head size may print at if pellets were mixed for head size within groups.
Batching can help to reduce group sizes down to that for each head size. Sights can be adjusted to center any particular size on the POA.
My thoughts ... Regards, Harry.

Hi.
One thing i don't understand, if we have a choke and pentagonal crow barrel, constant velocity pellet every shot, a tin pellets no selected.
When we are shooting and the pellet passes through the chocke and pentagonal crown, it is recalibrated and everyone have same head, same skirt and same velocity. The only difference I see is the weight or gravity center ???
Regards Enkei

enkey ... Potential accuracy/precision can be affected long before the pellet reaches the choke.

The pellet's attitude as it is loaded into the barrel can be affected by its head and skirt size and relationship. This can and does lead to in-barrel yaw which may be magnified by the air blast. Then its attitude may be further altered as it hits the choke restriction.

Kris ... I'm not sure that your response was in relation to my targets or was just by way of general comment. So to clarify my targets:
All pellets in six of the groups had their heads re-sized as indicated. Three of those groups are as good as the "from tin" group. The one with the mixed 4.44/4.45 mm size is pretty close too (possibly the 4.44 size is to blame for the slight deterioration) and of course the other two groups with even smaller heads are sad.
I can down-size heads and/or skirts to any size I choose with seamless flexibility which allows for studies such as that one.
The commercial dies, that I do have, have not altered from wear over the last 20 years. As with our barrels, lead alone does not seem to wear the steel. ... Kind regards, Harry.

Allow me to interject.

One thing we need to remember (besides the ability of the shooter), is the fact that pellets are not an exacting manufacturing science—at least not yet! If they were, they would vary about the same as an equivalent powder rifle bullets. Obviously, they do not. 

I have never measured .177 caliber bullets, but I have measured .22 caliber, and .338 caliber ones. A .22 caliber is actually .224 inches in diameter. I have a digital caliper which can measure down to .00001 inches. The variance between bullet to bullet in any given batch, is LESS THAN .0001 inches. The weight variance (digital scale) of a Nosler .224 caliber, ballistic tip, varmint bullet varies less than .01 gains! The .338 Sierra measures just as close! There isn't a pellet manufacturer who even comes close! 

The fact remains, until manufacturers step up to bullet-type manufacturing accuracy, we all are going to be wanting! But.... If they do, be prepared to pay almost as much for pellets as powder burners do for bullets!

Alan, your point is perfect and also reiterates why sizing makes sense. Sizing is only a positive because of the poopty quality of pellets we buy!!

Can we assume from yrrah,s targets that 25% to 33% of the time the head size makes a difference and that 75% to 66%, the remainder is on the shooter's aim and other shooting skills?

Beach-gunnerCan we assume from yrrah,s targets that 25% to 33% of the time the head size makes a difference and that 75% to 66%, the remainder is on the shooter's aim and other shooting skills?

Click to expand...

I think you make a very good point. Remember those targets were shot at close range. I have never seen what I would consider meaningful impacts for my purposes until range is extended. We all have different skill sets and needs. That puts more or less emphasis on something like sizing or even sorting. For BR guys, any gain is a needed gain. For a close range plinker or hunter, it probably makes no difference. For myself, I will take any gain regardless of how small for what I consider to be my typical airgunning.

I can go with some barrels for whatever reason aren't overly picky on head size. Head size in my LW match barrel does make a measurable difference.

I sorted Crossman Premiers into groups by head size. Then fired each head size by group to see the difference. The gun was in a Lead Sled DFX rest with the scope set at max so the variation was pellets, not shooter. There was a relatively constant left to right breeze which I deliberately didn't compensate for, hence not on zero.

Take a look at the number of pellets per group and how the group patterned. The .5 446's sprayed into a 4+" group while the 11 .450's ripped a single hole. I'd attribute this to the .446's "banging around" loosely as they pass down the barrel and getting nicked up. if you mixed all these together (taking them straight from the tin), one would be blaming the shooter vs the difference in pellets.



