Different powder lots

[Megalodon]

So I know there can be variation, and loads may need tweaking, but holy crap, it’s frustrating what I’m seeing with my Creedmoor load.

Trying to figure out if this is really normal or what, and if there’s anything I can do in short notice.
Load is 41.6 gn H4350. Exact same brass, projectile, same environmentals. Average velocities are about 10 fps apart, new lot being lower.

Did OCW which I posted here, with almost every charge weight sub moa. Decided on 41.6. Did a seating depth test with sizes all between .85 and .40 moa. Decided on just under mag length.

Seating depth test was yesterday. Loaded 20 to get velo data and shoot 4x5 groups. And like a dumbass realized I need to switch to a new 8lber.

Sizes now are: 1.3, 0.92, 0.73, 1.00


I would work it back up I guess, but here’s were I’m even more of a dumbass. I’ve got a 3 day shooting school I’m leaving for Tuesday at noon that I need 300 rounds for. Never would’ve guessed there would be this much deviation. Is there anything “quick fix” I could do??? With the OCW all pretty accurate I don’t know that upping powder to match velocity would help?



Am I over thinking it? Factory Hornady stuff shoots good, but I really don’t want to pay as much as I did for the class in just ammo. But also don’t want to waste the class or the other peoples time.

 

[35WhelenAI]

Yes, different lots of powders can vary. Manufacturers want to keep a certain tolerance, but I've seen it happen with ball powders and extruded powders. Sometimes it's more, sometimes it's less. But it sure can be frustrating.

You talk about two lots of powder being 10 fps apart. Then needing to open an 8 lb'er. It sounds like you are saying between the first two lots you used there was 10 fps and the new eight pounder is where the big discrepancy occurs.

In a nutshell, I would give it a chance to tighten back up by bringing the velocity back to where it was. You'll have to do a bit of loading to work up but you should have a pretty good idea of how to get there from working with this cartridge so much.

If it helps, you're in business. If it doesn't, then you're right where you are now, debating to take what you can load yourself or buying Hornady ammo. Always worth a shot I think.

 

[Lawnboi]

Environment can cause a shift like that as well. Honestly 10fps isn’t squat.
Humidity the powder is at, lot, scale condition when it was loaded, can all have an effect.

As for the group sizes I don’t pay much attention to a few rounds when pressure testing, looking at what the barrel does as it breaks in means more, the bigger your sample size gets for a particular load, the more you can spot a difference. This usually isn’t accomplished in the first 20 or 30 rounds. If your barrel is new that may also be a reason for the speed increase.

If you want to test load down a tenth or two and shoot two ten rounds groups next to each other, see if that 10fps makes a difference. If you’re load is that finicky I’d probably abandon the bullet and try something different, after playing a bit with seating depth.

Also fwiw, if your 6.5 cm dosnt shoot a 140 decent over ~41.5grains of h4350, something else may be the culprit.

 

[Megalodon]

Sorry. Was frustrated and not completely clear.

Rifle has probably 300 rounds on it. 150 in its current configuration (factory before started loading). Picture below was my OCW test in order of charge weight. 41.6 was in the middle of the two middle groups. With the 41.6 load I had a 10 shot 0.8 moa group, then 10x3 groups for the seating depth test all between 0.8 and 0.4 moa. All of these shots were from a single 1 lber. It was getting low so before I was gonna sit down and load up 300+ I took 20 rounds with the new lot to just make sure. That’s when it seems like the groups opened up. Difference was 13 fps average between the two lots, but in the original OCW 41.4-41.8 had the exact same poi.

The seating depth rounds and the 20 with new jug were loaded 24 hrs apart, nothing really new with weather or anything.

Maybe it was just a bad day shooting, but I’m really second guessing it now with the class Wednesday. Don’t have any range time left either. Indoor range in closed mondays and it just dumped 5” of snow. Shoulda thought this through better.

I’ll probably do both, buy Hornady and load 300 up .2 gn and just see how it goes.

 

[BRTreedogs]

Do you still have ammo from the old lot to verify the rifle will still group?

 

[35WhelenAI]

Do you still have ammo from the old lot to verify the rifle will still group?

Good thought, if you have some and are able to use those to verify when you get where you are going.

Sorry. Was frustrated and not completely clear.

Rifle has probably 300 rounds on it. 150 in its current configuration (factory before started loading). Picture below was my OCW test in order of charge weight. 41.6 was in the middle of the two middle groups. With the 41.6 load I had a 10 shot 0.8 moa group, then 10x3 groups for the seating depth test all between 0.8 and 0.4 moa. All of these shots were from a single 1 lber. It was getting low so before I was gonna sit down and load up 300+ I took 20 rounds with the new lot to just make sure. That’s when it seems like the groups opened up. Difference was 13 fps average between the two lots, but in the original OCW 41.4-41.8 had the exact same poi.

The seating depth rounds and the 20 with new jug were loaded 24 hrs apart, nothing really new with weather or anything.

Maybe it was just a bad day shooting, but I’m really second guessing it now with the class Wednesday. Don’t have any range time left either. Indoor range in closed mondays and it just dumped 5” of snow. Shoulda thought this through better.

I’ll probably do both, buy Hornady and load 300 up .2 gn and just see how it goes.

Ok, thanks for the clarification! The velocity difference is a moot point, I can sure understand where you are coming from, no fun to have groups open up. With that said, I don't see those groups are that terrible. Sure one of them is a good bit larger but the other three are 1" or under. What distance will you be shooting? Quite honestly if it was me I would load up the three hundred rounds and have at it. If you're in the position to buy the Hornady rounds, have those as a back up and you can always switch.

 

[id_jon]

Sorry. Was frustrated and not completely clear.

Rifle has probably 300 rounds on it. 150 in its current configuration (factory before started loading). Picture below was my OCW test in order of charge weight. 41.6 was in the middle of the two middle groups. With the 41.6 load I had a 10 shot 0.8 moa group, then 10x3 groups for the seating depth test all between 0.8 and 0.4 moa. All of these shots were from a single 1 lber. It was getting low so before I was gonna sit down and load up 300+ I took 20 rounds with the new lot to just make sure. That’s when it seems like the groups opened up. Difference was 13 fps average between the two lots, but in the original OCW 41.4-41.8 had the exact same poi.

The seating depth rounds and the 20 with new jug were loaded 24 hrs apart, nothing really new with weather or anything.

Maybe it was just a bad day shooting, but I’m really second guessing it now with the class Wednesday. Don’t have any range time left either. Indoor range in closed mondays and it just dumped 5” of snow. Shoulda thought this through better.

I’ll probably do both, buy Hornady and load 300 up .2 gn and just see how it goes.

Overlaying all those groups together looks like a perfectly acceptable 30 round group to me.

 

[Couescrazy33]

Ya, I dont see any issues at all.

 

[EdP]

If I have followed this correctly you are comparing the size of 3 shot groups (photo) from one powder batch to 5 shot groups from another powder batch. You have got to expect 5 shot groups to be a bit bigger than 3 shot groups. I'd say load em up and go to school.

 

[Lawnboi]

I’d also load and go to school.