7mm Bob's Boattail from NOE has a BC of 0.26

[rsterne]

The difference between a RN (.22LR) and a FN (with Meplat), right, Miles?....

Bob

[ballisticboy]

Yes Bob. Sorry, I did not realize I had forgotten to reply.

[Scotchmo]

Today, an airgun shooting the 7mm Bob’s Boat Tail from NOE beat out all others at the 2023 RMAC Magnun airgun slug match:

https://competitions.ultimateballistics.com/competitions/54/rankings

[rsterne]

WAY TO GO, SCOTT !!!!

Bob

[Scotchmo]

WAY TO GO, SCOTT !!!!

Bob

I was shooting sorted 7mm flat point BBT slugs in the 106gr to 106.6gr range. At 1055fps using a RA4 0.220 BC.

[rsterne]

Just to give an example of why the G1 drag model is not suitable.... If we convert the BC(RA4) = 0.22 at 1055 fps to G1, we get BC (G1) = 0.289....   

Using that will give incorrect results for drop and windage....

Bob

[Scotchmo]

Just to give an example of why the G1 drag model is not suitable.... If we convert the BC(RA4) = 0.22 at 1055 fps to G1, we get BC (G1) = 0.289....   

Using that will give incorrect results for drop and windage....

Bob

The only way that I have been able to get satisfactory G1 POI predictions with these boat tail slugs at high velocity/long range is to use the multi BC function. RA4 is a better (though not perfect) match for this slug. At least out to the 300 to 350 yard range. I have been doing OK with a fixed RA4 BC.