Not long range, but

[AKBman]

I have a question. I am loading for the 375 Ruger, and I am getting excellent accuracy with the Hornady 300gr RN bullets. However, I have found that my velocities aren't what I was expecting. Being between chronos, I am using a ballistics calculator to figure out my velocity. I am using a load shot in the same barrel length and action, but instead of the 2600FPS published in Handloader, my ballistics calculator shows the velocity to be closer to 2300FPS. I shot a group at 100 yards, and then I shot a group at 200 yards, I took the measurement between the groups and started playing with the input velocity until the calculated 100 and 200 yard measurements matched. I am not using the exact components, they used CCI primers, I am using Federal, I also am not seating the bullets as deep. Would this be enough to cost me 250+ FPS? I am planing o using this rifle on an upcoming cow elk hunt, and I am not likely to change the load between now and then, but until I get another chrony, are the ballistic calculator's numbers to be trusted?

 

[varmintH8R]

My 2C is that you would have to go out quite a bit farther than 200yds to use drops to verify velocity. Too much margin for error and other factors that can give you false feedback.

 

[AKBman]

Thank you sir, I will try taking it out to 300 yards.

 

[WildRose]

To your question, seating depth can have a big effect on chamber pressure and velocity.

I agree though you need to move out considerably further with your drops to get good confirmatory data. I'd suggest 400yds if you have a place you can shoot that far. Around Alamogordo that shouldn't be too hard to find though LOL.

 

[AKBman]

Once you get away from the scrub brush, 400 is easy, a target big enough to contain the drop is another story. The local range is setup for out to 300.