Author Topic: Texan 308 world recored  (Read 10057 times)

nielsenammo

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Re: Texan 308 world recored
« Reply #60 on: July 30, 2017, 04:03:41 PM »
I thank you.  Yes this was done with my labradar at my campsite.  I am waiting for Bob to post the actual g1 bc.
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oldpro

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nielsenammo

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Re: Texan 308 world recored
« Reply #62 on: July 30, 2017, 04:20:38 PM »
I know how to calculate, as you can see, David is a tad off.  I  just wanted to give Bob the honors.
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rifle 50

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Re: Texan 308 world recored
« Reply #63 on: July 30, 2017, 04:22:19 PM »
I shot the Hunter Supply bullet this weekend.  I shot it in a Slayer with the same twist barrel with a different tune that Texan but close enough for sure.  I am going to post the data here and I am sure Bob will do the honors.  I did not have internet, or even text, over the weekend where we were hunting so I have not calculated it yet but I did get an idea of roughly where it is. 

So I only recorded 6 shots because they were so close I knew they are good numbers and the BC testing we are doing is to see if the bullet is a magnitude better than all the other bullets on the market, not to get a BC that we can use to calculate drop and moa with.  I did take more shots than what I recorded and they were all the same fps loss from muzzle to 50 yards.

Muzzle/50 yard fps     fps loss
691/674          17
704/683          21
696/677          19
688/664          24
686/666          22
688/665          23

Altitude 3925 feet
Temp 95 deg F
Baro Pres 27.06 in hg
Wet/Dry Bulb 63.3/42.9
Humidity 18.0 %

Using the JBM BALLISTIC CALCULATOR, the average of 21 fps lost over 150 ft/50 yds calculates to .175 B.C. at the speed they were shot..........

Carl
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oldpro

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Re: Texan 308 world recored
« Reply #64 on: July 30, 2017, 04:27:37 PM »
I know how to calculate, as you can see, David is a tad off.  I  just wanted to give Bob the honors.
I know You do Nick and Bob is working on a more technical write up than I could possibly do this is not my cup of tea and more suited to your and Bobs skills just thought I would add a link for people who donot know how to check it themselves.

rsterne

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Re: Texan 308 world recored
« Reply #65 on: July 30, 2017, 04:30:24 PM »
Is the 27.06" your station (ambient) pressure, or corrected to sea level for your 3925' altitude?....

Bob
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nielsenammo

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Re: Texan 308 world recored
« Reply #66 on: July 30, 2017, 04:33:17 PM »
I shot the Hunter Supply bullet this weekend.  I shot it in a Slayer with the same twist barrel with a different tune that Texan but close enough for sure.  I am going to post the data here and I am sure Bob will do the honors.  I did not have internet, or even text, over the weekend where we were hunting so I have not calculated it yet but I did get an idea of roughly where it is. 

So I only recorded 6 shots because they were so close I knew they are good numbers and the BC testing we are doing is to see if the bullet is a magnitude better than all the other bullets on the market, not to get a BC that we can use to calculate drop and moa with.  I did take more shots than what I recorded and they were all the same fps loss from muzzle to 50 yards.

Muzzle/50 yard fps     fps loss
691/674          17
704/683          21
696/677          19
688/664          24
686/666          22
688/665          23

Altitude 3925 feet
Temp 95 deg F
Baro Pres 27.06 in hg
Wet/Dry Bulb 63.3/42.9
Humidity 18.0 %

Using the JBM BALLISTIC CALCULATOR, the average of 21 fps lost over 150 ft/50 yds calculates to .175 B.C. at the speed they were shot..........

Carl

Carl, was that a G1 BC?  Did you calculate the G1 and G7.  He used a G7 calculator so we need a G7 BC.  He stated he used .271 in a G7 calculator.
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Re: Texan 308 world recored
« Reply #67 on: July 30, 2017, 04:36:40 PM »
The best I could come up with was .215 in G1 and average of .185 in G1 now same data in G7 .126 so basically a whiff on the target....

oldpro

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Re: Texan 308 world recored
« Reply #68 on: July 30, 2017, 04:50:07 PM »
 Here is a calculator to correct for above sea level barometer pressure  http://www.csgnetwork.com/barcorrecthcalc.html

rifle 50

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Re: Texan 308 world recored
« Reply #69 on: July 30, 2017, 04:54:32 PM »
I shot the Hunter Supply bullet this weekend.  I shot it in a Slayer with the same twist barrel with a different tune that Texan but close enough for sure.  I am going to post the data here and I am sure Bob will do the honors.  I did not have internet, or even text, over the weekend where we were hunting so I have not calculated it yet but I did get an idea of roughly where it is. 

So I only recorded 6 shots because they were so close I knew they are good numbers and the BC testing we are doing is to see if the bullet is a magnitude better than all the other bullets on the market, not to get a BC that we can use to calculate drop and moa with.  I did take more shots than what I recorded and they were all the same fps loss from muzzle to 50 yards.

Muzzle/50 yard fps     fps loss
691/674          17
704/683          21
696/677          19
688/664          24
686/666          22
688/665          23

Altitude 3925 feet
Temp 95 deg F
Baro Pres 27.06 in hg
Wet/Dry Bulb 63.3/42.9
Humidity 18.0 %

Using the JBM BALLISTIC CALCULATOR, the average of 21 fps lost over 150 ft/50 yds calculates to .175 B.C. at the speed they were shot..........

