Sierra GameChanger Impact Velocities

S

steve4102

New member
I worked up a load with 130gr Sierra GameChanger in my 6.5 PRC.

MV is 3250fps.

I asked you guys if that was to fast for this bullet inside 200 yards. I was told to contact Sierra and ask them, "It's as simple as that"

I called them and was told " no problem" , that bullet will do fine.

I tested this round at 100 yards shooting into water jugs. I know water isn't the best, but it's all I had.

The bullet exploded at the first jug and never penetrated the second jug.

I sent Sierra an email asking again, as I wanted their reply in writing.

Here is their reply.

Duane Siercks<duane@sierrabullets.com>








To:​
You
​
Fri 7/12/2024 10:35 AM
Steve, we do not see that velocity being an issue on deer sized game.

Duane Siercks
Consumer Service Manager
Sierra University Instructor
Sierra Bullets, LLC 1400 West Henry St. Sedalia, MO. 65301
Phone#: (660)827-6300 Ext. 572  Toll Free: (800)223-8799
Fax: (660)827-4999
duane@sierrabullets.com  

So much for contacting the manufacturer " it's as simple as that".
 
When you shoot water jugs in a line, the first one will rupture and push the other bottles, and not in a straight line. I have shot 9mm hollowpoints and that is exactly what happened. The first jug is DRT and I do not think your exercise is a guage of rifle bullet effectiveness. What Sierra told you is "no issues". I think they are correct.
You could shoot into ballistic gelatin, with a
layer of denim, and throw some bones into the gelatin (pour the gelatin over the bones in the mold).
https://www.midwayusa.com/product/1020533260?pid=770762
You will see a different result.
 
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Well, you've answered your own question, haven't you. Sierra sells two 7mm 160 gr bullets. The hollow point, according to their manual, has a thicker jacket designed for magnum velocities. That's one, along with the Nosler Accubond, that I load in 7 Mag. I think that GameChanger is basically a good 'ole SGK with a polymer tip. Pretty good bullet, but for my "new to me" 264 Win Mag, I'm counting on the Barnes 127 LRX. I've had good luck with Swift A-Frames as well.
 
i also wonder what affect rotational velocity has on terminal ballistics. the 6.5 prc is kinda high twist rate isn't it? if the same projectile turning 66% the rpm would it have the same terminal results?

i don't recall ever seeing that tested.
 
What are you planning on hunting? If deer, then that bullet will be fine. If Elk, then I'd want a lot more info cause I'm not a fan of 6.5 anything on large animals.
 
i also wonder what affect rotational velocity has on terminal ballistics.
Click to expand...

The twist rate establishes the rate of rotation, in terms of distance traveled. 1 turn in X inches. The distance traveled determines the number of revolutions, and the velocity determines the amount of time to cover the distance.

These things are known and taken into account by the people who design and make bullets.

IF a given twist rate "overstabilzes" a bullet, or causes so much rotational force that the bullet comes apart, you are using the wrong bullet for that twist rate.

That's not on the bullet maker, that on you, for choosing what you did.
 
Cup and core bullets come apart at impact velocities of 3000fps. Went to Grand Slam and Interbonds several years ago and no more ruined meat.
 
Take your bullet diameter and divide it by the rifling pitch in inches. The resulting fraction is how much slower the rotational surface speed is than the bullet's forward velocity at the muzzle. Usually, it is slower enough not to affect terminal performance adversely. On the other extreme, if you have a slow twist that just barely stabilizes the bullet, you are much more likely to get the bullet tumbling in the target. That can enhance stopping power.
 
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