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100 vs 200 yard groupings (Read 10326 times)

joeb33050 Frequent Elocutionist Offline Posts: 2613 Location: Marathon, FL Joined: Apr 20^th, 2004	Re: 100 vs 200 yard groupings Reply #15 - Oct 28^th, 2013 at 4:15am	Print Post
	To simplify the ratios, expected group size for 10 shot 200 yard groups is 5 shot 100 yard group size * 3.33,(1.312.545=3.33), and .54" 3.33 = 1.8" - your expected 200 yard 10 shot group size. Your 1.44" is smaller than expected but a small sample.The 1.8" is the expected average of a lot of groups. frnkeore wrote on Oct 27^th, 2013 at 4:40pm: Lefty, I think what he means is that the load had higher extreme spreads and thus more elevation variance @ 200. There is a little more than 1" elevation change for 10 fps differance at 200 with a load that starts at 1100 fps. Regarding how much the group opens, I have just had about the same results as John did between 100 & 200 yards. I shot 5, five shot groups averaging .54 (with one bad group of .8+) at 100, 2 weeks ago at Modesto and I just shot a 200 yard 10 shot group of 1.44 at our club match yesterday. Both in relative calm conditions. Frank


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joeb33050 Frequent Elocutionist Offline Posts: 2613 Location: Marathon, FL Joined: Apr 20^th, 2004	Re: 100 vs 200 yard groupings Reply #16 - Oct 28^th, 2013 at 4:33am	Print Post
	This kind of arithmetic tells the shooter if, for instance, the accuracy falls off from 100 to 200 yards. The S.D. of 10 shot groups is ~.195 * the average group size. Use the expected 200 yard 10 shot group size of John L., using the ALL ratio. That was 1.67". 95% of the time we expect group size between 1.02" and 2.32". 99% of the time we expect 200 yard group size to be between .69" and 2.65" Then John's average of 1.5" is within either expected range, and is not an indication that accuracy has fallen off from 100 to 200 yards.


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joeb33050 Frequent Elocutionist Offline Posts: 2613 Location: Marathon, FL Joined: Apr 20^th, 2004	Re: 100 vs 200 yard groupings Reply #17 - Oct 28^th, 2013 at 8:49am	Print Post
	The easy way to see if the loss of velocity over the second hundred yards affected stability is to shoot at lower velocity at 100 yards. If it's going 1400 at 100 and 1200 at 200, shoot at 1200 at 10-0 and check stability. My extensive testing at 100 yards, 314299 @ 200 gr, showed NO dramatic stability loss down to way under 1000 fps. Cat_Whisperer wrote on Oct 27^th, 2013 at 4:28pm: I'm betting, in my case, that my Unique load was just on the edge of being stable out to 100 and it fell apart shortly thereafter. (Large sight correction from 100 to 200.) where the 4759 load was considerably higher velocity and remained stable. Having said that, I find the responses here very interesting in exploring other aspects that I'd not considered. THANKS!


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westerner Frequent Elocutionist Offline deleted posts and threads record holder. Posts: 11458 Location: Why, out West of course Joined: May 29^th, 2006	Re: 100 vs 200 yard groupings Reply #18 - Oct 28^th, 2013 at 9:16am	Print Post
	I'm with Louis and Frank. If your bullets are stalling before they get to the target, push them faster. Joe.

	A blind squirrel runs into a tree every once in a while.
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shovel80 Oldtimer Offline Posts: 896 Location: Sonora,CA Joined: Jun 6^th, 2011	Re: 100 vs 200 yard groupings Reply #19 - Oct 28^th, 2013 at 9:19am	Print Post
	I think some of this may have to do with the change from super sonic to sub sonic speeds. Terry

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QuestionableMaynard8130 Frequent Elocutionist Offline Posts: 4144 Location: Benton Harbor MI Joined: Apr 17^th, 2004	Re: 100 vs 200 yard groupings Reply #20 - Oct 28^th, 2013 at 10:16am	Print Post
	Thats it, put your chrono out at 200 yards and shoot through it to check the velocities out there

	sacred cows make the best burger
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Cat_Whisperer Frequent Elocutionist Offline No 1, 9.3x74R Posts: 3877 Location: Mountains of Virginia Joined: Apr 17^th, 2004	Re: 100 vs 200 yard groupings Reply #21 - Oct 28^th, 2013 at 10:27am	Print Post
	shovel80 wrote on Oct 28^th, 2013 at 9:19am: I think some of this may have to do with the change from super sonic to sub sonic speeds. Terry It may. IF the 100 yd load was supersonic - don't know if it was. Easiest solution is simply to kick the velocity up (i.e. use the 4759 load for now - until I have time to work that up/down to optimize at 200). Maybe I can borrow JoeB's chrono to use at 200?

	Cat Whisperer (trk) Chief of Smoke Pulaski Coehorn Works and Skunk Works Drafted May 1970, Retired Maj. U.S.Army assra #9885
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Lefty38-55 Senior Forum Member Offline Posts: 366 Location: New England Joined: Sep 11^th, 2013	Re: 100 vs 200 yard groupings Reply #22 - Oct 28^th, 2013 at 10:48am	Print Post
	shovel80 wrote on Oct 28^th, 2013 at 9:19am: I think some of this may have to do with the change from super sonic to sub sonic speeds. Terry: That's exactly what I was thinking when I used the muzzleloading patched roundball example. That transition zone is known to wreak havoc ...

	All of my single shots shoot one tiny ragged hole with cast bullets ... it's just the following shots that tend to open up my groups ...
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gunlaker Frequent Elocutionist Offline Posts: 2270 Location: lower mainland, B.C. Joined: Dec 13^th, 2010	Re: 100 vs 200 yard groupings Reply #23 - Oct 28^th, 2013 at 10:59am	Print Post
	westerner wrote on Oct 28^th, 2013 at 9:16am: I'm with Louis and Frank. If your bullets are stalling before they get to the target, push them faster. Joe. I think so too. Chris.


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shovel80 Oldtimer Offline Posts: 896 Location: Sonora,CA Joined: Jun 6^th, 2011	Re: 100 vs 200 yard groupings Reply #24 - Oct 28^th, 2013 at 12:11pm	Print Post
	Seems to me supersonic velocity Starts at approx. 1128 FPS. Terry

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Cat_Whisperer Frequent Elocutionist Offline No 1, 9.3x74R Posts: 3877 Location: Mountains of Virginia Joined: Apr 17^th, 2004	Re: 100 vs 200 yard groupings Reply #25 - Oct 28^th, 2013 at 9:24pm	Print Post
	shovel80 wrote on Oct 28^th, 2013 at 12:11pm: Seems to me supersonic velocity Starts at approx. 1128 FPS. Terry Well said. Variables include temperature and humidity.

	Cat Whisperer (trk) Chief of Smoke Pulaski Coehorn Works and Skunk Works Drafted May 1970, Retired Maj. U.S.Army assra #9885
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