Why do I need so much powder?

[Huntnful]

I've been reloading for my 28 nosler for a little under a year now. But loaded about 300 rounds, doing various load development for several bullets with great results. I've strictly used N570 with ADG and Peterson brass and 215M's. All of my loads now are consistently taking more than average amounts of powder to reach previous pressures and standard velocities. But it didn't initially need that much powder from my early data. Who's got ideas? Also, loads that I loaded up way in the beginning and verified velocity, now shoot at a considerably lower velocity. Like 100 FPS slower. FYI gun is custom built and throated for 195's to seat with the boat tail at the edge of the case neck.

Examples.

OLD LOADS
195 Berger. 81.5 gr. N570 3030 FPS
169 Hammer Hunter 84 gr. N570 3300 FPS

NEW LOADS
195 Berger 84gr. N570 3030 FPS
169 Hammer Hunter 88gr. N570 3300 FPS
180 Berger Hybrid 87.5 gr. N570 3185 FPS

Pressure signs are velocities are the equivalent as prior, just takes way more powder. I do everything safely and work my loads up slowly, but I'm genuinely curious on what gives? Thank you for your input and advice.

 

[Andrew Massi]

Best wild guess- Throat erosion
The 28 nolser has pretty wicked throat erosion especially with n570.
Has your cbt lands measurement changed?

 

[Jud96]

Couple things. Did you test the loads with once fired brass before it took more powder to reach the desired speed? Once fired brass will deliver different velocity than virgin brass. Also, is the powder all the same lot? Have you adjusted seating depth at all? Were you close to or in the lands in your previous testing before it sped up?

 

[Orange Dust]

Best wild guess- Throat erosion
The 28 nolser has pretty wicked throat erosion especially with n570.
Has your cbt lands measurement changed?

This...

 

[Huntnful]

Best wild guess- Throat erosion
The 28 nolser has pretty wicked throat erosion especially with n570.
Has your cbt lands measurement changed?

I've had about .01 throat erosion. Not crazy bad.

Couple things. Did you test the loads with once fired brass before it took more powder to reach the desired speed? Once fired brass will deliver different velocity than virgin brass. Also, is the powder all the same lot? Have you adjusted seating depth at all? Were you close to or in the lands in your previous testing before it sped up?

I've tested both virgin and once fired brass and get VERY similar velocities. Within 10 FPS. My fired brass is only .002 larger than virgin brass and I basically FL size it back to virgin measurements.

So with the powder. I had an original 8lb keg. I got down to about 4lbs and bought four 1lbers from a buddy. I poured all 8lbs into a big tuperware and mixed it all thoroughly. Then put the "new lot" back into the 8lb jug. This would lead me to believe this is 100% the culprit BUT my old loads that I loaded with the very original 8lb now shoot considerably slower. Could the powder be settling in the case over time and just not taking up as much volume? Also, I stay out of the lands.

 

[Andrew Massi]

Doubt it's your new combo powder lot. I have Zero experience with N570 but I've mixed other super slow powders and hybrid lots of slow burning powders seem to be the least sensitive to mixing.

 

[Huntnful]

Best wild guess- Throat erosion
The 28 nolser has pretty wicked throat erosion especially with n570.
Has your cbt lands measurement changed?

I understand that it's a hot round and erodes the throat, which from what I knew just effected the accuracy. Could you enlighten me on how it could effect the velocity by 100-200 FPS (in some cases) considering that I will keep the bullet right near the lands? Case capacity changing? Or is it actually how the bullet interacts with eroded lands compared to pristine lands?

 

[Huntnful]

I should also clarify, this gun is still a tack driver haha. Just curious on the higher than average powder charges. I'm also not super deterred by the added cases fill. I get legit ES & SD's with having the cases filled up near the shoulder haha.

 

[308win]

I've been wanting to start a thread and ask the same question....here's what I'm running into.

