.25 Cal Ammo Shootout, Part II: Ballistics through LW Rifled Barrel ,BC's etc...

In follow up to my 'Part I' post, I have now tested 4 of the same 6 pellets through my 'traditionally rifled' Lothar Walther (LW) barrel and compiled the data for myself, and I figured I’d share with you the results of my measurement of the 4 pellets with you to help the airgun community. The following pellets were tested in .25 caliber, as shot through my RAW HM1000x, LW barrel (traditionally rifled): the JSB lites (25.39 grain), the JSB Heavy, Mk I (33.95 grn), the JSB Heavy, Mk II (33.95 grn), the H&N Baracudas (31.02 grn). In part I, I also tested the H&N Baracudas Hunter Extremes (28.40 grn), and the Predator Polymags (26 grn) pellets, but did not have sufficient daylight to complete testing those pellet the other day. If you desire me to test those pellets, please let me know and I'll put it on my 'to-do' list for when temps and conditions were similar to the 4 pellets tested here.

All pellets were not measured and were taken straight out of the tin without sorting for weight. No sorting for head sizes was complete either-so accuracy and variability are what you will typically experience shooting straight out of the tin.

1524359500_20667710305adbe14c512874.96565428_IMG_3893.jpg


Muzzle velocity, near was taken with the rear window of the chrony at 1 yard from the tip of the moderator
Distance to far measurement, was taken with the rear window of the chrony at 50 yard from the tip of the moderator
Delta (distance) between locations: 49 yards (measured with a Nikon laser rangefinder with angle compensation)

Setup​ @ 1 yard:
1524359544_20056537135adbe1787281a8.79422202_IMG_3865.jpg
 
1524359557_249359255adbe1850d2132.49764435_IMG_3867.jpg


Setup at the target (@ 50 yards, a 49 yard delta):
1524359586_20263582375adbe1a28779d9.17856570_IMG_3880.jpg


I opened up Chairgun (Mac version) and adjusted the environmental conditions, altitude, etc. I then went to the BC calculator app, plugged in the data, and calculated the following results (below). The average temp today was 63F, with calm, but low winds (9 mph out of the NNE), 48% Humidity, pressure at 29.98 in Hg.

My gun: RAW HM1000x, setup in .25 caliber, with a LW traditionally-rifled barrel. Notes: the same chrony was used at both distances (as in the same exact serial number). Velocity data is shown below. I shot a full magazine's worth of pellets (though single-shot loaded) with the chrony set at both the near and far locations, with each pellet (so 12 shots for each x 8 setups = a LOT of shots). The one exception was the last shot on the H&N Baracuda's at 50 yards-I ran out of daylight and absolutely could not squeeze out one more single reading to complete the data-yep, it pissed me off, grrrr... LOL. :D

Note: the temperature was different today compared to when I shot 'part I' through the polygon barrel, so the first step in performing part II was to shoot a single, common pellet through the same setup to determine the effect of the temp on the BC's. I did this with the .30 cal setup (was already setup) shooting the JSB lite pellet. From 48F to 66F, the temp effect resulted in a rise of approx 7.6% in the BC. Thus below, I've added both the RAW data (at the tested temp) and the temp corrected BC's for better 'direct comparison' between the barrels-because I know that's ultimately the comparison that will happen. Just be aware, there are changes from barrel to barrel, as well as with changes in environmental conditions (temp, humidity, etc). BC also changes between distances that are tested-hence the need to settle in on a single, repeatable test method (which I'm in the process of writing up for anyone to perform similar testing with their own combinations).

A few comments: don't read too much into the standard deviations of the less accurate pellets (JSB Lites, H&N BHE, and PP) at 50 yards. I had several 'err1' or 'err2' messages as the pellets drifted slightly left or right, not centering over the optical windows. I feel this affected the reading slightly on certain pellets-thus I had to reshoot several of the pellets to get a full 12 shots of data. To be as accurate with the numbers as possible, I threw out the high and low (for calculating the averages) for both the 1 yard and 50 yard data. The standard deviation and spreads shown in the chart below represent all 12 data points for each pellet, at each distance-not the middle 10.

I hope this is helpful information for anyone looking for data from this gun / setup? If so, and you appreciate the time / effort, please take a minute and leave me a ‘+’ (it’s just a small way that makes me feel like I’m helping contribute useful content to the forums), and consider posting a reply as well. It's a small thing, but it's a big thing to me to know my efforts are appreciated, and keeps me motivated to spend time doing this stuff for the community.


