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100 vs 200 yard groupings (Read 10316 times)

Cat_Whisperer Frequent Elocutionist Offline No 1, 9.3x74R Posts: 3877 Location: Mountains of Virginia Joined: Apr 17^th, 2004	100 vs 200 yard groupings Oct 26^th, 2013 at 11:30pm	Print Post
	An old lesson. 100 yard good tight groups may or MAY NOT yield good 200 yard groups. Took to the range 3 loads for the same bullet - 2 close together using a light load of Unique and another that kicked bit too much (458 WM with 385gr bullet) using 4759. At 100 yards I had 4 bullets touching or nearly so with one of the loads using Unique. Stiffer load using 4759 picked from a load manual - lightest load given. At 200 yards the 4759 did 4 shots in a vertical string about 3" tall. (ok for Iron Sights) BUT the "good loads" (at 100 using Unique - LIGHT loads) were ALL OVER the paper with 3 or 4 hitting the paper at 200. SIMPLE, OLD lesson - accuracy of a given load CAN fall apart at longer ranges than which was tested.

	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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shovel80 Oldtimer Offline Posts: 896 Location: Sonora,CA Joined: Jun 6^th, 2011	Re: 100 vs 200 yard groupings Reply #1 - Oct 26^th, 2013 at 11:49pm	Print Post
	Myself, I don't usually shoot loads for groups any closer than 200 yards. And Normally No less than 10 shot groups. I only shoot closer if Rim Fire, or just getting on paper. Terry

	ASSRA Member # 11021
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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 #2 - Oct 27^th, 2013 at 12:02am	Print Post
	shovel80 wrote on Oct 26^th, 2013 at 11:49pm: Myself, I don't usually shoot loads for groups any closer than 200 yards. And Normally No less than 10 shot groups. I only shoot closer if Rim Fire, or just getting on paper. Terry I wish! The ranges I have access to are 100 yds.

	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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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 #3 - Oct 27^th, 2013 at 12:52am	Print Post
	The 200 yard load for my 32-40 Krag/Rem rifle, is lucky to hit the target frame at 300. Think they go into a dead stick power stall in a vortex funnel maneuver at about 245 yards. Thats the sort of thing that can happen when you're on the ragged edge of perfection and disaster. Its a razor edge, a fine line we tippy toe around on. Joe.

	A blind squirrel runs into a tree every once in a while.
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JLouis Frequent Elocutionist Offline Posts: 10625 Joined: Apr 8^th, 2009	Re: 100 vs 200 yard groupings Reply #4 - Oct 27^th, 2013 at 1:02am	Print Post
	If breach seating and getting 5-5shot groups averaging under a 1/2 day in and day out at a 100yds. moving out to 200yds has yielded 10 shot groups that are averaging 11/2. Slight increase in powder from 100-200yds. is called for, right now I am at an increase of 5 tenths grains. Currently working on getting those 200yd. averages down yet more. Rifle is a CPA 52 32-40, bullet is a 195gr. Darr flat nose. JLouis

	" It Is Better To Now Have Been A Has Been Than A Never Was Or A Wanna Be "
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Chickenthief Junior Member Offline Posts: 81 Location: Here Joined: Aug 5^th, 2013	Re: 100 vs 200 yard groupings Reply #5 - Oct 27^th, 2013 at 11:58am	Print Post
	Lots of guestimates but here goes: I took a Lee 340grain boolit (it was in QL) has a BC of .211 I assumed 8grains of Unique I assumed 24" barrel That gives: V0 = @865fps V100 = @ 805fps V200 = @ 750fps But time of flight is another story: 100yds = .36sec 200yds = .75sec In 3/4 sec the wind can reac havoc with a boolit. Even light wind. 5mph will toss the boolit +-5inch at 200yds. If 100yds is zero then 200yds has a 52" drop. Like riding a bicycle, it is quite stable when speed is lowered and then suddenly it will toss you of.


