I get some odd readings using coated bullets when shooting over an optical chronograph. Rifle is a 270 win with 22" barrel. Shooting a Nosler 140g AB that is coated with a black coating and red tip, from shooters pro shop. Using IMR4831 powder, Nosler data for this bullet weight shows a max of 53.5g @2910fps. Middle load is 51.5 @2790fps. I have an accurate load with 52g but velocity is only reading 2500-2550. I did not have a chrono when putting this load together. Is the chrono reading off because of the coated bullets? I do have some regular uncoated 140AB bullets so next step is loading a few with same load and chrono them.
Coated bullets and optical chronographs?
- Thread starter Philward
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I would think that those velocities are good. I have a 22" barreled Browning BBR 270 Win. With the 140 gr Sierra my load is 57 grs IMR 4831 and vel is 2822 ft/sec. 52g would be a very mild load in my rifle. JME
Just checked my notes and see where I used 52g of IMR4831 with a 150 gr Sierra, Velocity was 2577 ft/sec. Seems to match up somewhat with your load..
Just checked my notes and see where I used 52g of IMR4831 with a 150 gr Sierra, Velocity was 2577 ft/sec. Seems to match up somewhat with your load..
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