My rifle has a clear preference for crossmans in .450 pellets. The .453's patterned well also but that isn't typical. But take a look at what it does with its favorite pellet (the Barracuda .451). That's 10 pellets into the same hole. So yea, in some barrels, head size and pellet configuration makes a big difference. 

Harry. Thank you for your answer. This topic is very interesting for me. Know how to interpret a grouping, I think it is very important for the advancement.

many thanks for this work and explanation

thank you

Thierry

Good info, sharroff. I agree with much stated above. Especially that too small a head (or skirt) size could result in pellet yaw in the bore. Yaw in the bore would not be good for accuracy and would probably produce much of the spiraling some people see. Conversely, too large a head size would probably not produce such yaw/spiraling effects once sized into the breech but probably would cause noticeable lead smearing along the pellet body upon loading which could effect resistance, velocity, and stability if some of that smeared lead falls off in barrel or on exit at the muzzle. Would this be more noticeable at longer ranges? Seems it would.

I have reloaded many .257 rifle bullets over the years (regularly shoot a .25-06) and as noted above variance among even acceptably accurate rifle bullets is lower than that for pellets. Seems even the very best pellets will generally have higher percent variance than most rifle bullets.

Personal opinions based on experiences with my .177 cal HW95 and .177 Beeman R9!

I believe that as long as the pellet head is large enough to be "sized" in the barrel leade there will be consistent accuracy because every pellet that passes through the smaller leade will be swaged to the exact same size and shape. That "consistent accuracy" will vary dependent on the geometry of the bore.

For example a couple of my .177 HW95 barrels there were a couple minor constrictions, one where the barrel was pressed into the barrel pivot block, one where the "numbers" were pressed into the barrel, and a tighter constriction at the "muzzle choke" These constrictions could be easily detected by carefully pushing a new CPL through the bore.

Anywhoo........I have a .177 Beeman R9 break barrel which has a rather loose leade that is very accurate when shooting 7.9 grain CPLs with their "largish" 4.54mm-4.55mm heads. With both the .177 R9 and the tight leade .177 HW95 the "fat headed CPLs" were/are very accurate, however loading a couple hundred CPLs into the HW95 during a shooting session WILL give me a "sore loading finger". I made up a pellet head sizer that gave me CPLs with 4.48mm heads and they were extremely accurate from the tight leade HW95, but not so much with the looser leade Beeman R9. I later found that when I opened up the pellet head sizer to give 4.50mm CPL heads the pellets were accurate with both the "looser leade" R9 and "tighter leade" HW95 without the sore finger syndrome. Playing with cheap Winchester Domes I bought at Tractor Supply (black & gold label) I found that the pellet heads were rather small.........

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When shot at only 18 yards those cheap pellets weren't very accurate from the .177 "larger leade R9", however they were pretty accurate at 18 yards from my "tighter leade HW95 (shot sitting on a "bucket" resting the gun on cross sticks).............







LOL....each group had one flier. Humm....bad pellet or bad shooter? I vote for the SHOOTER!

I recently bought a few tins of 4.52mm AirArms domes and found that most of the heads measured 4.51mm.........



so I shot a group "straight from the tin", then ran some AA domes through my 4.50mm sizer and shot another group, again at only 18 yards sitting on a bucket resting the gun on cross sticks. The sized AA dome group was a bit tighter than the "straight from the tin group", however that simply could have been "shooter related" rather than pellet head size related............





Anywhoo....as mentioned previously, I believe that as long as the selected pellet has a head large enough to be "swaged when loading", every pellet going down the bore will be the exact same size and shape. The issue is when the pellet heads vary so much that some are "swaged at loading" and some are so loose fitting in the lead that they rattle down the bore! This is the issue I had with the supposedly 4.52mm JSB Exacts I bought a couple years ago. All were a bit undersized, however some had heads so small and loose fitting that the pellet would flip out of the leade simply when relatching the R9 barrel! That episode years ago prompted me to measure a few thousand supposedly 4.52mm JSB Exact pellet heads and this was the result............







At that time I also had a tin of supposedly 4.50mm JSB Exacts and found pellets in the 4.50mm tin with heads larger than many from the 4.52mm tin and visa-versa!