Weight Vs Shape

[Rez 4,961]

Having looked at a few posts. A thought came to me.. Mainly about pellets and a post made by Gaoler.

 

Is it the pellets shape that a rifle might prefer or indeed it's weight? Bit of both... Shape means accuracy surely, weight me proficiency... Maybe.

 

All my current rifles like fields, 4.52 in fact or 5.52 in .22. It's a simple design of the Diablo pellet, it's soft, the rifling grips the form well, thus banging it out the muzzle in the right way. It's a example of a great design indeed. Same with Exacts.

 

Why do other pellets work better? I know it's a tuffy to explain... Thoughts?

[Coypu Hunter 486]

From my experience, it seems to be down to the following.

 

1. Weight, which needs to correspond to muzzle energy. When my 97 was sub-12 fpe, it shot average-weight (8.4-ish grains) pellets very accurately (AA DFs, Weihrauch F&Ts, JSBs not quite as well). When I V-Mached it up to 13 fpe, I had to move to JSB Exact Heavies (10.34 grains) to recapture the accuracy.

 

2. Size, which also seems to have a relationship with muzzle energy. At sub-12 fpe, my 97 preferred 4.51mm Weihrauchs and 4.50mm AAs. Now, it's 4.52mm Heavies.

 

3. Shape, which affects aerodynamic stability over longer ranges. All of the pellets normally cited as being accurate at range are domed. AA DFs, JSBs, Weihrauchs, Falcons, even Superdomes (which my rifle hates). Most of these (except Superdomes) are made by JSB, I think.

 

So, when looking for the perfect pellet for long-range accuracy, ignore the gimmicky hollowpoints, points and bullets, and go for domed; then pick a weight that suits the muzzle energy of your rifle; then try the different available head sizes until you find the most accurate one.

Edited January 16, 2015 by Coypu Hunter

[pianoman 3,589]

Coypu Hunter's answer has a lot of good sense in it.

 

I don't want to open a can of incomprehensible science but.....A diablo pellet is effectively, a ball shot that creates an efficient, equalised airflow around it, much better than other types of head design; and with a skirt that both maximises the propellant charge of air behind it and stabilizes the gyroscopic spin imparted from the rifling to the head and tail of the pellet. This is why, I think, Diablo pellets are usually better performers than others for accurate flight. They also have the effect of a blunt instrument in imparting lethal shock as hunting rounds against vermin.

 

 

You can go deep into ballistic co-efficiencies and God knows what-not. But specifically, air rifles are rarely made to produce absolutely identical figures of muzzle-energies of air blast; and their barrels are rifled with lands that are microscopically different in their laps and that makes it almost impossible to make a single-sized caliber pellet that absolutely suits each and every barrel of that calibre.

 

Even the same makes and models of air rifle are all, almost like a fingerprint's difference from barrel to barrel and pellets perform with effect influenced by those differences from barrel to barrel. For instance, you can have .22/ 5.52mm Air Arms diablo Fields performing absolutely precision accurate in one HW77 Barrel, let's say; then, be utterly hopeless in another HW77 of the same calibre.

 

And yet....Some rifles are seemingly able to perform well with a variety of different pellet makes and weights, while some others are extremely fussy about their diet!

 

I've even known a few, certain guns in my time, completely change their pellet preferences after they've been serviced with replacement internal parts such as springs etc. The change in FPE, even slight, sometimes changes and affects pellet performance for the worse. Or, not at all.

 

Fortunately, most pellets are made in differing head sizes and weights to counteract these micro-differences and produce an accurate, matching round for your make of particular rifle and its performance.

 

Simon

[Rez 4,961]

Question is answered nice one chaps.