Sendero .300 ultra
Picked up a Sendero .300 Ultra Mag and can't find the barrel twist. Anybody know? Also need to figure out a really accurate hunting load, want a bullet that will hold up well for deer and elk with out loosing accuracy. In the past I shot a .300 winchester and had trouble with the more accurate bullets exploding on impact.
0
-
racowboy1,
If you don't know the twist rate of a particular barrel or rifle you can use a cleaning rod to determine the rate of twist:
Twist rate is length down the barrel of a firearm that it takes for the rifling makes ONE complete turn.
To measure it, put a patch on a tight-fitting jag. Push the jag into the barrel until you feel it grab the rifling. Mark the top of the rod at the breach, and at the back of the rod. Push the rod until the mark on the back of the rod is facing up again. Mark the rod at the breach again. Measure the distance between the two 'foreward' marks - your twist rate will be 1:'your measurement' (e.g. 1:10" - 1 turn in 10 inches).
To save you a bit of trouble, I checked my factory twist rate chart and your rifle has a 1:10 twist. This will handle all bullet weights up to and including the 220 gr. Sierra Matchkings.
If you want to use the same bullet for both deer and elk, I would suggest the Nosler 200 gr. AccuBond. These have proven accurate in several calibers and rifles and will hold up to the velocity range of the 300 RUM. Other bullets that would be suitable are:
Swift A-Frame
Nosler Partition
Swift Scirocco
There are others of course but these are the ones that I've used or have seen used in the field.
Good powders for these bullets are:
Re-25 (favorite)
IMR-7828
H-1000
Ramshot Magnum
You should use a chronograph to work up your loads. The AccuBond will top out at about ~3000 FPS. in a 26" barrel. This is a MAXIMUM PRESSURE VELOCITY. But and it's a big BUT, be sure to work up slowly while watching for signs of pressure. If these signs appear before 3000 FPS., don't go any further, STOP. All rifles and barrels are different so use caution.
Best.
0
Please sign in to leave a comment.
Comments
1 comment