First up: JSB lites (25.39 grn):

1524799139_10655718275ae296a3ef63d0.00776098_25 Cal BC - JSB Lites 25.39 grn-LW Rifled.jpg


12 shot group:

1524767863_21034016185ae21c7775d074.45838755_B7157FAC-A99A-4774-8D81-A38A4EA3969E.jpeg


Next up: JSB Heavy, Mk I (33.95 grn):

1524799158_9748421525ae296b63130b9.68372929_25 Cal BC - JSB Heavies, Mk I 33.95-LW Rifled grn.jpg


12 shot group:

1524767918_10261723205ae21cae8c2e05.91423169_64861D4D-518B-4535-8F42-B041A72E2394.jpeg


Next up: JSB Heavy, Mk II (33.95 grn):

1524799179_14575442985ae296cb371dd3.56036262_25 Cal BC - JSB Heavies, Mk II 33.95-LW Rifled grn.jpg


12 shot group: (note the shots at the bottom are from the JSB Lites)

1524768008_16298697165ae21d08ecd357.80012030_C24ADB21-6C3D-4586-84CB-4F5D8C34BB69.jpeg


Next up: H&N Baracuda (31.02 grn):

1524799203_1285369535ae296e37ff079.18946159_25 Cal BC - H&N Baracuda 31.02-LW Rifled.jpg


12 shot group:

1524768116_14910747485ae21d747e7912.20662590_831E293C-BF6C-4B19-B634-1F677F65A907.jpeg


Next up: H&N Baracuda Hunter Extremes (28.40 grn):

(Not tested through LW rifled barrel.)

12 shot group:

(Not tested through LW rifled barrel.)

Last up: Predator Polymags (26 grn):

(Not tested through LW rifled barrel.)

12 shot group:

(Not tested through LW rifled barrel.)

And the RAW data, summarized in chart form (pun intended, LOL):

1524771840_9670222275ae22c002b13c5.93152086_EAB881AA-B0B7-487F-9BEE-29B9B5FE084C.png


Overall comparison of the groups:

Top Group: JSB Heavy, Mk I (Note flyer low right, and high left -those were the first two shots)
Second Group: JSB Heavy, Mk II (Note: some of the JSB Lites from the group below crowd this group)
Third Group: JSB Lites
Bottom Group: H&N Baracuda (they shot pretty well in this barrel-I was impressed!)

1524769893_20656016965ae22465997c52.24595205_B9BF7387-8ADC-4307-8F97-E6CC0E329F2E.jpeg


Overall comparison of the barrel effects on the BC’s:

1524769785_3103599005ae223f92eedb0.53406540_11719872-8CCF-4E76-96DF-33B4EBE52BB3.png



Sean 

PS: as a side note, several people have asked about the app to measure group sizes: the (iPhone) app is called 'SubMOA'. It's a manual process, and a little clunky at first, but it ends up being decent to use once you get the hang of it...
 
Thanks. Amazing how much better the BC is for the LW Poly barrel compared to the standard rifled LW barrel! Why do you think that is?
​When you say "same chrony was used", does that mean you shot muzzle then target speeds separately, or do you have two of the same chrony make and model...?
​Your data shows the exact same MOA group size for Poly and standard LW...? 
 
"Centercut"Thanks. Amazing how much better the BC is for the LW Poly barrel compared to the standard rifled LW barrel! Why do you think that is?
​When you say "same chrony was used", does that mean you shot muzzle then target speeds separately, or do you have two of the same chrony make and model...?
I added a chart directly comparing the barrels as that will save time jumping between web pages...

My guess is that the smooth transitions with the polygon (basically a polygon shape, with rounds at each corner-thus no cut groove) create less drag profile on the pellets while traveling down the barrel-and that equates to better aerodynamic drag on the pellet as it travels through the air? My educated speculation only...

By same Chrony, I mean same serial number unit (Edit: I added a note for better clarity above): had to shoot at 1 yard to collect ‘near data’ and then move to target and collect ‘far data’. This is something to note too: since I am testing some during ‘warming up hours’ (polygon barrel) and others at cooling down hours (LW rifled barrel), the temp while collecting data at the far target may be more affected by being warmer at the muzzle (first) and then the temp colong down when shot near the target (second) and vice versa. Granted, it is only a few degrees, but it is there, and does affect the data. I can’t do anything about that since I am testing outdoors and not in a controlled tunnel. This shift would favor (slightly) the polygon barrel. This was NOT intentional, but a result of testing late morning on Sat for the polygon barrel, vs after worl for the LW rifled barrel.
 