My reloading room is separate from my shooting range. I can shoot out the backdoor of the reloading room and do testing powder charges. I will put a charge together and step out the door and fire over a Labradar to verify velocity and immediately go put the information into quickload and adjust as necessary. Next I put 3 rounds together and again verify with the Labradar. When I get to the desired results I immediately load up another 3 shot string to verify at the range. This is where it gets interesting.....I'm usually able to go out and shoot the next day but sometimes it's a week or more? Regardless, my velocities decrease on average by 100fps from loading room to range. I have 2 different theories, either the Labradar is subject to differences in temperature (going from a 72° a/c room to 90°+ Texas heat within minutes) or there is some kind of brass relaxing going on and giving me less neck tension? I don't know enough about the subject to say either way, just my observations. Interested to see what kind of Chronograph you are using and at what temperature? The Labradar is a doppler device and I wouldn't think it would be effected by temperature, but then again.....electronics???

 

[Calvin45]

I've been reloading for my 28 nosler for a little under a year now. But loaded about 300 rounds, doing various load development for several bullets with great results. I've strictly used N570 with ADG and Peterson brass and 215M's. All of my loads now are consistently taking more than average amounts of powder to reach previous pressures and standard velocities. But it didn't initially need that much powder from my early data. Who's got ideas? Also, loads that I loaded up way in the beginning and verified velocity, now shoot at a considerably lower velocity. Like 100 FPS slower. FYI gun is custom built and throated for 195's to seat with the boat tail at the edge of the case neck.

Examples.

OLD LOADS
195 Berger. 81.5 gr. N570 3030 FPS
169 Hammer Hunter 84 gr. N570 3300 FPS

NEW LOADS
195 Berger 84gr. N570 3030 FPS
169 Hammer Hunter 88gr. N570 3300 FPS
180 Berger Hybrid 87.5 gr. N570 3185 FPS

Pressure signs are velocities are the equivalent as prior, just takes way more powder. I do everything safely and work my loads up slowly, but I'm genuinely curious on what gives? Thank you for your input and advice.

It's a conspiracy!!!! All burn rates are slowing down compared to old powders (as opposed to older lots having deteriorated and increasing in burn rate) so us dummies will have to buy more powder. Or they're watering the stuff down with graphite coated sawdust.

 

[Orange Dust]

Guess??? Temp difference, and, does anyone know if Labrador is affected by air density? Only way to be sure is drop tests. 100fps should show up

 

[Huntnful]

I've been wanting to start a thread and ask the same question....here's what I'm running into.

My reloading room is separate from my shooting range. I can shoot out the backdoor of the reloading room and do testing powder charges. I will put a charge together and step out the door and fire over a Labradar to verify velocity and immediately go put the information into quickload and adjust as necessary. Next I put 3 rounds together and again verify with the Labradar. When I get to the desired results I immediately load up another 3 shot string to verify at the range. This is where it gets interesting.....I'm usually able to go out and shoot the next day but sometimes it's a week or more? Regardless, my velocities decrease on average by 100fps from loading room to range. I have 2 different theories, either the Labradar is subject to differences in temperature (going from a 72° a/c room to 90°+ Texas heat within minutes) or there is some kind of brass relaxing going on and giving me less neck tension? I don't know enough about the subject to say either way, just my observations. Interested to see what kind of Chronograph you are using and at what temperature? The Labradar is a doppler device and I wouldn't think it would be effected by temperature, but then again.....electronics???

I mean, I have gotten all my previous velocities from a magneeto speed and buddies lab radar. Now I have my own lab radar and I consistently need more powder to reach velocities BUT my velocities still coincide when we use my buddies lab radar sometimes when we shoot. But the electronics could play a small role. Irregardless, my pressure signs match up with my velocities and all previous data and also most data people have gathered with their pressure signs and velocities.... I just need more powder to get there.

 

[Orange Dust]

I mean, I have gotten all my previous velocities from a magneeto speed and buddies lab radar. Now I have my own lab radar and I consistently need more powder to reach velocities BUT my velocities still coincide when we use my buddies lab radar sometimes when we shoot. But the electronics could play a small role. Irregardless, my pressure signs match up with my velocities and all previous data and also most data people have gathered with their pressure signs and velocities.... I just need more powder to get there.

Something is different. Best guess is barrel wear.

 

[Huntnful]

Something is different. Best guess is barrel wear.

It could be man. As long as I can keep a good group with good velocities i'll just keep feeding her powder haha. I was just curious.