Why do pellet weights vary?

by B.B. Pelletier

I’m writing this post for myself, as well as for the customer reps at Pyramyd Air. The situation is this…Pyramyd may list a certain pellet with a weight of 7.5 grains; but, when the customer receives his, they weigh 7.3 grains. Or. I may write a post in which I use a certain pellet that I say weighs 6.9 grains, but Pyramyd is listing it at 7.0 grains. Readers see these disconnects and wonder if anything they read is correct. Why should the weight of lead pellets vary?

Not talking about tolerances
Everyone knows that there will be small weight variations from pellet to pellet in the same tin. That is not the issue I’m addressing. I am talking about when the average weight of a certain pellet does not agree with the listed weight on the site or with the weight I have written in a posting. Why should pellet weights – the weight the company publishes – vary?

The business of making pellets
Pellets are made on automated machinery that runs constantly and turns out thousands of pellets each hour. In the larger companies (e.g., Gamo, H&H and Crosman), there are batteries of these machines turning out several million pellets every day. If you look at the types of pellets a company makes, and that includes different calibers within the same type, you’ll soon see the number is very large. No company can afford to run machines to make every type and caliber of pellet they produce all the time, so these machines are scheduled to make different pellets to keep up with the demand.

Lead slugs
The pellet-making machines are fed lead slugs that weigh a little more than the final pellet. These slugs are usually cut from lead wire that is wound on large spools and fed into a cutting machine (large companies have many machines).

Pellets are formed by precision dies
A multi-piece steel die forms the lead slug into the pellet by either mechanical or hydraulic force. The pellet-making machine operates this die set, forming the pellet and removing the excess lead, called a sprue, after the pellet is made. In a large company, there are dozens or even hundreds of dies, all are either working in pellet-making machines or in storage awaiting their turn in the machine.

Production runs
Let’s say a pellet company sells 50 million of pellet “B” every three weeks. It takes them four days to make that number; so, when they reach 50 million, they stop making pellet “B” and switch over to pellet “C.” In another couple of weeks, it’s time to start up the pellet “B” line again, so the dies are installed in all the machines. They’re run and adjusted until the weights are as close to the nominal weight as they can get them. Because these machines are adjusted with each new run, they are not able to make the exact pellet weight of the new pellet until they have been adjusted and run for some time. Every time they get a new shipment of lead wire, they have to check the output of the machines to ensure they still make pellets of the same weight. If the metal supplier sent wire with a slightly different lead alloy, it will produce pellets of a different weight. Sometimes, that can be controlled…and sometimes, it can’t.

Naturally, the company tries to smooth out the production cycle as much as they can, so there won’t be any variation whatsoever, but you have to realize that it’s also nearly impossible to control. Whenever anything changes – new pellet-forming dies, a new pellet-making machine, a fresh lot of lead wire, major maintenance to a pellet machine or anything else, the weight of the pellet can change.

There’s a good analogy in reloading
Reloaders know that a turret-type reloading press with multiple functions will deliver good results, but not so good that there are no variances every time the press is run. The ammunition they make is often as good as factory ammo, but it’s hard to make it any better with a fully automated reloading station. That’s why benchrest shooters load at a single-station press and hand-weigh every powder charge and every bullet they load. They are like the JSB factory or the H&N factory making match-grade pellets.

If you have a real need for uniform pellets, do what the 10-meter shooters do. Buy your pellets 30,000 at a time and get all the same lot number. But, if all you want to do is have some fun shooting, you need to know that pellet weights are sometimes going to vary from the published numbers.

15 thoughts on “Why do pellet weights vary?”

