"Pellet" diameter question

I would say most have i know i have . When i find a 4.50 pellet that my gun likes and it comes in 4.51 4.52 i will try all sizes and even weights of the same pellet . If i can get in 8.2 and 8.4 weight , mine likes the 8.4 4.52 the best

I have checked head size on literally thousands of pellets and slugs in 177, 22, and 25 cal. and have rarely found any that are true to the size indicated on the tin. For instance, the JSB 34 grain MKII pellets range from 6.37mm to 6.39mm yet tin says 6.35mm. So if you say your gun likes X size pellets, exactly what head size are those? Do you know for sure? And we're talking head size here, not skirt size.

MikeVV said:

Have any of you attempted an accuracy check (a locked down gun is the best for checking) with the same (no matter the brand) weight pellet, but with the small diameter differences ?

Mike

Click to expand...

I have done some testing of .22 head sizes and found what head sizes are the most accurate in my rifles, regardless of brand and weight. There is a direct correlation IME.

I did some testing with .177 pellets (CPHP, H&N ftt, Air Arms Diabolo) and found it (sorting for head size) did make a difference in the AA and CPHP pellets. The H&N were most consistently sized and made the least difference.

I sort and weigh pellets i compete with . the batch i compete with ALL weigh the same and head size is the same . This means if i weight a tin and need 100 pellets for a competition all the pellets weigh exactly the same and head size is exactly the same but it could be 4.50 & 8.43g or 4.52 & 8.39 as long as ALL are the same for that competition .

rsfrid said:

So if you say your gun likes X size pellets, exactly what head size are those? Do you know for sure?

Click to expand...

In all due respect, Ross' comment makes some sense. There are some tins / brands of pellets that I have measured that mostly have a pretty tight range of +-1 head size so if the shooter happens upon one of those tins then it makes sense to (unknowingly) say that my gun likes X brand, weight and head size (printed on the can) of pellets. They continue to feed those particular "brand, weight and printed head size" pellets to their rifle and a lot or two down the road their accuracy goes haywire. Why, because those +-1 tins are pretty rare to find and the manufacturer's QC isn't consistent enough to meet the specs on the can. Consistently providing the shooter what's printed on the can costs money, time, resources and equipment maintenance all of which drive costs up and can't account for residual wear in the dies and variation in the process.

Even though one large manufacturer (JSB) makes the majority of pellets that many of us tend to shoot and re-brands those pellets, all are not created equal. Air Arms for instance has JSB make their pellets on proprietary dies owned by AA so their pellets are NOT the same as the average JSB pellets. The range of head sizes are generally much tighter than JSBs. I have also found that certain models of FX (re-branded JSB pellets) have had much tighter head size range than JSB. Therefore, it seems logical that FX may have theirs made on proprietary dies too but that is not fact only a non-SWAG.

The Wally World CPHP's have the widest range of head sizes that I have measured. Some of us plink with those pellets and they work fine for rolling tin cans but try to shoot tiny groups at 25Y-50Y with out of the tin pellets and you will see many fliers and groups that are not on par with other higher quality mass produced pellets. I have sorted many tins of CPHPs to cull out the head sizes that my guns prefer and it makes a huge difference when shooting for precision and accuracy.

I tried to measure head sizes with precision mics and it simply won't work. Yes, you may have the best mic on the planet but its useless because pellet heads are not round and you will chase your tail and give up on head sizing because your measurement system can't work like a PelletGage can. Once you find the head size that your gun likes you can rapidly sort pellets by purchasing a pair of Go-No-Go PelletGage Rs.

Here's a thought to consider ... I have often wondered if the choke in the end of pellet barrels was there to account for a wide range of mass produced pellet head sizes because a smaller choke effectively re-sizes those wide ranges down to a smaller size? I am no gun smith or firearms engineer but its crossed my mind more than once that chokes have a specific purpose to do that vary thing. But what about the unchoked barrels? Well they shoot just fine if you find the head size that they like. What do you think the slug manufacturers are offering so many different head sizes? Try shooting a tin of pellets that has a WIDE variation of head sizes like CPHPs through one of those unchoked barrels and watch your groups go crazy, LOL. You will have much improved accuracy with those pellets in a choked barrel.

I'm certainly no expert but I have learned quite a bit over the last few years shooting air guns. Some through reading internet resources like this one and some through seat of the pants experience. Respectfully I put more faith in the latter.

Hope all of my rambling makes some sense?

So ? are you suggesting we measure the pellet size after pushing thru the choke to determine what we buy ? interesting experiment ?

Certainly there should be a fair amount of technical proof as to the different head sizes offered by "whatever" manufacturer offering them, or they wouldn't be offering them.
My experiences have always been more of a "logical" theory... that if I use a larger head size (which I usually do) I'll get a slightly better seal inside the lands/grooves and possibly a slightly higher velocity,, however slight that may be,, which may or may not result to a more accurate shot.

I think the offering of different head sizes is because some guns chambers are either tight or loose fitting , a poster the other day said his gun lets the pellet fall out if he positioned the gun pointing up when loading . they offer head sizes for the fit ?

The availability of different head sizes is useful mostly to the extent it increases the number of unique dies that one can experiment with to find a batch his gun likes.

I have found no evidence that any barrel has an affinity for a specific head size down to the hundredth of a mm. Same gun, one tin measuring 5.48mm consistently and another measuring 5.52mm consistently...they group the same. And then different batches of the same make and model pellet measuring the same don’t group worth a damn.

I've measured the head diameter on various JSB pellets, back when it was displayed on the tin. I found the designation to be only generally accurate, not totally consistent. I think the JSB/Air Arms pellets might still show the diameter, not sure. And yes, the grove diameter in the choke should be a critical indicator. But frankly, unless one is involved in some very high level BR competition, I don't think sorting by head size is worth the time.

I have 3 rifles that were designed and tuned to shoot .22 MRDs and those guns are less picky because the ammo is a lot more consistent. When I am just practicing then I shoot from the tin but when I am shooting for record then I use sorted pellets. I have 2 other guns that I shoot 18 grain .22s and it’s in those guns that benefit the most from pellet sorting because there is more inconsistencies in the available ammo. If I’m plinking it’s not a big deal what I feed them but I tend to be more OCD and accuracy driven to shoot paper and hunting pests and that is when I am more concerned about the consistency of the ammo I use.