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

Chas1

Well-Known Member
Joined
Feb 15, 2009
Messages
3,937
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

Well-Known Member
LRH Team Member
Joined
Feb 5, 2012
Messages
5,508
Location
West Terre Haute Indiana
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
train-crash.gif
 

ButterBean

Well-Known Member
LRH Team Member
Joined
Feb 5, 2012
Messages
5,508
Location
West Terre Haute Indiana

g0cherr

Well-Known Member
Joined
Dec 21, 2009
Messages
61
Location
Pilot Rock, Oregon
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

Well-Known Member
LRH Team Member
Joined
Sep 15, 2020
Messages
110
Location
Montana
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.
 

Recent Posts

Top