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Old 03-19-2013, 08:27 PM   #41 (permalink)
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Yeah ive though about running a mini with a 13ci and rotor as a back up for retreats but carrying it would kind kill my play style...only way i see of doing it would be to carry with a chalker quick release harness to my spot, disconnect it and set it down until needed. I'll probably still opt for a pistol though, its more my style. I'm doing a extreme 24hr game in october this year and trying to find the right balance between mobility and firepower. I'll have to carry in everything ill need for the entire 24 hrs with no paint or air refills. So far im leaning towards first strike rifle of some sort and a pistol and hopefully someone else will take up the heavy gunner role so i can stay light.
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Old 08-23-2013, 10:53 AM   #42 (permalink)
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FSR Testing (smooth bore and rifled)

UV Halo as with others in this group have done substantial testing in relation to fs rounds. I remember reading a writeup by UV regarding ballistics of the rounds. I believe that he was able to estimate BC based on round drop at a specific range. Up till recently I have been using these numbers to calculate ballistics. We recently purchased two light sensitive chronographs. We set these two chronographs 100 feet apart and shot the SAR12 through both with the same shot. What we found was not suprising, but it did give us scientific data to proceed with. We found that the difference in velocity of a FS round at 100 feet was around 25 fps when comparing a rifled barrel and a smoothbore barrel. Obvious was the fact that the rifled barrel was more efficient. Both barrels were within .002 inch on bore diameter, thus we can neglect bore issues. Both tests were set to which the projectile left the barrel at 300 fps, and as advertised the shots didn't deviate more than plus minus 1 over testing. Regulator adjustments were necessary when we switched between the 20inch rifled barrel and the 16 inch CP barrel. Obviously both barrel manufacturers are known for quality.

This test validates the theory of prespinning the projectile makes for a more efficient flight. Finally we have started to evaluate which ballistic model to be using for the FS projectile, and it seems that the best bc model is the GA as the cross section of air gun pellets are very similar. We also did this test with paintballs and found that the BC for a paintball is .011 using the GS model

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Old 08-23-2013, 11:28 AM   #43 (permalink)
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Thanks for doing that David! It's great to have the info.
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Old 08-23-2013, 01:11 PM   #44 (permalink)
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More testing the better!
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Old 08-23-2013, 01:14 PM   #45 (permalink)
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What your determined ballistic coefficient for FS?
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Old 08-24-2013, 01:23 AM   #46 (permalink)
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Quote:
Originally Posted by CarmatechEng View Post
UV Halo as with others in this group have done substantial testing in relation to fs rounds. I remember reading a writeup by UV regarding ballistics of the rounds. I believe that he was able to estimate BC based on round drop at a specific range. Up till recently I have been using these numbers to calculate ballistics. We recently purchased two light sensitive chronographs. We set these two chronographs 100 feet apart and shot the SAR12 through both with the same shot. What we found was not suprising, but it did give us scientific data to proceed with. We found that the difference in velocity of a FS round at 100 feet was around 25 fps when comparing a rifled barrel and a smoothbore barrel. Obvious was the fact that the rifled barrel was more efficient. Both barrels were within .002 inch on bore diameter, thus we can neglect bore issues. Both tests were set to which the projectile left the barrel at 300 fps, and as advertised the shots didn't deviate more than plus minus 1 over testing. Regulator adjustments were necessary when we switched between the 20inch rifled barrel and the 16 inch CP barrel. Obviously both barrel manufacturers are known for quality.

This test validates the theory of prespinning the projectile makes for a more efficient flight. Finally we have started to evaluate which ballistic model to be using for the FS projectile, and it seems that the best bc model is the GA as the cross section of air gun pellets are very similar. We also did this test with paintballs and found that the BC for a paintball is .011 using the GS model

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David- actually my ballistic coefficient is derived from a 19 shot test sample of rounds fired over two chrono's 100ft apart by Punkworks (they did the test before consulting me,l and unfortunately the thread containing the majority of the information got corrupted and lost).

Also, you don't need nor benefit from having the chrono's so far apart. You just need to be sure the difference in velocity is outside the error of the chrono's being used. Over a longer distance, I believe due to the arc required, gravity may start to be an influence (how much? I'm not sure).

That's cool to hear about the GA/GS Models- That's a new feature in Chairgun 4 that wasn't around when I was running my numbers. However, I'd like to know why you think the GA model is better for FS rounds. I ask because the Diabolo pellet it is based on is very 'waisted' with a relatively flatter nose than an FS round.

My last question for now: I understand if the answer will be "No" as I understand you're running a business and likely doing all of your testing on the 'company's dime'. But, I must ask anyways:

Can you release the raw data and testing parameters (indoors/outdoors, elevation, for community analysis? Myself, and many others would find this this information beneficial and much more valuable than the conclusion.

Quote:
Originally Posted by tangus999 View Post
What your determined ballistic coefficient for FS?
I found it to be .0162 at 1000ft altitude, 70deg F when fired from a smoothbore barrel.
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Unfortunately all of you have played the one "speedball" game of paintball for so long you can't conceive of other ways to do this and hence any new ideas seem stupid.
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Old 08-24-2013, 12:38 PM   #47 (permalink)
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Testing

This is a great opportunity for all parties involved to discuss and dialog about these projectiles and paintballs in general. My opinions are just that, and they are derived from my experiences, conversations with firearms experts and performance testing. I will summarize the test that was performed; however, I will neglect product specifications and technical matter regarding our rifle and technology.

TEST PREPERATION:
Below is a list of the equipment and atmospheric conditions on the date of testing.

ATMOSPHERIC CONDITIONS:
Temperature: 84-86 Deg F
Skys: Partly cloudy
Wind speed: 3-5 mph
Wind direction: 9 o’clock
Humidity: 60%
Elevation: 845 ft
Elevation change between chronographs: < 6 inch

EQUIPMENT:
Chronographs: Competition Electronics light sensitive, Model # CE13800 Accuracy 1%
Rifle: SAR12 production model
Barrels: 16 inch Custom Products 2 piece barrel, 10,14,20 inch HH barrels
Light diffusers: 10x10 pop up tents
Linear Measurement: 150 ft tape measure
Elevation Change: Water level
Projectiles: FS rounds, Valkan Graffiti

TEST SETUP:
Fortunately we had the opportunity to set up our testing with a large woods at the 6 o’clock position and fully grown field corn to our 9 o’clock. Both of these natural structures benefited greatly in reduction of observed wind. We chose a 100 foot stretch of land that was relatively flat. We used a water level to inspect elevation change and found less than 6 inches of drop in the hundred feet. Six inches of drop in 100 feet is not optimal; however, for this particular test it was perceived to be a minor deviation.
We covered the shooting position and the 100 foot chronograph with 10x10 pop up tents, as the chronographs being exposed to direct sunlight created substantial errors. Once covered with diffused light we proceeded to shoot through both chronographs (One at a time) to verify correct measurements were being acquired.
We then proceeded to send rounds through the set of chronographs using the SAR12 with 20 inch rifled barrel. We sent a minimum of 20 rounds through the chronographs with the 20 inch barrel. An observation was made that the velocity drop was very consistent across the board. It was very common for the FS rounds to cross the second chronograph with a velocity of 220 fps. We didn’t measure each rounds mass! Final results were barrel velocity of 299-301 fps, and 218-222 fps at 100 feet. This gives us a BC of .0152 GA.
We then switched the rifle over to the Custom Products two piece 16 inch. Bore was very similar to HH20. Re adjusted the regulator to shoot 300 fps at the barrel. Sent another 20 rounds down range. Final numbers floated around 195 fps at 100 feet. This gives us a BC of .0115 GA.
Finally we decided to use the GA rather than G1 as G1 is based on more aggressive ogive designs. It has been expressed to me that the G1 modal is based on geometries that are exposed to supersonic flight. We went to the GA modal because the overall nose cross-section of pellets are in some examples very similar to the FS rounds. With exception to the waist design which is used to induce drag, thus stabilizing the round in smooth bore barrels. Very interesting article!


Finally my opinion about the Chronograph separation distance: I want to have the largest separation between chronographs because I want to find average BC values. The BC value probably decreases at range due to a slowing of the rotational velocity of the rounds. I am assuming that the spinning of the round from the barrel is reduced thus forcing the fins to create the spin from forward motion. This would then decrease at distance efficiency. I will be doing testing out to 100 yards to either prove or disprove my theory. I will be setting the at range chronograph at an angle parallel to projectile path and not parallel to earth surface. By doing this I eliminate the vector quantity that UV Halo is concerned.

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Old 11-08-2013, 12:44 PM   #48 (permalink)
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Great read.

Were Chicago's test results released?
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Old 11-09-2013, 10:11 AM   #49 (permalink)
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To be honest

I haven't preformed the tests yet. The boxes of first strikes are all down stairs still separated and labeled. I just got involved in things and completely forgot. May be if we have an Indian summer or if it's really cold, I'll reduce the sample rate by 50%. It just slipped my mind until I saw the latest post. You know how senile I am!
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Old 11-19-2013, 04:18 PM   #50 (permalink)
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I was running the numbers earlier and here are some things I noticed.
  1. The difference between G1 and GA is very small. Using the same base BC, (uv_halo's) G1 and the converted GA value produce practically identical trajectories - within the limitations of Chairgun, see below - and nearly identical maximum ranges. G1 peaks at 33 degrees (barrel angle) in the low 170s and GA peaks at 32 degrees in the slightly lower 170s.







  2. The difference between UV_Halo's and CarmatechEng's BC values is also very small, a paltry .002 and the graphs are essentially identical to the ones above. I would also add that the closeness of thier results says good things about their accuracy.

  3. Of the available drag curve profiles, (using the average of uv_halo and CarmatechEng) the G1/GA curve is the one most consistent with what real world testing we have. This curves sits at an estimated 173/171 yds, or 519/513 ft, which is very close to the 517 foot value that Mike of TechPB arrived at back in '09. So for right now, barring more testing or more precise max range values, this seems to be the curve that best models FS behavior. A list of final curve values:
    • G1, standard bullet - approx. 173 yds or 519 ft
    • GA, diablo pellet - approx. 171 yds or 513 ft
    • GL, round nosed flatbase lead bullet (my initial guess for best fit) - approx. 165 yds or 495 ft
    • RA4, .22 cal round nose flatbase (my second guess) - approx. 182 yds or 546 ft
    • GC, flat nosed cylinder - approx. 179 yds or 537 ft
A note on Chairgun: There seems to be a bug in Chairgun. The software wont allow us to plot trajectories past the internally calculated max range of the "End Range" function, which is 153 for G1 and 152 for GA. However, the Maximum Range applet calculates a noticeably higher (and more probable) maximum range value around the low 170s. So we dont actually know how the trajectory behaves between the 152 and 170s region. Whats more the Max. Range applet doesnt explicitly state the maximum range. We are frustratingly left to guesstimate the value from apexes and intersections. I sent an email to the software creator so hopefully well get some info or an update soon.

UPDATE: I busted out the image editor and went to work on the graphs using some measurement utilities, and as it turns out, the GA profile is a little closer to 517 than the G1. So for right now if you have to pick one for modeling behavior I would suggest the GA profile. Its superiority is small and tenuous but it is the better value at the moment.

Last edited by Whiskey Hammer; 11-19-2013 at 04:24 PM.
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