I've seen some conflicting views on the 140gr RDF with regards to the BC. What BC are the guys running them at distance using? Do we have any data from Bryan Litz on these projectiles? Thanks, BP
140 gr RDF actual BC numbers
- Thread starter BallisticPrimate
- Start date
Indeed there seems to be no middle ground with this projectile. They get glowing reviews from some quarters and then I read that the weights vary widely between projectiles. I've also seen a reported BC as high as .69 G1 - and then comments that the G7 BC of .330 is horribly overestimated. To top it off I'm also reading reports that the G7 BC of .330 is in fact conservative. I'd love to see a little science applied here so we can remove opinion from the equation and actually know what we're dealing with re the RDF's.
BC is affected by velocity. Since this projectile is being run (typically) from 2650fps, all the way up to 3200fps, it's expected that the BC numbers being reported are varying quite a bit...
I'm running them at a .340 BC from a 6.5 CM. I started at .330 but noticed my rounds were high at a 1210 yd target. This is after using the Magnetospeed and inputting all the data into my Ballistic calc. I adjusted my BC and made consistent impacts out to 1400 after that. My velocity was 2861 fps.
I've got almost 1000 down my 6.5 creed tube and .330 has been true for me. I am running them at 2740. If I remember later I'll update with the DSF (drop scale factor) for kestrel users. My elevation has been dead nuts out to 1320 and 1400 yards.
I am at 700 ft elevation if that makes any difference to anyone.
I am at 700 ft elevation if that makes any difference to anyone.
Sage advise and missed by many. A MV difference of 1-200 fps can certainly have an impact ( ha ha) on results and let's say an "equivalent" BC calculating factor....
Some ballistic apps let you set BC by velocity windows....a nice feature in my book.
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I bought some so I can at least comment on the claim that the weights are inconsistent. I weighed 20 on my RCBS Chargemaster scale and found an extreme spread of .1gr. For comparison the same exercise with 142smk's produced an ES of .2gr. So they get a pass mark there. I'll have more to report re BC numbers when I get a chance to take them out to 1000yds. It would be awesome to have Litz analyse these though.
How would one go about figuring out a true bc. I have a magneto speed and can read my mv. Could I shoot at 800 yards and then change my bc until my dope on my kestrel matches or is it more in depth than that?
I haven't bothered testing BC because I can't get them to shoot better than 1.5 MOA. How much jump are you guys using?
They awful for me at first. I'd been hearing .30 was standard jump for them. So I started at 20 and went to 35 in .005 increments. 20,25,30 were all bad. 35 shrunk right up so I layer did more up to .50 and 40 and 45 were sub 1/4 moa. I pulled the second shot on the last group to make it a fuzz over .5 moa but the other 4 measured .223 moa.
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