SmallCaliberCentral

I just got back from the range today, where I was Chronographing my loads. I shot 30 rds and this is what I came up with.


25.1 RL-10x
39 SBK
Rem 7 1/2
Hornady Case
Ogive: 1.860
COAL: 2.335

My average Velocity was 3931 FPS

That is 200 FPS more than the Sierra load manual states for this load. What Gives?

For what it's worth, my 32 V-max with 25.5 of RL-10x were going at 4124 FPS, that's about 200 FPS over the published data also

I'm shooting 24.8 gr. Of 10x with the 39 bk and getting 3850 fps out of a 28 inch encore barrel .

Not unusual.A few factors will change the FPS that much.Brass,capacity and neck tention.Chamber and barrel.Powdwe from different lots.

I've seen where;

- Sun light vs over cast;
- How high, low and centered the bullets fly over the sensors;
- Elevation;
- Environmental conditions;
- Distance from the muzzle to the chronograph;
- Any blast or other effects upon the chronograph.

There are probably others but these have skewed my numbers thru the years, not to mention the load itself.

barrel length and temp.

Let me guess. It's a Shooting Chrony.