Written by Ballistic Technician Philip Mahin
It was my understanding that Sierra’s 90gr HPBT GameKing #1615 was going to be the greatest thing since sliced bread in a 257 Roberts, and boy was that a correct statement!
I was finally able to purchase a limited run Ruger 77 Hawkeye chambered in the 257 Roberts cartridge. The factory walnut stock is shaped to fit me like a glove so it points easy and the trigger is clean. This makes it an easy shooter and is more than likely the reason it has shown me the accuracy it has. The 4-12×40 scope is mounted as low as it can be without touching the barrel and has a simple duplex reticle, just like I like a hunting gun to have.
It wasn’t going to be long before the 2017 deer season would be upon me so I had to work fast and find a combination it liked. We offer many bullets in the 0.257” diameter that can be used for hunting and since whitetail was on the menu, I decided to stay with our 100gr bullets or lighter. In my ladder testing, our #1615 90gr HPBT GameKing was an exceptional choice and it showed a preference to RE-15 powder. The charge it liked was only producing 2,900fps but the extreme spread was next to nothing and sometimes producing duplicated velocities for the first two shots from a cold barrel. By the way, those first two shots always touched at 100 yards and always right where the scope said they should be.
I’ll save the rest of the accuracy reports and scope set up for another post but for now, I’ll share how the bullet performed on impact. I didn’t have time to make any reduced loads (for expansion at distance information) so I set up jugs at 100 yards and shot what I had. My calculations show this bullet impacted at 2,550fps and it has 52 grains (around 58%) left. I found it in the third jug so it stopped within eighteen inches of penetration and of the three, it was the only one that wasn’t completely obliterated. If I would have made contact with a whitetail in that initial outing, it would have proven to be extremely effective on a broadside shot. This is also going to be my go to coyote gun when it comes time for that so I may have other reports to share in the future.
Till then, be safe and enjoy your shooting.