.25 Cal Ammo Shootout, Part I: Ballistics through Polygon Barrel ,BC's, etc...

[SMH77]

Beautiful mid-60’s weather here today so i plan to do a quick test of BC on just one .30 cal pellet to see how it changes over temp. Then I plan to convert to .25 LW (non-polygon) barrel and try to get all the data on the .25 cal pellets before I loose daylight. Hope the temp doesn’t drop and affect readings…

 

[Alejandroo]

"SMH77"Beautiful mid-60’s weather here today so i plan to do a quick test of BC on just one .30 cal pellet to see how it changes over temp. Then I plan to convert to .25 LW (non-polygon) barrel and try to get all the data on the .25 cal pellets before I loose daylight. Hope the temp doesn’t drop and affect readings…

Great, thanks again for all the hard work put into this

 

[SMH77]

Part II is complete and can be found here.

Sean

 

[SMH77]

Looks like I may have landed a second chrony now, so I can clock the same pellet through two distances. I'll need to confirm the readings are close enough to not worry about-assuming they are, this will cut my testing time in half, and give me data on a pellet - by - pellet basis.

Stay tuned...

 

[Groundhog]

Nice , I got my new crony in and was thinking of doing the same , still need to check the two against each other , but waiting for back ordered pellets . 

 

[Yrrah]

Edited out. H..

 

[SMH77]

Yrrah,

Please feel free to post the comparison of BC with distance and any/all related info here in this thread-I had hoped to spurn this sort of discussion that would be useful to all with these posts-and I really would like to see those charts too. I was looking back through the older posts on other forums and many of the images are not viewable any longer so I can’t gleen the data you have previously posted.

Thanks for alll you contribute!


Sean

 

[Yrrah]

OK Sean,
The original study was done in 2010 with data collected at 1.50 yd, 50 , 100 and 200 yd over a protected chronograph. I doubt anyone had previously shot an airgun over a chronograph at 200 yd or possibly 100 yards before.
This graph is a rudimentary summary showing average shot data at these ranges derived from the then new FX Kings, my very accurate BSA Bowkett Hornet; and interpolation and extrapolation as indicated.
The method and most relevant information about the study can be read in the reference below. Note that bc figures have been recorded as at the study altitude etc and also as standardised for perhaps useful comparison by others relative to their conditions.
Any claims made of course should be seen as being relevant in particular to the rifle and pellets used. There is some good discussion in the thread.

http://bsaog.co.uk/forum/index.php?topic=13228.

The graph: From 2010.

OK Chrome has decided to give up. I will try Firefox. Good that graph is up now.
Hope any who read the research report will find it interesting as that is pretty much where the topic of bc and range/velocity all started. I do have LabRadar data to support it now. Perhaps someone can copy the full report and paste it in here or in a new thread? The pics in the thread won't show either as Photobucket will not allow them to be posted now. Technology !!
Kind regards, Harry.

 

[Groundhog]

Finally had a chance to compare the chronographs and found them to be within 1 fps across 10 shots .

Then set up and did a quick string with the Crown shooting King Heavy Mk2 at 880 with 76 yards between the chronos and got a BC of 0.0515 . Looking forward to doing the 50 yard test the same way SMH77 did to see the difference that the seperation between chronys makes . Now if JSB will get us some pellets I'll get on with it , almost out .