Hi Guys. I'm new to this site, and although I don't shoot LD, I have a question that perhaps the expertise on this board can help me with . . .
I apologize in advance for the long post.
Last weekend I attended the Bridgeville Pistol & Rifle Club's 600 yard Oyster Shoot, a 'fun' 600 yard group shooting competition in Delaware. Competition consisted of shooting two 5-shot groups for group, with the smallest group to count. I am not a LD shooter, but dragged out my 6PPC benchrest rifle to shoot, just for fun. I also threw in my medium range (by my standards!) .22-250 Ackley varmint rifle and a few cartridges left over from summer groundhoggin', just to see what it would do.
Winds were relatively strong (15-25 mph), gusting and switching from left to right. The only flag was on a ~40 ft. flagpole at about 300 yards (almost useless). While driving down, I reviewed some ballistic tables for the .22, which showed that the .255 BC bullets should drift about 62" in a 15 mph 90 degree crosswind. Ouch!
As it turns out, the .22-250 Ackley, shooting moly coated 55 gr. Hornady VMax varmmint bullets at ~3800 fps first shot a 5 3/4" and then a 5" group to win this informal competition. Groups shot by other rifles included 5 1/8" and 6 3/8" groups by a Hi-Power shooter with a 6BR shooting 107 gr. Sierra's, and a 6 3/4" group from a .243 Ackley shooting 67 gr. BT Hollister bullets. No other groups were in the 5" or 6" range with few others below 10", although there were numerous .30 caliber rifles shot including a .300 Ultra, .300 WinMag, and 30BR. My small groups were not due to wind reading shooting skill(?), as I shot completely horizontal 10" and 11" groups with my 6PPC.
This has sort of rocked my world with respect to the windage ballistic performance of small, light, low BC bullets. By my reckoning, there is NO WAY that rifle with those bullets should have been able to shoot a 5" group in that wind, let alone two, and on a relative basis, should NOT have been able to shoot the smnallest group compared to the other rifles.
Regardless of what you say, I'd say it had a good bit to do with your wind reading. You read the conditions & timed your shots well. Well, maybe a little luck too. [img]images/icons/smile.gif[/img]
I shoot 55 gr ball at 600 yards regularly in military combat matches, where we are restricted to rack grade M-16's and issue 55 grain ammo. The wind drift in wind like that is amazing. I watched trace for a guy one day, it was going completely off of a 6 ft by 6 ft backer, then fading back in for hits in the black.
Don't think that the little bullets will outshoot the 107's in 6mm. You had a good relay on a good day, but overall, the light 22's will get hammered at those ranges.
Thanks for your responses. I may be thinking about this too much. And still am . . .
The two small groups (5" and 5 3/4") with the .224" 55 gr. bullets were shot about half an hour apart. So were the two PPC groups of 10" and 11". While I waited for 'let-ups' with all groups, I really didn't get any, and don't think I read the wind all that well.
What is of interest is that when I picked up this varmint rifle last year with the new barrel installed, the smith (a top BR smith) told me the chamber ended up less than .0001" out from the bore. Even this top guy was obviously proud of this chambering job, and invited me to look at it through the borescope. It was perfectly concentric. I have done minimal range work with this barrel, just verifing a good load (capable of low .2's at 100), and have used it almost exclusively on groundhogs. My impressions from field shooting of this barrel and chambering (subject to all the randomness, vagaries and interpretation issues of field shooting) indicate that this barrel shoots extremely well, and doesn't require the windage hold that previous barrels did shooting the same bullets. This barrel/chambering shoots extremely well, far better than the almost identical barrel (Hart LV) it replaced, done by the same smith with the same reamer.
What I have been wondering is, is it possible that this barrel is a partial 'Hummer'? And could the excellent chambering job (near-perfect, even for BR standards) be a significant contributing factor to Hummer-like (wind deflection resistance) qualities? Or, is it as you suggest, just the luck of the draw with respect to the wind. (I realize the statistical insignificance of two groups!)
Anyways, fun to think about. And as I have two 700S actions (.243 and 6mm) waiting to be barreled for longer distance groundhog shooting (~500 to 800 yards), I am paying close attention to theoretical and real world ballistic performance.