| The explanation for the unusually good-for-HV ammo results is straightforward, if unexpected. It appears that since the vertical spread is relatively small at 200 yards, the ammo has a relatively small extreme spread. It also must be relatively consistent in its component characteristics, with bullets seated consistently in the casings. In other words, this was a particularly good batch of high velocity .22LR ammo, not cursed with the usual and expected high extreme spread and inconsistent components and assembly. More interesting and important, Is there such a thing as "supersonic transition" that's supposed to prevent good results? The ammo in question has a factory-rated MV of 1280 fps and never exceeds "transonic" velocities. In order for projectiles to experience accuracy robbing transonic turbulence, they must slow down from higher velocities into the transonic zone, which is from about 1340 to 890 fps. When they do, they experience transonic turbulence. Depending on the distance, centerfire ammo can be at risk of experiencing this challenge to accuracy. Most high velocity .22LR ammo is not -- unless it's hyper velocity ammo with MVs in excess of about 1340 fps. It was confirmed in 1990 by Robert McCoy that .22LR ammo with transonic zone velocities (from about 1340 fps to 890 fps) doesn't suffer from the increased pitching and yawing that causes the flight instability associated with bullets slowing down into the transonic zone from considerably greater velocities. See conclusion #5, p.11 in Robert McCoy "AERODYANMIC CHARACTERISTICS OF CALIBER .22 LONG RIFLE MATCH AMMUNITION" https://apps.dtic.mil/dtic/tr/fulltext/u2/a229713.pdf |
Loved going thru that link...reminded me of looking at a microfiche..thank you for that info!!
Thank you! I just got some test lots today..Hoping it doesn't snow much this weekend.
You may get more snow than we will get, but it is going to be COLD this weekend.
One item to note is that R100 is on the faster side of standard velocity. IMHO, not an issue if it shoots!
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I was able to shoot this weekend. at 35 degrees I still got 1150fps..the lot I went with had an SD of 4.5 for a box. I read your post and went and checked the 200 yard targets (had them in the car). I have 1.75'' vertical spread at 200. Was only 20 shots.Just for comparison...
RWS 100
50 at 200
Jaia, I've been wondering if you have been reading the wind and holding off to compensate or if you use the same aiming point for all shots?
RWS R50
50 at 200
Jaia, I've been wondering if you have been reading the wind and holding off to compensate or if you use the same aiming point for all shots?
Lapua CenterX
50 at 200
SK Pistol Match Special 40 grain round nose 22lr Rated 955 fps from a pistol, from a rifle add 125 fps 40 fps ES and 4.5 inches of vertical, pretty decent target ammo Same conditions as the SK Flatnose but better vertical. jaia---- Thanks for those test results. You are doing a lot of work...
SK Pistol Match Special
50 at 200
5 inches of vertical is decent for CCI SV. Offhand is just gravy. ;) The wind was pretty calm, I was trying to get some sighters for a 200 yard egg challenge on M14br.com. Only have three shots to hit an egg, no sighters! If all misses, have to wait another day, yikes!:eek:
SK Semi-Auto
50 at 200
Breaking in a new 22lr factory barrel for my CZ 455 Varmint. Link to break-in thread, borescope pics https://www.rimfirecentral.com/forums/showthread.php?t=1211851 Might as well use up some of the bulk cartridges. Winchester 36 grain cphp rated 1280 fps CZ 455 Varmint, factory barrel, heavy...
SK Biathlon Sport
50 at 200
That target was shot vertical, not horizontal, dang picture!:confused:
