Recently I posted a topic regarding the temperature effects on the external ballistics of JSB Heavy, MK I pellets through my primary gun (RAW HM1000x with a LW Polygonal barrel). In the results, I had an entry listed showing the effect of the same gun, with a different barrel (LW tradtionally rifled barrel) which showed different external ballistics results-markedly so. Naturally, as we're all interested in learning together, this sparked some healthy discussion as to whether the results were 'real' or not so I set out to find out for sure. In the original thread, I suspected they were real, but the environmental conditions were slightly different so there was some doubt that was easiest to settle simply by running some data...
Once I compiled the results, the results showed very clear differences-more on that to come. As such, I though there would be enough interest in this topic to split if off and make it more visible to the whole community as a reference (like I've been doing for other testing I've done).
Objective:
To compare the external ballistics results from 3 different barrels, using the same pellets, in the same atmospheric conditions to determine if there are significant differences between the resulting external ballistics of the pellets.
Contestants:
FX WildCat Mk II .25 cal with Factory SmoothTwist barrel, Huma Reg (set to 150 bar), and hammer spring adjusted to yield ~ 55 fpe.
RAW HM1000x in .25 cal with factory polygonal barrel (made by LW), and .25 cal factory 'rifled barrel' (also made by LW). Hammer spring basically set to its lowest position (shooting ~ 60 fpe).
Method:
Measure the velocity of two common pellets at 1 yard and 50 yards, averaged over a string of 12 shots, compile the results and calculate the BC of each combination. I use Chairgun Pro (desktop version) for the calculation of BC and use the GA form factor for diabolo pellets. I capture the data using two Caldwell chronographs (that have been calibrated to each other) and then compile the results in Excel. I record the local weather conditions using my Accuweather app-but only as a double check of the weather conditions the Caldwell app pulls in from its source (not sure where-but they match pretty closely). I do use the average humidity over the shooting session and look for any changes in pressure or temperature during the session-and then use the averge value of those numbers (from the Caldwell numbers).
At yard: (Distance is set from the end of the moderator to the center of the rearmost sensor window)
At 50 yards: (distance is set via Nikon laser rangefinder to target)
Summary of Results:
All data shown below represents the same gun configuration for all testing tonight: meaning the hammer spring and regulator settings unchanged from setup to setup.
Order of data acquisition:
RAW with polygon barrel, shooting JSB MK I pellets first, then MK II pellets
RAW with LW rifled barrel, shooting JSB MK I pellets first, then MK II pellets
Wildcat Mk II with ST barrel, shooting JSB MK II pellets first (mag were already loaded), then Mk I pellets
Data:
Conclusion(s):
Yes, the barrel does indeed have a pretty profound effect on the external ballistics of the pellets. From the chart, it's easy to see that the LW rifled barrel is on par with the FX SmoothTwist barrel. The LW polygon barrel shows about a 15% advantage over the other two barrels.
Notes:
Please ask if you have any questions and feel free to point out anything I missed.
Sean
I hope you find this info helpful? Is so, please consider taking a second and simply leaving a '+' with a nice comment for me-it let's me know my time and effort is appreciated and keeps me going with this kind of work for the community. I've spent a bunch of money on Chronographs now, lead and time so it's a pretty small way of saying 'thanks for the efforts'. Enough said- Enjoy!
Once I compiled the results, the results showed very clear differences-more on that to come. As such, I though there would be enough interest in this topic to split if off and make it more visible to the whole community as a reference (like I've been doing for other testing I've done).
Objective:
To compare the external ballistics results from 3 different barrels, using the same pellets, in the same atmospheric conditions to determine if there are significant differences between the resulting external ballistics of the pellets.
Contestants:
FX WildCat Mk II .25 cal with Factory SmoothTwist barrel, Huma Reg (set to 150 bar), and hammer spring adjusted to yield ~ 55 fpe.
RAW HM1000x in .25 cal with factory polygonal barrel (made by LW), and .25 cal factory 'rifled barrel' (also made by LW). Hammer spring basically set to its lowest position (shooting ~ 60 fpe).
Method:
Measure the velocity of two common pellets at 1 yard and 50 yards, averaged over a string of 12 shots, compile the results and calculate the BC of each combination. I use Chairgun Pro (desktop version) for the calculation of BC and use the GA form factor for diabolo pellets. I capture the data using two Caldwell chronographs (that have been calibrated to each other) and then compile the results in Excel. I record the local weather conditions using my Accuweather app-but only as a double check of the weather conditions the Caldwell app pulls in from its source (not sure where-but they match pretty closely). I do use the average humidity over the shooting session and look for any changes in pressure or temperature during the session-and then use the averge value of those numbers (from the Caldwell numbers).
At yard: (Distance is set from the end of the moderator to the center of the rearmost sensor window)
At 50 yards: (distance is set via Nikon laser rangefinder to target)
Summary of Results:
All data shown below represents the same gun configuration for all testing tonight: meaning the hammer spring and regulator settings unchanged from setup to setup.
Order of data acquisition:
RAW with polygon barrel, shooting JSB MK I pellets first, then MK II pellets
RAW with LW rifled barrel, shooting JSB MK I pellets first, then MK II pellets
Wildcat Mk II with ST barrel, shooting JSB MK II pellets first (mag were already loaded), then Mk I pellets
Data:
Conclusion(s):
Yes, the barrel does indeed have a pretty profound effect on the external ballistics of the pellets. From the chart, it's easy to see that the LW rifled barrel is on par with the FX SmoothTwist barrel. The LW polygon barrel shows about a 15% advantage over the other two barrels.
Notes:
- The same pellet probe was used for the polygon barrel and rifled barrel. Since the gun went back to RAW about a year ago to get converted from the 50 fpe version (LW rifled barrel) to the higher powered 60 fpe version (polygon barrel), the probe depth is currently optimized for the polygon barrel
- The pellets seated noticeably more difficult into the throat of the rifled barrel.
- A single shot tray was used for all RAW shots
- The factory magazine was used for the FX shots
- This is the first test that I've done that show the BC of the MK II pellets is slightly higher than the Mk I pellet. Every test before showed the Mk I version is slightly better in the polygon barrel.
- My son primarily shoots the Mk II in his FX. Perhaps I should have him spend some time with the Mk I pellets to see if those shoot better? They loaded in the magazine just fine.
Please ask if you have any questions and feel free to point out anything I missed.
Sean
I hope you find this info helpful? Is so, please consider taking a second and simply leaving a '+' with a nice comment for me-it let's me know my time and effort is appreciated and keeps me going with this kind of work for the community. I've spent a bunch of money on Chronographs now, lead and time so it's a pretty small way of saying 'thanks for the efforts'. Enough said- Enjoy!