My guess is that the smooth transitions with the polygon (basically a polygon shape, with rounds at each corner-thus no cut groove) create less drag profile on the pellets while traveling down the barrel-and that equates to better aerodynamic drag on the pellet as it travels through the air? My educated speculation only...
Just to add more "educated speculation only...", it's kind of the same effect that produces the FX Smooth Twist barrels on pellets if you look through one FX barrel you can see the polygon shape, the difference is that the LW Poly has full rifling not a few inches at the end of the muzzle like FXs, and as many people say the ST barrels output better BCs for any given pellet.
One question crossed my mind reading all this, would it be better or more thorough methodology to compare if there's any differences in BCs calculating between velocity change like you did and POI change let's say at 50 yards second zero and 80 yards (I think at this ranges is where you start to see more pellet drop). Maybe I can do that tests as complementary info of course, what do you guys think ??

Alejandro

 
"Alejandroo"
My guess is that the smooth transitions with the polygon (basically a polygon shape, with rounds at each corner-thus no cut groove) create less drag profile on the pellets while traveling down the barrel-and that equates to better aerodynamic drag on the pellet as it travels through the air? My educated speculation only...
Just to add more "educated speculation only...", it's kind of the same effect that produces the FX Smooth Twist barrels on pellets if you look through one FX barrel you can see the polygon shape, the difference is that the LW Poly has full rifling not a few inches at the end of the muzzle like FXs, and as many people say the ST barrels output better BCs for any given pellet.
One question crossed my mind reading all this, would it be better or more thorough methodology to compare if there's any differences in BCs calculating between velocity change like you did and POI change let's say at 50 yards second zero and 80 yards (I think at this ranges is where you start to see more pellet drop). Maybe I can do that tests as complementary info of course, what do you guys think ??
Alejandro

A couple of comments: from what I have seen, the FX ST barrels (for whatever reason-I don't know) seem to all have lower BC figures that a traditional LW, or LW Polygon barrel. For instance, compare either of my findings to the results from the HAM database in the sticky (note: that's hard to compare directly because the LabRadar results only go out to 30 yards, which results in a lower BC number than tested out to 50 yards.). Perhaps someone can follow my methodology from 1 to 50 yards once I get it posted and we can see for real how they actually compare-otherwise it could end up in arguing without any data-so take my comment about the lower BC's from FX barrels very, very lightly until we can prove/disprove that observation...

Regarding testing over longer distances: I think, in reading a BUNCH of Harry's posts (Yrrah) on the yellow forum, that he's already concluded testing out to longer distances results in higher BC numbers reported. Thus, if you tested from 1 yard to 75 yards, the numbers for each pellet should be even higher than I've shown in my results. I could do a quick test to confirm that finding of his, but I believe him (someone correct me if I'm wrong...).

Regarding using POI changes: I honestly don't think it's nearly as accurate as using a chrony-simply because there's too much that can affect the group size, and location (a headwind starts, for example, will generally push your group lower, etc). I think its best to try to wait for calm conditions, and just use a Chronograph.

Having said that, I'm all for learning if someone wants to test and post their findings here...
 
Update: I added all the screen shots above to show the BC calc's from the Mac version of Chairgun. I also added descriptions to clarify which group is which on the full sheet view. The lone flyer on the lower leve was from sighting in the scope after swapping calibers: literally that single shot (aimed at the lowest, right most target) was all I took, then read the adjustment from the reticle and started shooting my groups for the test. I probably could have dialed in another .2 MIL to the right, but it was close enough for me....

The info should all be there now.


Sean
 
"SMH77"
PS: as a side note, several people have asked about the app to measure group sizes: the (iPhone) app is called 'SubMOA'. It's a manual process, and a little clunky at first, but it ends up being decent to use once you get the hang of it...

So based on this and the fact that I use an android phone I did a little searching there is an equivalent in android called Range Buddy

I just did a sample of a 25 meter group from my 30 cal LRT and here is the result for comparison.
Not trying to hijack here Sean, just adding an option for Android users.
 
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great stuff.. looking for more comparisions between the reg lw and poly barrels.

so in general the lw rilflieng has a higer bc than the poly ? but the poly drifts in the wind do you find this to be true?

No, the data that I have shows the opposite: the LW rifled has a considerably lower BC than the LW Polygon barrel. The higher BC out of the polygon barrel thus makes the pellets coming out of the polygon barrel lose less velocity over distance and be less affected by the wind. In these regards, the LW rifled barrel performs worse.

Hope that helps clear it up?



Sean