Berger Bullet Reloading Question

[the beast]

Currently, I am reloading a 6.5 x 55 Berger Bullet with a 140 grain VLD using IMR 4350. The book states that my load at 41.1 g should be 2675 fps but I am only getting an average of 2511 on 10 shots. It is an accurate load. It this acceptable?

Thanks,

 

[Korhil78]

How long is your barrel compared to the one that they did their fps test with?

 

[the beast]

I am using a 24 inch barrel like the one they are using

 

[BrentM]

I am not sure their data and ours is a logical match. Their barrel design, make, etc could be enough different combined with atmosphere to give significantly different results. For example I can not come anywhere close to using the amount of powder they do for max and my speeds are way higher, go figure.

 

[Korhil78]

This is what I got from the Hodgdon powder website with a 140 gr bullet and IMR 4350:

Min. powder charge 41.0 gr with velocity of 2486 fps

Max powder charge 45.0 gr with velocity of 2677 fps

So from the Hodgdon website, your velocity is pretty close to theirs for your powder charge of 41.5.

 

[Greyfox]

You might want to confirm that your chronograph readings are correct. Lighting conditions can produce false readings. Also, seating depth with Bergers can produce differing velocities depending in how deeply the bullet is seated. Are your bullets seated to the same depth as your reference load? If your bullet was seated at a different depth, you will get a different velocity, and will may use a different powder charge. These differences can be seen in some of the loads listed in the Berger Reloading Manual when I compare them to my loads using different seating depth. They explain this effect in their manual.

 

[BrentM]

You might want to confirm that your chronograph readings are correct. Lighting conditions can produce false readings. Also, seating depth with Bergers can produce differing velocities depending in how deeply the bullet is seated. Are your bullets seated to the same depth as your reference load? If your bullet was seated at a different depth, you will get a different velocity, and will may use a different powder charge. These differences can be seen in some of the loads listed in the Berger Reloading Manual when I compare them to my loads using different seating depth. They explain this effect in their manual.

Good point. I played with this last week on the chrono and noticed big swings from crushed into the lands to .100 out. In some cases almost 100 fps. Of course I was on the max side of things and getting pressure signs big time.