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JSB heavy diabolo head size

I don't think you can trust calipers. I have a darn nice set ($200) and even they routinely give me deflated results because they simply are not designed for measuring tiny pieces of soft lead. There is a good chance that your calipers are either slightly off-center, or that they are pushing every so slightly into the thin edges of the soft lead.
 
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I use a air comparitor, it uses compressed air to measure pellet head sizes. It measures the pellet by the amount of air that passes around the pellet. The system which installs to a reloading press has a regulator and dies for the press. Ted has seen the the system at the Extreme Bench Rest in Tucson this past November which is made by a gentlemen named Mark Buchanan. He can make a system for 177, 22, and I think larger but not sure of that. If you would like his number just E-mail me and I can give it to you.
 
I have taken tweezers and put the pellets in my barrel not sure if it does matter but I had 3 jams in a row from gamo whisper pellets 150 the gamousa is saying 18.xx plus s & h and 22 found too big using my method (not actually a measurement) 4 of which were 12gr compared to the listed 10.4 but my scale only goes to the tenths 1.0gn? My word of advice.
 
"Arbull"I shoot jsb 22 cal 18.13 grain pellets, where does it say on the tin the head size, are different head sizes special order or something? Sorry I'm new to all this air gun stuff.
The information is on the back of he tin. If you order from Pyramid Air, the back is likely to look like the tin on the right

But if you order from places like Precision Airguns, or Airguns of Airizona, the tin will look kike the tin on the left with the sticker. On that sticker, it tells the head size, when it was made, what batch it was etc...
The head size on JSB"s range from 5.50-5.54....Most of the time it is 5.52
They have the different sizes to accommodate the different size diameters of the barrel's of the rifle.
Some sizes shoot better than others which can only be learned through experimentation. 
If you already happy with the performance you're getting right now....then no need to change 
 
Arbul, it depends on where you buy them from. Some retailers such as AOA, sell tins with a grocery store label showing the the head size on the bottom of the tin (see tin on left below). Then there are tins with a bar code and head size which is rare (see tin on right below). Most tins, including those sold by Pyramyd, have the sitcker shown on the right tine but don't show head size. More than likely, these tins have pellets with the standard 5.52mm head size.



For what it's worth, 5.52mm is the most common head size for .22 cal JSB pellets. The exception being the Jumbo Monster which have a 5.50mm head size. The only place I know that sells the Jumbo and Jumbo Heavy in different head sizes is AOA.

Scott





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"travels4fun"
For what it's worth, 5.52mm is the most common head size for .22 cal JSB pellets. The exception being the Jumbo Monster which have a 5.50mm head size. The only place I know that sells the Jumbo and Jumbo Heavy in different head sizes is AOA.

Scott





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Scott
The Monster are not the exception, you just got a tin of the 5.50 heads. They do come in 5.52...I own some. Talk to Bori at topgun airguns...he orders direct from JSB and imports it in. http://www.topgun-airguns.com
Mike
 
"SRGTO04"I use a air comparitor, it uses compressed air to measure pellet head sizes. It measures the pellet by the amount of air that passes around the pellet. The system which installs to a reloading press has a regulator and dies for the press. Ted has seen the the system at the Extreme Bench Rest in Tucson this past November which is made by a gentlemen named Mark Buchanan. He can make a system for 177, 22, and I think larger but not sure of that. If you would like his number just E-mail me and I can give it to you.
You may want to go with the air sizing gauge made by Dan Brown. He Came out with the original design, which is far more accurate, though a bit more expensive.