And here we go again, one .223 comming up.



Author Topic: And here we go again, one .223 comming up.  (Read 9855 times))

Offline rsterne

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Re: And here we go again, one .223 comming up.
« Reply #100 on: June 16, 2018, 05:11:58 PM »
Timo sent me the raw data, and discarding the readings past 112 M, using a Polynomical Trendline, and correcting for his atmospheric conditions, I got a BC (G1) of 0.365 for the 57 gr. bullet.... pretty fantastic....

Bob
  • Coalmont, BC, Canada
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), .22 QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Bench PCP, 6mm Regulated PCP and .257 Unregulated, Three BRods.

Offline TPL

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Re: And here we go again, one .223 comming up.
« Reply #101 on: June 16, 2018, 05:46:34 PM »
I still think it is not true. That is about the same BC I got but when I compare it to resulted scope elevation from several ballistic calculators it doesn't fit at all.

For this bullet I don't have a match but speaking of my .452 XP I have calculated BC 0.268 from Labradar velocity data. Real one which appears to be right on trajectory calculator is 0.171. With that interpolated BC it gives me perfect corrections for every distance. Measured and calculated by velocities seems much too high.

I could have use for explanation of this if anyone have.
« Last Edit: June 16, 2018, 05:50:07 PM by TPL »
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Offline rsterne

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Re: And here we go again, one .223 comming up.
« Reply #102 on: June 16, 2018, 06:16:25 PM »
Unless the LabRadar data is wrong.... I have no other logical explanation....  :-\

Yes, 0.365 does seem way too high, that indicates a Form Factor of 0.45, which is pretty much unheard of....  ::)

Not many FB bullets have a FF lower than 1.0, which with the SD of 0.164 would give a BC of the same.... If that is the NOE 57 gr., they give the calculated BC at 0.200, but no velocity stated of course....

Bob
« Last Edit: June 16, 2018, 06:42:07 PM by rsterne »
  • Coalmont, BC, Canada
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), .22 QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Bench PCP, 6mm Regulated PCP and .257 Unregulated, Three BRods.

Offline TPL

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Re: And here we go again, one .223 comming up.
« Reply #103 on: June 17, 2018, 03:34:39 AM »
I think the data is wrong. We have tested it against chrono and velocity is correct but that long distance just can't be. I'll check that when possible.
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Offline rsterne

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Re: And here we go again, one .223 comming up.
« Reply #104 on: June 17, 2018, 05:24:46 PM »
Weird thing is that if you take the time of flight to 111.78 M it is 0.347 sec, which works out to an average of 322 m/s.... That is pretty much exactly on the trendline.... If the distances were wrong (ie shorter than the data string), then the average velocity to any given distance would not agree with the trendline average....

I have no idea what the problem is, but like you, I don't believe the data....

Bob
  • Coalmont, BC, Canada
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), .22 QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Bench PCP, 6mm Regulated PCP and .257 Unregulated, Three BRods.

Offline TPL

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Re: And here we go again, one .223 comming up.
« Reply #105 on: June 18, 2018, 04:31:32 AM »
I checked that too and all the distance, speed and flight time values match together which is pretty weird. What I can think maybe there is slightly wrong clock frequency. Time would be incorrect and if it calculates distance from time all seems to match. Speed comes from doppler shift so it can be right at close range. But without knowing how it really works in details this is only quessing.
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Offline rsterne

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Re: And here we go again, one .223 comming up.
« Reply #106 on: June 18, 2018, 07:50:12 PM »
If the clock rate is wrong, the near velocity should be wrong as well.... IMO.... I'm at a total loss, but I would use a conventional Chrony, and check it at 5 yards and 70 yards and see what you get....

Bob
  • Coalmont, BC, Canada
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), .22 QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Bench PCP, 6mm Regulated PCP and .257 Unregulated, Three BRods.

Offline Bill G

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Re: And here we go again, one .223 comming up.
« Reply #107 on: July 03, 2018, 08:18:06 PM »
Maybe reading in yards and your thinking in meters? setting issue? Just making guesses because it is something I would probably do. then beat myself up for a week :-[
  • Nicholasville KY
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Offline Jim Holmgren

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Re: And here we go again, one .223 comming up.
« Reply #108 on: July 29, 2018, 02:55:56 PM »
Truly amazing craftsmanship! ;)

Do you have some info/pics to share about the balanced valve you made?

Also do you use a probe or do you seat the bullets by hand?

« Last Edit: July 29, 2018, 03:05:37 PM by Jim Holmgren »
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Offline MJP

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Re: And here we go again, one .223 comming up.
« Reply #109 on: July 29, 2018, 03:56:25 PM »
Thanks Jim,
Well the valve is something I wont share in open forum, but you can get similar designs from cothran.
I use retractable probe on this build and it will be utilized on future builds as well.

Marko
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Impossible just takes a little bit longer to achieve.

Offline Jim Holmgren

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Re: And here we go again, one .223 comming up.
« Reply #110 on: July 29, 2018, 04:15:31 PM »
Thanks Jim,
Well the valve is something I wont share in open forum, but you can get similar designs from cothran.
I use retractable probe on this build and it will be utilized on future builds as well.

Marko

Thanks!

How does the retractable probe work? I quess it is not a J-slot type or is it?
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Offline MJP

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Re: And here we go again, one .223 comming up.
« Reply #111 on: July 30, 2018, 12:49:29 AM »
You can see it in the last picture I posted. Bolt is in the locked position and there is a slot in front of it. You just seat the bullet and retract the bolt, lock it down.

Marko
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Impossible just takes a little bit longer to achieve.

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