  1. I just saw that Gamo Hog hunting video. I was looking at the free hunting shows on Pay-Per-View and saw it. First the show, Featured on OLN, starts off with 45 yard praire dog airgun hunting. The praire dogs are shot dead, but a closer look reveals that they are only crippled.
    Next was the Feral hog hunt. Dogs cornner the hogs (which is common practice) and he walks up with a Gamo rifle. He is shooting a 1600 fps rifle with pba ammo. He puts 1 shot into the head. It makes me sick. It instantly killed the hog but 1 inch right or left, the hog would just run off. The PBA ammo even pentrated a 2×4. Is that PBA ammo made of steel. It’s like amor piercing ammo.
    This might seem impressive, but just because you can, doen’t mean you should. You could use a screw driver to hunt if you were that sadistic.

    If any one wants to know the show so they won’t watch it, it’s Steve Scott’s hunting adventures. By the way, there was a gamo rep present.


    Please e-mail or write Gamo and OLN to get this madness stoped.

  2. RWS puts the weight right on the lid of their pellet cans and it is correct. I measured 10 of each pellet out of every tin with very little variation. I think out of the pellets I own the Gamo are the worst for variation. I’ve found a few that were nothing more than just a skirt with the head missing. I’ve seen the Gamo match wadcutters advertised at 7.5 gr and most of the tin weights in at 7.7 gr. The Gamo hunter domed were supposed to weigh 8.3 gr and ended up weighing 7.4 gr. You can get scales that weigh to a 1/10 of a grain for about 30 bucks or so anywhere on the net. They are quite helpful.

  3. Hey B.B.,

    Are you a mind reader too?

    Over the last week or so… time permitting… I’ve been hand sorting a new box of .177 Crosman Premier 7.9 grn pellets. I had to buy some after reading your Blog. Got some JSB Diablo Exact on back order, too.

    After sorting about 400 pellets the individual pellets are ranging from 7.9 to 8.3 grn for an average, so far, of 8.0 grn.

    My $80 digital reloading scale claims an accuracy of “0.05% of applied load” so go figure. A topline scale might very well give me a 7.9 grn average.

    I haven’t found a single un-usable pellet yet… no ‘pee wees’ or mashed skirts. The blems I’ve set aside are really just because I’m being ridiculously pickey.

    I’ve found a very, very few pellets with thin spots in the skirt. Most of the blems I’m setting aside are due to small to medium scars on the dome. They’re scars like could be made by pressing a fingernail into the head.

    I’m going to stop sorting these when a get 500 ‘premium’ Premier pellets. If I see significant differences in accuracy between sorted ones and random picks from the box I may sort some more. Right now I’m guessing I won’t need to do that.

    However, sometimes I wonder about the Zen of airgunning. That whole, “Be the pellet” sort of thing. If pellet sorting is part of that it may be worth the effort, eh?

    Thanks for the pellet recommendation. I can’t wait to see how these pellets shoot.


  4. !!!!! sweeeeet., missed that one…

    @#&!, now that cash from the Career is GONE!!

    too bad they don’T do a .177 that could get a few more shots out of that little tank.

    BB. add me to the list of people wanting to hear what you think of those

  5. Okay, okay!

    I will review the Evanix AR6 pistol. I have to tell you now that the results Pyramyd gives look correct to me. And Turtle, you would get fewer shots from a .177 than a .22. Sounds counter-intuitive, but .22 gets more from a gun than .177.


  6. man, I havn’t had a case of “want-that-gun” for a bit.

    I got it bad for that piece.

    don’t know If you remember a while back I was looking into a pistol for squirreling, BB. We went back and forth about the P1 and that LONG magnum Daina (G5 i think). But, this is really what I was going for.

    Very much looking forward to when you get a chance to squeeze a few off and let us know your thoughts.

  7. turtle,

    I can tell ytou right now – it has rifle accuracy, but the air supply is limited. I have tested the AR6 before several times and that’s how it always goes.

    Here is the deal, you get the accuracy of a Falcon pistol for 2/3 the price. But instead of 15 shots at 12 foot-pounds, you start with shot one at 30 foot pounds and drop to 11 by shot ten.


  8. You have stated that the desity of the CO2 increases with a decrease in temp. Normally true, but not here volume is constant, the density will not change, only pressure.

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