For .30 cal:"30cal"Harry: "Pellets with heads larger than groove size are just asking to be yaw-loaded as they are forced into the rifling before or during firing, regardless of skirt size."
Harry I think you just provided a possible answer to the question I asked. About the difference between using a sizing die and letting the breach size the pellet. Pre sizing (and of course sorting out ones that are to small) allows the pellet to load straight into the breach with out the chance of yaw loading and that's why its better. Is that the main reason?
It's one very good reason I have concluded.
Consistency in the dynamics of getting the pellets all started and accelerated the same is a related reason. Having them all have the same inertia response to the charge surely involves having the same initial frictional resistance which must relate to variations or lack of variations between pellet and barrel fit. Sizing correctly surely helps that.
Though not necessarily directly related to sizing, another variable to note for long range precision shooting, is pellet weight. A tiny weight variance (as % of pellet weight) doesn't seem to matter much out to near 50 yards depending upon calibre/weight. Then further out it begins to matter. In close it isn't always the result one expects either. You probably realize that a very heavy pellet from a tin may dwell in the barrel longer and exit when the barrel may have kicked up a little further and thus at close-in range impact higher. Further out it may impact the same as the others, then from there on out impact lower. ... Regards, Harry.
For Aaron:
A true size .30 cal / 7.62 mm groove would get pellets sized at 7.62 for my money. Bullets the same too - if the barrel was either true cylindrical, or fractional full length bore tapered from hammer forging or seriously good lapping. I bow to Unrepentantsinner's work and conclusions that choked muzzles are not the go for air bullets, though if done to the smallest degree may not be too drastic. His extreme range (in the true sense) precision shooting was ground breaking for air power with bullets.
Aaron your response contributions to this initial post were excellent; and I understand how much time and effort you put into presenting your material and in handling "discussion" to a satisfactory conclusion. You get an A tick from me there.... Best regards, Harry.
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