When changing powder lots....

[The Oregonian]

I recently (2 weeks ago) got my first custom and had a load work up done at the same time. That was with his lot of powder and I need to move to my lot.

I have done 1.5 load developments so far...it seemed to take a lot of work, meaning shooting time. I checked in .5 gr increments with 5 shot groups, then went to .2 gr for fine tuning. I would like to avoid that long process. For this.

Should I look for same muzzle velocity as previous lot and then confirm that powder charge with group size? Seems like the same brand of powder with similar muzzle velocity would have the same chamber pressure and barrel harmonics and this method would seem logical to me.

It is a 30-06 with 24" barrel and 2790 velocity with 180gr Nosler BT using 57 gr of H4350 if that helps.

Thx

Tom

 

[Greyfox]

When I have changed powder lots I will check the new powder for accuracy, velocity, and ES. It's been a crap shoot. I have seen identical results with different lots, but on occasion I have seen differences in the velocity. If this is the case, I will adjust the charge to match my original velocity then recheck accuracy and ES. A couple of years ago with my 6.5x284 a new lot of Retumbo required a 2 gr reduction to match the ballistics of my originsl load. It wasn't too much of a fuss, and my results with the new lot were identical once done. I recently acquired another case of Retumbo(new lot) for my 300WM. Out of curiosity I tested it in my 6.5x284 and results were identical to my last lot. It's more difficult these days, but it pays to buy a sufficient supply of the same lot of components when developing a long range load, particularly powder and bullets.

 

[safarihunter]

Every now and again you get lucky and nothing changes.

I'm with Greyfox, stock up on the same lots of components and you will only have to worry about that every few years.

More fun shooting and less time reworking your loads.

 

[The Oregonian]

I have a new 8lb jug and a few one pounders left, so I may just mix them all together and have 11 lbs or so. Should last about 1300 rounds, and I have plenty of primers as well.

I will plan to reach the same velocity and then validate groups to see if similar grouping is there.

 

[barefooter56]

I recently (2 weeks ago) got my first custom and had a load work up done at the same time. That was with his lot of powder and I need to move to my lot.

I have done 1.5 load developments so far...it seemed to take a lot of work, meaning shooting time. I checked in .5 gr increments with 5 shot groups, then went to .2 gr for fine tuning. I would like to avoid that long process. For this.

Should I look for same muzzle velocity as previous lot and then confirm that powder charge with group size? Seems like the same brand of powder with similar muzzle velocity would have the same chamber pressure and barrel harmonics and this method would seem logical to me.

It is a 30-06 with 24" barrel and 2790 velocity with 180gr Nosler BT using 57 gr of H4350 if that helps.

Thx

Tom

The Oregonian,
I back off about 2 grains and then work back up (or down depending on if the new lot is a lot hotter than the last) with the same bullet seating depth that worked before until I find my velocity accuracy node again. Never tried the mixing powder thing. You may want to contact the manufacturer to see what they say about that.