300 Winchester chrony results

[303carbine]

Rifle--Remington 700 BDL 300 Winchester
Bullet--190 grain Hornady BTSP....(Thanks ,Win Shooter)
Powder--70 grains IMR 4831
Federal magnum primers
Winchester brass
Velocity....2930 fps

The big surprise was when the Hornady 190 grain BTSP chronographed faster than the 180 Hornady SP with the same load of 70 grains IMR 4831, anyone have any ideas why this happens??

 

[chappy]

the bullet is very sleek with not a lot of bearing surface. less resistance more speed.

 

[Gatehouse]

The big surprise was when the Hornady 190 grain BTSP chronographed faster than the 180 Hornady SP with the same load of 70 grains IMR 4831, anyone have any ideas why this happens??

More pressure.

 

[Noel]

More pressure.

X2

Slightly heavier,longer bullet= more bearing surface which makes more pressure.
Not every time but most times.

Getting magnumitis are we?

 

[agent_mango]

Also keep in mind that the max amount of safe powder charge goes down as the bullet weight goes up. So keeping the same powder charge for the heavier bullet meant the heavier bullet got a relatively stronger charge.

 

[303carbine]

Also keep in mind that the max amount of safe powder charge goes down as the bullet weight goes up. So keeping the same powder charge for the heavier bullet meant the heavier bullet got a relatively stronger charge.

It's still below the book max by 3 grains, this rifle reaches peak pressure faster I guess.That's why I always start lower and work up watching for any sign of pressure.

 

[303carbine]

X2

Slightly heavier,longer bullet= more bearing surface which makes more pressure.
Not every time but most times.

Getting magnumitis are we?

I caught magnumitus way back about 1973 when I got my first 350 Remington mag in the short Mohawk rifle.....
By the way, I think the 190 BTSP has less bearing surface than the 180 flatbase.....I may be wrong,it's happened before!!!