While I am not really "reloading" these bullets or cartridges, I am modifying them considerably, and it kinda feels like reloading so I'm putting this thread in this site.
A few years back, I fell in love with the 60-grain SSS (Sniper Subsonic) .22 rimfire cartridge made by Aguila and primed by Eley. However, the LONG, heavy, bullet would not stabilize in ANY of my several .22 rifles. I moped around for a while until Volquartsen put their 1:9-twist 10/22 on sale for "only" $150 and bought one. Sadly it's in stainless steel, not blue chrome molybdenum, but nonetheless it makes that SSS shoot VERY straight.
One of the "things" that bothered me about the SSS not stabilizing in ANY of my rifles with the standard 1:16 twist rate was that other folks whose veracity regarding firearms-related matters has been well-established to me, were reporting that the SSS didn't key-hole from their rifles. Something was amiss somewhere. Anyway it was those reliable reports that kept me after the bullet I wanted to shoot. (The SSS hits like the proverbial "ton of bricks".)
I've been thinking about that "instability" issue lately, and I think I might have come up with the explanation: I shoot most often at about sea level, and in temperatures rarely above 60 degrees Fahrenheit. Each of those conditions "thickens" the air. Denser air changes the stability equation (but not in my calculator unfortunately). Nonetheless, the denser the air the harder it is to gyroscopically stabilize a bullet.
So here's the upshot. I have joined the RimFireCentral forum. There's a fellow there (goes by 'D Rock') selling a device http://www.rimfirecentral.com/forums...do=ad&id=26980 that reshapes .22 RF bullet noses, AND uniforms their diameter. As soon as I saw the device, I bought one to use on the SSS bullets. The device comes with four "pointers":
1) A Hollow Point,
2) A Hydroshok (center post HP),
3) A flat nose/wad cutter, and
4) A round nose uniformer.
I made a fifth type - the flat nose hollow point, and I intend to modify the Hydroshok pointer so that it has a more acute angle to the hollowing part of the point. I don't particularly care for the results it produces now, but I KNOW the Hydroshok point is a real thumper. It acts like a hollow point on impact, but because of the center post, it penetrates farther than a normal HP.
Here some pictures of the results I obtained.
My thought was that in uniforming the diameter, AND reshaping the nose, the bullet would HAVE to get shorter, thereby changing the stability specs (improving them). I put the device to work immediately, and it does in fact shorten the bullets. According to my twist rate calculator, the difference in length and diameter make a big difference in the theoretical stability factor. I paperwhipped each of the four modified bullets (the four you see in the images, not the round nose) as well as the unmodified one - which is a round nose.
The results of that exercise suggest that my guess was probably correct about the stability of the unmodified bullet varying with where one is when one shoots it. I'll post some screen shots of the tables, and if it ever stops raining I'll see what they actually do instead of what they do "theoretically". (We set a record for consecutive days of measurable rain this summer - 30. It stopped for 3 days, then started up again, and we're working on another 10 in a row. :angry
Tables to follow.