.25 Cal Barrel Shootout: Ext BC's of FX WC-II ST, RAW Polygon, & RAW LW Rifled

Forums Pellets, Projectiles, & Ammo .25 Cal Barrel Shootout: Ext BC's of FX WC-II ST, RAW Polygon, & RAW LW Rifled

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    SMH77
    Participant
    Member

    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:

    • 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!

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    Glem.Chally
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    Member

    Great work and well put together!  I have a ST as well and I find the MK1 do fit into the breech a bit tight and are a bit slower in my findings, I am finally receiving my .22 LW poly unchoked barrel blank shortly looking forward to giving that a rip.  Interesting to see the increase in BC using it from your experiments.

    The 60fpe version of your RAW you say the HST is basically at the lowest setting?  At what reg pressure?  What does it sling them at when turned up?

    Again great work Sean,  hows your son liking the WC?

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    SMH77
    Participant
    Member

    Glem.Chally

    Great work and well put together!  I have a ST as well and I find the MK1 do fit into the breech a bit tight and are a bit slower in my findings, I am finally receiving my .22 LW poly unchoked barrel blank shortly looking forward to giving that a rip.  Interesting to see the increase in BC using it from your experiments.

    The 60fpe version of your RAW you say the HST is basically at the lowest setting?  At what reg pressure?  What does it sling them at when turned up?

    Again great work Sean,  hows your son liking the WC?

    Thanks GC!  My son LOVES the WC-and that is important, because he wants to get out and shoot (rather than being on that stinkin phone, grrr…).  

    Funny that you ask about turning up the HST-I just checked that the other day (finally) and got my answer: at 79F it was shooting about 945 fps at the muzzle, for about 66.5 fpe.  This is without messing with the regulator at all-which I think is set at about 145-150 bar, based on watching the velocity results and listening to the change in sound.  Interestingly enough: at the higher speeds, my BC went down from where it is at tonight.  I'm assuming that is because of the aerodynamics that happen as the speed approaches the sound barrier, but am not sure.  

    I will be interested to hear back when you have had a chance to get to know your polygon barrel setup.  I do not know if mine is choked or not, so I'm not sure if my results are indicative of what you can expect.

    Sean

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    stoti
    Participant
    Member

    Great information! I really enjoy your testing and the breakdown of information. Keep up the great work! Stoti

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    Kim
    Participant
    Member

    Nice work!

    Also interesting that the poly barrel seemed better than the rifled.  Not only was BC higher (which makes sense as polys are supposed to gall the pellet rims less than rifling), but also the variance in velocity (ES, SD, etc) was lower at 50yd.

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    SMH77
    Participant
    Member

    Yeah, one other point too that isn't obvious in the data above (but is to me, because I've been watching the DB data I've been generating): the BC's from the poly barrel actually were a little lower last night than in the weeks past.  Recently I finally turned up the hammer spring tension to see what would happen to the power output and BC, etc at the highest setting (results are posted in my reply above, in this thread).  Interestingly, the BC dropped considerably for the poly barrel setup.  

    Background: when Martin was working on the high power version of the .25 cal, we were emailing back and forth initially.  At that time, he had the setup running really hot (68 fpe ~ 950 fps with the heavies) and was getting very good results at 100 yards.  I was interested and later ordered the setup. When I ordered, he was intent on setting the velocity closer to 900 fps instead (and had actually forgotten that he told me that he had it running up at 68 fpe).  I finally got to the reason: at the high power / speeds, the poly barrel leaded up super fast-like within 100 shorts or less fast.  He deemed this unacceptable.

    Fast forward to when I turned up the power on my polygon setup: I haven't cleaned the barrel in quite a while (been running in the upper 800's to about 910 fps, depending on temp-see other thread).  I'm wondering if the drop in my BC is actually an indication of leading up in the barrel? I'm thinking about doing a BC test pre/post cleaning to see if anything shows up in a change to the BC as a result?  

    Just some thoughts I'm sharing out loud…

     

    Sean

     

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    Hynzie
    Participant
    Member

    as always SEAN your break down and reports are excellently done ,well worded and really nice reading ,the info created and the time you spend ,its appreciated  HYNZIE

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    nomojo65
    Participant
    Member

    Good luck guys!

    • This reply was modified 6 days ago by nomojo65.
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