Carl

Carl, was that a G1 BC?  Did you calculate the G1 and G7.  He used a G7 calculator so we need a G7 BC.  He stated he used .271 in a G7 calculator.

That would be G1.................Carl
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Re: Texan 308 world recored
« Reply #70 on: July 30, 2017, 04:57:30 PM »
deleted
« Last Edit: July 30, 2017, 07:10:54 PM by oldpro »

nielsenammo

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Re: Texan 308 world recored
« Reply #71 on: July 30, 2017, 05:32:38 PM »
I added the JMB Ballistics results for both the G1 and G7.  In summary the G7 BC came out to .103 measured BC.  Nowhere near the BC used of .271.
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rsterne

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Re: Texan 308 world recored
« Reply #72 on: July 30, 2017, 07:33:31 PM »
I admit to being confused by the 27.06" barometric pressure, at an altitude of 3925'.... If that was station pressure, then corrected to sea level it works out to 31.03", which is extremely high.... If that was corrected to sea level, it represents an extreme low, and when corrected to 3925' is a station pressure of only 23.08"....

Record worldwide barometric pressures are 25.7" on the low end, and 32" on the high end, corrected to sea level.... For California, the record low is 28.9", and the record high is 30.6", corrected to sea level.... Therefore, 27.06" at sea level is out of range of anything likely, but so is 31.03" on the high end....

Using 27.06" as the station (ambient) pressure gives the highest possible BC when corrected for standard conditions at sea level, so let's assume that is the case.... We then have two choices, we can use the average muzzle velocity and 50 yard velocity.... OR to be the most generous we can use the shot that had the least difference between the two velocities (17 fps), which is shot #1.... I used 95*F and 18% humidity, and 27.06" station (ambient) pressure....

Using the JBM Ballistics Calculator, I got the following results....

Average MV = 692 fps.... Average 50 yd. velocity = 672 fps....

Calculated BC (G1) = 0.182
Calculated BC (G7) = 0.107

Best case MV = 691 fps.... 50 yd. velocity = 674 fps....

Calculated BC (G1) = 0.215
Calculated BC (G7) = 0.126

Using ChairGun I got the following results....

Average MV = 692 fps.... Average 50 yd. velocity = 672 fps....

Calculated BC (G1) = 0.182
Calculated BC (G7) = 0.107

Best case MV = 691 fps.... 50 yd. velocity = 674 fps....

Calculated BC (G1) = 0.215
Calculated BC (G7) = 0.126

Note that the two calculators return identical results.... I feel that since the range of delta values is relatively small, using the best shot would be just as unfair as using the worst shot.... so if I was going to use a BC for this bullet, I would use the G1 model as being the closest representation of bullet shape, and would therefore use a BC (G1) of 0.182 at a velocity of about 700 fps.... If for some reason you wanted to use the G7 model, then the appropriate BC (G7) would be 0.107.... There is a potential SMALL discrepancy for the BC calculations because the claimed MV of the original shot was 986 fps, instead of the average in these tests of 692 fps.... but I would sincerely doubt if the Subsonic BC of this bullet was the 0.271 claimed by RCBS, even if that was the G1 number.... That is more likely a measurement of the BC (G) well into the Supersonic range that the bullet was originally intended for....

If we use those BCs, and correcting for the altitude of the shots of 7800 ft. and assuming a "normal" day in other respects.... and using the stated MV of 986 fps, we get the following at 1100 yds, assuming sighted at 100 yds. and a 10 mph crosswind....

BC (G1) = 0.182
Drop = 3283" (274 ft.)
Velocity = 549 fps
Energy = 103 FPE
Drift = 304" (25 ft.)

BC (G7) = 0.107
Drop= 3086" (257 ft.)
Velocity = 568 fps
Energy = 110 FPE
Drift = 274" (23 ft.)

These numbers are so far different from those originally posted (Drop = 2289", 217 FPE, and no correction for the wind).... that the original claims simply make no sense to me....

Bob
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nielsenammo

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Re: Texan 308 world recored
« Reply #73 on: July 30, 2017, 07:55:27 PM »
Bob could be right about the BP reading but that is what my Kestral read so that is what I recorded.  No matter for this purpose anyway, the numbers are off by a magnitude, in fact, even further than before the BC testing was done from I thought it was.
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Re: Texan 308 world recored
« Reply #74 on: July 30, 2017, 08:25:15 PM »
 I was also struggling with the BP and ended up deleting a post because I couldnt make since of the correct BP......BUT.....No matter how you choose to adjust the numbers using BP or G1 OR G7 or even altitude (unless you live in the stratosphere) it makes no since its simply off that much!!! Cant be done as originally posted its that simple. Ok so lets get to whats really important at least to me and thats the numerous claims of a world record I hope this gets rectified and the record returned to its rightful owner at this time CARL AKA Rifle50.  Bobs numbers are exactly the same as the ones I came up with earlier and I double checked my math and can say without doubt Bob and Nick were correct from the start but its very important to get results from more than one entity and to have many eyes look it over. WORLD RECORDS should not be taken lightly this is how we push each other to new limits. Furthermore I see no reason to beat this dead horse unless their is something useful to be added to this thread. Opinions please.
« Last Edit: July 30, 2017, 08:33:09 PM by oldpro »