Dramatic drop in velocity with exact same components - strange! Ever seen this??

[big johnson]

Hey Bean you were a cute kid.

 

[Dr. Richard Gray]

Is it possible that you crimped one batch and not the other. This could have made a smaal difference but I wouldn't think it would be 200fps.

 

[Dr. Richard Gray]

86 gr load showed some minor ejector mark! Is it possible that you have damaged the gun?

 

[Chas1]

You can get scale calibration weights online from several sources. They can be used as a "sanity check" for the scale after calibration.

Exactly, every few rounds I'll throw calibrated weight on beam and digital scale just to be sure.

 

[ButterBean]

I"ve got an idea, Let's change everything the OP is doing at one time so when he goes back to the range and it shoots different he'll no idea what it was

 

[eric nelson]

Hot mag primers are (to me) very important in your case. Possibly try a different pack?

 

[ButterBean]

Is it possible that you crimped one batch and not the other. This could have made a smaal difference but I wouldn't think it would be 200fps.

86 gr load showed some minor ejector mark! Is it possible that you have damaged the gun?

Hot mag primers are (to me) very important in your case. Possibly try a different pack?

It was the Moon Phase, Just Sayin

 

[g0cherr]

I had this happen with a 300 WSM while trying to do range validation and nothing was making sense. Turned out I had my chrono a little too close and it was picking up unburnt powder. When I moved my chrono out a little further my velocity dropped 200 ft/sec and my range validation fell into line.

 

[Lymey]

I have a Browning X-Bolt in 28 Nosler I've been shooting for a couple of years with 143 gr Hammer Hunters. I recently got my hands on some ADG brass and N570 powder. I've been wanting to try some load workup with these new components. Went to the range a week ago to do pressure test and it went like this:

83 grains - 3465 fps with no pressures signs
84 grains - 3575 fps with no pressure signs
85 grains - 3600 fps with no pressure signs
86 grains - 3722 fps with slight ejector mark, no sticky bolt

Decided to focus around the 86 grain level (+/- .3 grains) to test accuracy.

Back at the range yesterday to try those loads and they shot .5 MOA BUT they all ran velocity around 3500 fps instead of around 3700.

I've been loading for 35 years and never seen anything like this. Components were exactly the same each time:

New ADG brass
N570 powder
CCI-250 primer
143 grain Hammer Hunter bullet

using Magnetospeed chrono

Anybody experienced anything like this?? It's driving me crazy trying to figure out why velocity would drop 200 fps with exact same components, seating depth, etc.

I haven't read of the possibility of pre-detonation.

 

[BigDon]

I haven't read of the possibility of pre-detonation.

Detonation is not a 200fps problem!

 

[Carlos88]

What a bunch of newbies.

It's the coreolis effect. Geez.

 

[ButterBean]

What a bunch of newbies.

It's the coreolis effect. Geez.

Right or left hand twist ?

 

[Carlos88]

Right or left hand twist ?

Left. It's always the left.

 

[ButterBean]

Left. It's always the left.