new lot of powder average 37 FPS slower

[wsftr]

Hi,
I have a new lot of ADI 2208 powder that is averaging 37ps slower than the previous lot.
Groups have opened up close to double. nothing else is changed just the powder lot.
ES/SD on the new lot are ok.
How have you brought the load back into tune - just increased powder to get FPS back or left charge the same and adjusted the tuner/ seating depth? I would need to add in approx 6/10ths more powder.
This is Lapua cases ADI 2208 and Berger 185s.

TIA

[Rogue22]

This seems to be the norm of late, I’ve typically only had to add 0.2gr to get back into tune, group and SD wise. Still running them slower than previous batches though. I’d do another powder charge test to see where it likes to shoot.

[PeteFox]

I have had this happen.
This may not be true for your powder lot but this is how I fixed it with 2209.

In my case I traced it back to the powder having an elevated moisture level . Changing the load will increase the average velocity, but I found that it did nothing to improve group size.
You will need a Kestrel Drop or similar to check this. You will find these available cheaper on Amazon or EBay
What I have found is this:
- 2209 powder from the factory has an moisture level of around 51-52% when measured using this method .
- the lid is not always tight from the factory and depending on the storage, over time it may absorb moisture.
- I suspend a Kestrel in a tightly sealed jug for 24 hrs to get a stable moisture reading. The Kestrel has a bluetooth connection and can be read without disturbing it. Temperature variations will change the reading because you are reading relative humidity not absolute humidity.
- 2209 powder with an elevated moisture content of of 57% didn't group and was around 30 fps slower
- I fixed this by placing the powder in an open tray in a controlled humidity room (45%) for 24 hrs. I then put it back into the jug with a Kestrel, left it for 24 hrs and retested. You may have to do this a number of times as releasing the moisture is a slow process.

Moisture in powder has these effects:
1. if you are dispensing powder by weight, you are weighing some extra moisture which means that you are putting less powder in each charge
2. the moisture is boiled off during combustion , which takes energy that is not going into propelling your projectile -

I suspect, but cannot prove that the moisture is not evenly distributed throughout the powder, and that moisure is in higher concentrations near the top of the jug. when poured into the thrower hopper there are patches of high and low moisture content which accounts for the variable velocity/group size.

This is just what I have found, and may not be true for your situation as there are many factors in play.
Don't take my word for it, do your own research. There is a good article here for H4350 which is 2209 >> https://chronoplotter.com/2021/08/19/ho ... ct-powder/
It takes a while to digest, but it is worth the read.
Pete

[Malcolm Hill]

Hi TIA. I started on a new batch of 2208 (MEM7503) a few months ago and was over 100fps slower than all previous batches. Running Lapua brass, cci200, Berger 155.5 fullbore normal velocity of 3000fps used 46.0/46.1gn of 2208 with most previous batches. Lot no 7503 running 46.0 gave 2885fps, I thought the first reading on the lab was a mistake. No it wasn't that was the velocity. I always test new powder batches shot for shot with the previous batch with everything the same other than the powder. I contacted ADI regarding the issue and they were extremely helpful. They went to the trouble of obtaining some 155gn projectiles (they normally do all their pressure testing with168gn) and retested lot no MEM7503 of 2208 and confirmed my results of it being on the very slow side of their specifications. Pressure wise I was told it was quite safe at 48gns (they tested it up to 49gns before pressure was above limits). I am now loading at 47.4/47.5gn to achieve 3000/3010fps whereas any previous batch in the last 15 years (and I have used a bloody heap of it) was usually around 46.0gn for the same speed. This batch of 2208 in particular is right off the pace and needs considerably more charge rate than all previous lots. Don't however just throw in a heap more powder without doing your normal pressure checks but don't be surprised if you end up using more than you would expect to achieve your previous results. I would be interested to know the lot no. of your powder. Regards Malcolm.

[willow]

I have had this happen.
This may not be true for your powder lot but this is how I fixed it with 2209.

In my case I traced it back to the powder having an elevated moisture level . Changing the load will increase the average velocity, but I found that it did nothing to improve group size.
You will need a Kestrel Drop or similar to check this. You will find these available cheaper on Amazon or EBay
What I have found is this:
- 2209 powder from the factory has an moisture level of around 51-52% when measured using this method .
- the lid is not always tight from the factory and depending on the storage, over time it may absorb moisture.
- I suspend a Kestrel in a tightly sealed jug for 24 hrs to get a stable moisture reading. The Kestrel has a bluetooth connection and can be read without disturbing it. Temperature variations will change the reading because you are reading relative humidity not absolute humidity.
- 2209 powder with an elevated moisture content of of 57% didn't group and was around 30 fps slower
- I fixed this by placing the powder in an open tray in a controlled humidity room (45%) for 24 hrs. I then put it back into the jug with a Kestrel, left it for 24 hrs and retested. You may have to do this a number of times as releasing the moisture is a slow process.

Moisture in powder has these effects:
1. if you are dispensing powder by weight, you are weighing some extra moisture which means that you are putting less powder in each charge
2. the moisture is boiled off during combustion , which takes energy that is not going into propelling your projectile -

I suspect, but cannot prove that the moisture is not evenly distributed throughout the powder, and that moisure is in higher concentrations near the top of the jug. when poured into the thrower hopper there are patches of high and low moisture content which accounts for the variable velocity/group size.

This is just what I have found, and may not be true for your situation as there are many factors in play.
Don't take my word for it, do your own research. There is a good article here for H4350 which is 2209 >> https://chronoplotter.com/2021/08/19/ho ... ct-powder/
It takes a while to digest, but it is worth the read.
Pete

I experienced this recently with 2209 also, with humidity levels in Sydney being quite horrendous this summer, I had one jug go south on me, dropping my velocity by a similar margin and taking me right out of the accuracy node with my 7-6.5 PRC. I managed to dry the powder out but took too much moisture, resulting in velocity jumping about 20fps above what it needed to be. Fun and games...

[wsftr]

Hi TIA. I started on a new batch of 2208 (MEM7503) a few months ago and was over 100fps slower than all previous batches. Running Lapua brass, cci200, Berger 155.5 fullbore normal velocity of 3000fps used 46.0/46.1gn of 2208 with most previous batches. Lot no 7503 running 46.0 gave 2885fps, I thought the first reading on the lab was a mistake. No it wasn't that was the velocity. I always test new powder batches shot for shot with the previous batch with everything the same other than the powder. I contacted ADI regarding the issue and they were extremely helpful. They went to the trouble of obtaining some 155gn projectiles (they normally do all their pressure testing with168gn) and retested lot no MEM7503 of 2208 and confirmed my results of it being on the very slow side of their specifications. Pressure wise I was told it was quite safe at 48gns (they tested it up to 49gns before pressure was above limits). I am now loading at 47.4/47.5gn to achieve 3000/3010fps whereas any previous batch in the last 15 years (and I have used a bloody heap of it) was usually around 46.0gn for the same speed. This batch of 2208 in particular is right off the pace and needs considerably more charge rate than all previous lots. Don't however just throw in a heap more powder without doing your normal pressure checks but don't be surprised if you end up using more than you would expect to achieve your previous results. I would be interested to know the lot no. of your powder. Regards Malcolm.

this bottle is MEM7494.
I wont go down the drying route for 40 fps. Until the shortages I have always had a barrels worth of components, powder etc.
Based on the chrony averages I need about 6/1oths more so I'll see how that goes.
mostly I am curious if people do a complete ladder with the new lots of powder or if you add in powder until fps is back and then adjust seating depth/tuner to tweak if needed.
if components weren't short I would just start over but I'm hoping I don't have to depending on others experience.