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Chickenthief Junior Member Offline Posts: 81 Location: Here Joined: Aug 5^th, 2013	Re: 100 vs 200 yard groupings Reply #6 - Oct 27^th, 2013 at 12:01pm	Print Post
	JLouis wrote on Oct 27^th, 2013 at 1:02am: If breach seating and getting 5-5shot groups averaging under a 1/2 day in and day out at a 100yds. moving out to 200yds has yielded 10 shot groups that are averaging 11/2. Slight increase in powder from 100-200yds. is called for, right now I am at an increase of 5 tenths grains. Currently working on getting those 200yd. averages down yet more. Rifle is a CPA 52 32-40, bullet is a 195gr. Darr flat nose. JLouis But there is a slight difference between a 195gr .32" boolit and an aerodynamic disaster that is .458" and only weighs 385gr.


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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 #7 - Oct 27^th, 2013 at 1:18pm	Print Post
	what is the BC for that sub400 gr bullet, 100 to 200 doubles the distance the wind can play with your "lite" bullet, particularly if it is slowing down much out at the far end

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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 #8 - Oct 27^th, 2013 at 4:06pm	Print Post
	I'll bet that at least some of it has to do with high velocity variation. That Unique load probably has more variation than the SR-4759 load. Chris.


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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 #9 - Oct 27^th, 2013 at 4:15pm	Print Post
	gunlaker wrote on Oct 27^th, 2013 at 4:06pm: I'll bet that at least some of it has to do with high velocity variation. Chris, do you mean the negative effects that can come into play as a bullet is losing energy in flight? All I can envision is a typical roundball trajectory, where you'll be on paper @ 75-yds and no where to be found @ 100!

	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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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 #10 - Oct 27^th, 2013 at 4:28pm	Print Post
	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!

	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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frnkeore Frequent Elocutionist Offline Posts: 7267 Location: Central Point, OR 97502 Joined: Jun 16^th, 2010	Re: 100 vs 200 yard groupings Reply #11 - Oct 27^th, 2013 at 4:40pm	Print Post
	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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gunlaker Frequent Elocutionist Offline Posts: 2270 Location: lower mainland, B.C. Joined: Dec 13^th, 2010	Re: 100 vs 200 yard groupings Reply #12 - Oct 27^th, 2013 at 8:59pm	Print Post
	Yessir Frank that's exactly what I meant. As an example, one of my .38-55 loads shot very well at 100m ( for me ), with 8 out of ten shots having under 1/2" of vertical and maybe an inch of horizontal. If I remember correctly there was a spread of about 25fps in velocity ( which is especially terrible with black powder) when I shot ten at 200m. At 200m the loads fell apart and went into over 4" of vertical which I what you'd expect with those sort of velocity variations I think. Chris.


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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 #13 - Oct 27^th, 2013 at 11:06pm	Print Post
	QuestionableMaynard8130 wrote on Oct 27^th, 2013 at 1:18pm: what is the BC for that sub400 gr bullet, 100 to 200 doubles the distance the wind can play with your "lite" bullet, particularly if it is slowing down much out at the far end Good question, don't know. The difference was radical! From a right-much good 100yd group (1-2") to only 3 or 4 on the 200yd target. Not to say wind didn't have a big effect, but likely not the greatest cause.

	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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joeb33050 Frequent Elocutionist Offline Posts: 2613 Location: Marathon, FL Joined: Apr 20^th, 2004	Re: 100 vs 200 yard groupings Reply #14 - Oct 28^th, 2013 at 4:07am	Print Post
	If 5 shot groups average .5" at 100 yards; then 10 shopt groups would average .655", because the ratio is 1.31 then 200 yard 10 shot groups would average 1.83" using the CBA PBB 200/100 avg. of 90 entries of 2.798 and 200 yard 10 shot groups would average 1.67" using the CBA ALL 200/100 avg. of 506 entries of 2.545 At 1.5" you're shooting as expected or a bit better JLouis wrote on Oct 27^th, 2013 at 1:02am: If breach seating and getting 5-5shot groups averaging under a 1/2 day in and day out at a 100yds. moving out to 200yds has yielded 10 shot groups that are averaging 11/2. Slight increase in powder from 100-200yds. is called for, right now I am at an increase of 5 tenths grains. Currently working on getting those 200yd. averages down yet more. Rifle is a CPA 52 32-40, bullet is a 195gr. Darr flat nose. JLouis


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