Pellet sizes, 4.50, 4.51, 4.52 and so on.

What are the different head sizes all about?

Hello to all, I’m not so new on this forum, and not new to airgun forums as I’m a participating member of our local forum in sunny South Africa and would like to introduce myself. My real name is Johan Swanepoel and my friend that helped in this research is Dale Sullivan. I’m an ex analytical chemist and Dale, well he had to do with guns his whole life and is the biggest walking, talking encyclopaedia on WWII rifles, airplane and history, that I’ve ever met.

Our research on pellet head sizes has proven to be somewhat entertaining.
What are you actually getting when you buy a tin of pellets claimed to be 4.51, 4.52 or so on.
We bought a tin of JSB Exact (4.53) and a tin of FX Premium (4.52)

Setting the micrometer to the claimed pellet diameter, we simply observed which pellets heads passed through the set gap. We didn’t use the micrometer’s ratchet for fear of deforming the pellet.

Here are the results of our measuring:

JSB Exact (4.53 mm) Sample of 10 pellets.

Set at 4.53 all 10 were smaller.
Set at 4.52;    9 were smaller.
Set at 4.51;   6 were smaller.
Set at 4.50;   3 were still smaller.

FX Premium (4.52 mm) Sample of 10 pellets.

Set at 4.52 all 10 were smaller.
Set at 4.51;   9 were smaller.
Set at 4.50;   3 were smaller.

The pellets that passed through the set gap without touching the jaws were turned a quarter of a turn at a time to see if they weren’t perhaps oval, but they did not measure to the set size.
We were told by e-mail from H&N that one can’t measure the head size of a pellet with a micrometer, but only with a so called ‘ring gauge’. That’s why went to the stage where we only observed pellets passing through the set gap without touching.
This is just an example of quite extensive research and we are only putting the question, what is the point of quoting a size that simply is not true.
We are by no means commenting on the accuracy of the pellets, just the fact giving such figures seems to be rather pointless.
Are people thinking they are buying oversize pellets, if so the tables above show a slightly different story?
We have found similar discrepancies with pellet weights, what’s written on the tin and the actual weights are often rather different, again we know consistency is most important thing, but simply what is the point of quoting wrong figures.

We have asked JSB to comment on our findings, so far without any reaction or reply.

Kind Regards
Swannie and Dale Sullivan

PS. We were told from all sources, starting with H&N, that it is the head size that is measured and not the skirts. We also started of by measuring skirts and know them to be far bigger.
Chrony results also indicated that weight instead of head size were the determination factor, as the lighter pellets were the faster and not the one with the so called bigger head diameters.

[-=ed]

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. < s i g h h h h>

More truth in advertising...

I use 4.52 Daystate FT [jsb exacts] weigh them, and combine the largest piles until I get 90+% of the pellets, usually the 2 middle ones, and use them for targets.

I use the rest for shooting at paint balls and toy soldiers and chalk.

When I get good enough, I may get a sleeve, and spend some time sorting them and keeping the different weights seperate... nahhh, too much work, but maybe I can get my wife to do it... :p :p

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[Gene_SC]

Great question Johan and Dale

I am no expert on pellets and have not done the micrometer tests. But if the size difference is advertized the same as weight's then I am not surprized at your findings.

I bet if JSB contacts you that you will get the same jibberish from them as well.. I wonder if there is a pellet out there that weighs and is sized as advertized by a manufacturer?

Thanks for the post Johan and Dale

Gene

[daved]

Hey, Johan,

Nice write up, and some nice research there.  So now that I've been nice, I'm gonna disagree with you :-).  Actually, the only thing I take exception to is your PS regarding chrony results.  Awhile back, I ordered a mixed sleeve of JSB Exacts, head diameters from 4.50 to 4.53.  With a freshly tuned Gamo CFX and a brand new Chrony Beta, I proceeded to test both velocity and accuracy.  The one thing I don't have is a scale, so I can't weigh my pellets.  But JSB's have a history for being very consistent in that regard.  So with the assumption that the weights were as advertised, I found significant differences in both velocity and accuracy, with that gun.  For whatever reason, the 4.52 was the best in all categories, accuracy, velocity, and deviation.  4.53 were slightly slower, the 4.50 and 4.51 were MUCH slower, and accuracy was, well, shotgun pattern rather than groups.  Don't have the data in front of me, but as I recall, the 4.52's averaged around 860 fps, with maybe a 5 fps extreme spread.  The 4.50's dropped over 100 fps, and like I already said, forget hitting what you were shooting at.

