Velocity Limit To Be Shown On Bullet Boxes

[ThunderDownUnder]

I recently bought some Sierra MKs in 224, 90 grain caliber. I checked the manufacturers website and the bullet data and then started testing some loads. I was them informed in numerous threads discussing this bullet that it would come apart at velocities above 2650fps.

I was looking to drive this bullet at velocities of around 2950fps so I contacted Sierra. Duane Sierks from Sierra confirmed that the bullet was in fact limited to 2650fps. I'm thankful for the honesty of Sierra in providing me with a direct answer.

This then raises the issue of manufacturers providing bullet data like velocity limits on their boxes so the customers can make an informed choice on purchasing them.

Most of us would not have a clue as to what velocity a bullet is good for as this is something the manufacturer tests. What do you think about bullet specs being printed on the labels of the boxes? Its a problem in calibers where the expectation is for high velocity and the bullet falls short but no information about the limitation is available.

I work in the electronic/electrical industry and even a 10c diode has a data sheet with its specs available. Maybe its time to expect a little more info from bullet manufacturers.

Ian

 

[msnations]

I've heard the same thing about SMK 90s but at the same time I've seen them pushed much faster (3000 FPS) with 0% losses. I would think that a problem with testing for bullet failure is the variability amongst barrels. Load data and published pressures are 'reasonable' approximations for any given barrel, but maximum RPM given some bullet is probably much more variable. Heck, some barrels seem to blow everything up...

 

[medicineman]

Losing bullets at that low velocity is caused by the 6.5" twist that is reccommended. The 90's will stabilize in a slower twist. I've pushed them to 3500 fps. in a 1-8" twist, and only lost a few due to hot weather(101 in the shade).
There are several factors that will cause a bullet to explode, and after conversing with Rich Macholtz, one of the combinations was a 1- 6.5" twist coupled with a 3 groove barrel.....bullets would come apart at 2550 fps.
The edge of the land is what twists the bullet, and with 3 edges versus 6, there is more torque on each edge and it tends to disrupt the jacket, especially with a radically fast twist.

I used a 6 groove barrel with no problems.