GS 177 early test

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Michael Eichele, Jan 25, 2012.

  1. Michael Eichele

    Michael Eichele Well-Known Member

    Jan 6, 2003

    The last couple of days at the range I tested a few GS 30 cal 177's. I only have an 11 twist barrel on my 308 and both GS and stability calculators recommend at least a 10 twist barrel. The stability calculators show that the 11x is about 1.0 +/- so I thought I would at least shoot one to see if it would punch the target straight or sideways. Two days ago it was 15 degrees and my range is less than 100 feet above sea level so the air was very dense and she punched nearly a straight hole. There was a detectable amount of yaw. So I decided yesterday to shoot a couple of groups. It was -5 degrees this time. While the groups were decent, there was quite a bit more yaw. These are on such the ragged edge of stability that 20 degrees of difference made a difference in how much they yawed. Even with this amount of yawing, the first group of 45.0 of VV N540 was 1 MOA and the second group using 45.5 of N540 printed 0.5 MOA. If they are just yawing a bit in 15 degree sea level air, hopefully they will perform well at higher altitudes and warmer air such as when and where I hunt dall's, lope and coues bucks.

    I am taking a few of these to Arizona this week and will shoot them this weekend at 5000' in 60 degree air. If all goes well, these maybe my dall sheep load this year to see how they do on game. Assuming I can find a ram I want to shoot! According to the stability calculator, they should be 1.3 at 5000' and 60 degrees.

    I seriously doubt the BC is anywhere near what GS says they are but that remains to be seen. Hopefully, this weekend I can squeeze in a double chrony test. Whatever the results, I wouldn't put too much stock into the test since they are not on the best side of the stability factor. My guess is that with more stability, they would be between .550 and .575. Just a guess. These have an amazing form factor but the sectional density in not nearly high enough for it to be .638 like GS claims. We'll see....