Interesting current note.  The gun used above has recently been converted to a gas ram.  And now it flings 4.52 Exacts all over the place.  The 4.50 JSB Match Diabolo S100 is my current control, on my 10 yard indoor range, that pellet will consistently group 5 shots inside a 1/4" bull.  The Exact 4.52 used to be almost as good, now it opens up to almost an inch at 10 yards!  The really weird thing is that the 4.51 and 4.53 now group slightly over 1/4".  Haven't tried the 4.50's yet.  Nor have I chronied any of them recently, but will be soon.  Just thought I pass along my experience.

Dave

Hello Dave,

Thank you for your reply.
I sort of expected this reaction from you as I have read your post before I posted mine.

I must also say that I thought your research was very well carried out, except for the fact that you did not weigh your pellets and that you assumed the head sizes to be what were quoted.

From the measured head sizes you can see that both are barely anything else but 4.5 mm.

My problem was that I could not get hold of different pellets head sizes of the same make and had to do with two makes.  Both has weights quoted as being 8.44 grain ( FX Premium quoted weight on the tin and JSB Exact only quote there sizes on the Web), but by weighing them I found the FX Premiums (4.52 mm) to be 8.40 grain and the JSB Exact (4.53 mm) to be 8.44 grain. I’m using a four decimal place analytical balance weighing in gram (0.0001gram).

As I understand it, a heck of allot of pellets are nowadays been manufactured at the same plant such as JSB and if you look at the FX Premiums and the JSB Exacts they look almost identical.

The difference in velocity was a mere 11 fps, with the lighter being the faster. I also shoot strings of ten pellets. I’m shooting with a CZ200S with a Hawk Airmax 4-12 X44 scope on. The CZ200S is exactly the same as the AA S200S that you might know in America. Before each string I pump the rifle to exactly 150 Bar.
 

I bought my F1 Chrony just before I bought the micrometer, both in December 2006.

I will extend my research as soon as I can get hold of more different head sizes from JSB and will let you know my findings.

Dave said: "Interesting current note. The gun used above has recently been converted to a gas ram. And now it flings 4.52 Exacts all over the place. The 4.50 JSB Match Diabolo S100 is my current control, on my 10 yard indoor range, that pellet will consistently group 5 shots inside a 1/4" bull. The Exact 4.52 used to be almost as good, now it opens up to almost an inch at 10 yards! The really weird thing is that the 4.51 and 4.53 now group slightly over 1/4". Haven't tried the 4.50's yet. Nor have I chronied any of them recently, but will be soon. Just thought I pass along my experience."


Reply:

Hello Dave,

I wanted to remark on this as well, but being in my own little world, have cleanly forgotten about it?

So you haven’t chronied the pellets after the conversion to gas ram, and have no idea whether the velocities are higher or lower. Probably higher, I would presume but definitely more constant.

I dearly hope you get some means of weighing your pellets as this is truly set for a nice research project.

Swannie

GeneSC

Thank you Gene for your kind words, we do appreciate it.

To tell you the honest truth: this is the first Forum that would sort of listen to what we are saying. All the rest argues the point that you can’t measure pellets the way we do. I can’t see the point of, if a pellet passes through a micrometer set gap without touching the jaws, how can it be bigger than the set gap.

The fact that JSB has ignored our question is also a little worrisome, as we would gladly be proven wrong in our measuring ways. As a friend of mine said, he doesn’t want a pair of number 9 shoes, if he bought a pair of number 10’s. On the other hand you could say: if the fit, why worries? My point is: why quote the wrong figures?

Kind Regards
Swannie and Dale

[daved]

Actually, I have done some chrony testing post-conversion, but of various pellets, not the dedicated test of just JSB Exacts in different head sizes.  I wasn't totally accurate, I have tested the 4.52's, but none of the others.  And yes, they are shooting a little faster (<10 fps diff), but not quite as consistent.  But I've made another change since that test, a new piston seal, and have done NO testing since then.  Trying to shoot in the new seal.  Had already planned on doing some testing this weekend.

I agree, this is turning into a nice research project.  I have some friends that are powder gunners and reloaders, I think I need to see if I can borrow a scale.  Won't be as accurate as what you're using, but 1/10th grain should be good enough for our purposes here.  Although I could also measure head diameters, I recently bought a digital caliper, I'm not sure my nerves or my eyes could handle it :-).  But I'll probably try at least a few using your methodology, just to see if I get similar results.

BTW, went back and looked at my JSB post.  Obviously, my variation wasn't as great as I recalled.  Glad it was still there, looks like I deleted all that data from my computer.  Damned if I know why, that's ususally the sort of info I like to hang onto.  Guess that's all for now, but check back Sunday evening.  This should be interesting.

Dave

[daved]

Still haven't scared up a scale, but decided to measure a bunch of pellets today.  And yes, the eyes and nerves both survived :-).

First, I changed the methodology from what you did.  I went with a set gap, but was interested in a pass/fail only.  So for the 4.50's, I set the gap at 4.49.  With the pellet sitting on my desk head up, I slipped the caliper under the head at the waist, and lifted.  If it passed through, reorient 90 degrees, and try again.  If I lifted it off my desk with the calipers, it passed, if not, it failed.  I didn't bother to retest the failed pellets to see what they actually measured, all I was interested in was getting a group of consistent size in each head size.  That's the first cut.  When I come up with a scale, weight will be the second cut.  Not sure when that will happen, this may have to go on hold until I can order a scale.

Here's the new data.  An interesting trend arose as I was measureing the pellets.  As the nominal head size increased, the incidence of undersize pellets also increased.  I'm going to use the Match Diabolo S100's as a control, so I measured a bunch of them also.  What I have a 4.50's.  Both these and the 4.50 Exacts were very good, I didn't actually count, but I'd say only 10% failed.  The next step, 4.51, jumped to something like 25% failed.  4.52 was over 50%, and the 4.53's were terrible, around 90% were undersized.  I also think I had at least one tin that was mis-marked, the open tin of 4.52's I started with had a near 100% failure rate.  I opened a new tin, and got the previous listed result.  I'm still not certain about the measureing method, but regardless, I think it's pretty apparent that JSB's quality control is slipping.

Guess that's it for now.  I still have one more possible source for a scale tomorrow, but if that doesn't pan out, I'm definitely waiting until I can get one.  Do you think 1/10th gr. resolution is going to be good enough?  I'll look for better, but cost is certainly a factor.  Later.

Dave

Dave,

Thank you for taking the time to also measure the pellets.

It seems as if JSB is only making one head size but are marketing it as different head sizes, hahaha.

The problem with a balance that can only read 1/10 grain is that you wont be able to tell the difference between a 8.40 and a 8.44 pellet and  I have found already flies at different speeds.

Best Regards
Swannie

[daved]

I'd already come to the same conclusion.  The JSB Match pellets are listed as 8.26 gr.  So far, the best I've found that I can justify buying ( got a wife, ya know :-)!) will measure to .05 gr.  Slightly more expensive, and I get .02 gr.  From that point, the price takes a big jump, too big for my budget at this point.  Still trying to come up with other options.  Since I invested the time in measureing, I want to hold off 'til I can figure out how to get .01 gr. weight resolution.  Will keep you posted.

Dave

[-=ed]

where did you see the .05 and .02 grain scales?

They might suite my purpose.

[daved]

You're in luck, ed, I just happened to bookmark several sites, so here's some links:

http://www.scalesgalore.com/acculab_vicon_scales.htm
http://saveonscales.com/product_gempro150_digital_scale.html
http://www.rightonscales.com/web/gempro.htm
http://www.toplinedigitalscales.com/catalog.php?action=124&item_id=397

It's amazing, go from 1 mg. to .1 mg. resolution, and the price jumps 10 fold, at least.  It's looking like I'm going to have to settle for .02 resolution.  HTH.

Dave

As from one of Mother Earth’s most beautiful sons, you have got to listen at this bit I want to tell you:

When asked a question, please listen before you answer. When asked a question, make sure you know what the question is before answering.

Please don’t do as the English does:  http://www.airgunbbs.com/forums/showthread.php?t=168404

Kindest Regards
Swannie

[daved]

I'm not comfortable with writing it all off to sales hype, especially as there is no difference in cost between the different sizes.  Swannies' initial question intrigued me enough to pursue this, but I have a personal bottom line, and this is it.  The different size pellets shoot differently in my gun.  It's that simple.  Based on the results I've gotten so far, I don't know why that is, but the numbers don't lie, or at least my Chrony doesn't.  I now have carefully size screened batches in all 4 head sizes, plus a control.  Now I just need a good scale to screen for weight.

I might have confused the original issue.  Swannie wanted to know why the manufacturers were claiming something that didn't seem to be real, i.e. different head sizes that really aren't.  His measuring and mine both show a similar result, which doesn't agree with the manuf. claims.  Thus his question, why bother?  What got me going was his assertion that the only differene was in pellet weight.  I've tested all four, and got very different chrony numbers.  But I never checked for size or weight.  So now I will.  Does it really matter?  Probably not.  It's really just an intellectual exercise for me.  But it's fun, and the results should be interesting, at least.  But as long as my gun shoot x-size pellet better than y, I'll keep buying x, whatever that may be.  Besides, it's just another excuse to mess around with my air guns, who's gonna argue with that ;-)!

Dave