Range result differences when using different powder lots?

[VaniB]

Not engaged in shooting competition, I' don't normally need to buy more then 1 can of powder, because I usually do sight-in with a new rifle, make tight groups by the 3rd range visit, yawn, and then start my next rifle project.

My question is if I can expect to see a big difference in target groups between two different lots of H4350 that I bought 12 months apart. What a screw-up on my part.......as I have already gone through the first starting can of powder, but didn't get bored enough with this new 6.5 CM rifle to want to retire it yet! LOL I was getting some very tight clusters with the first can when I ran out of powder. Now I'm wondering if the 2nd can of powder I just opened will suddenly transform into mediocre groups where the shots won't even touch as they had been doing with the first can. A shift of the POI on paper will not bother me, as that can always be adjusted with some elevation/wind clicks. But, a loss of tight clusters would be my concern. Anybody care to venture and predict what I can expect?

 

[Immike]

I seriously doubt that you will see any difference. Don't plant your own seeds of doubt. I have been through dozens of lots without any problems. Maybe it was lucky or maybe I don't let it bother me.

Since you are not in competition it is not a matter of win or lose for you. Without detailed load development the small difference may be hard to see if it even exists. A competitor would know right away if they have a problem but most shooters wouldn't be able to tell. A elevation change at the longer distances would be a good indicator that you need to start over with load development. Other than that don't sweat it.

 

[VaniB]

I seriously doubt that you will see any difference. Don't plant your own seeds of doubt. I have been through dozens of lots without any problems. Maybe it was lucky or maybe I don't let it bother me.

I'm with you on that! Thanks.

I'm wanting to use the logic that when folks buy a box of 20 factory made cartridges at different dealers during the year, the components including the powder are going to be from different factory lots......yet the performace remains pretty good and much the same as what the shooter had previously experienced.

It's just that I had fired a preliminary test group with the new powder some weeks ago. The test group did not shoot anywhere as accurate as the old powder. But then again, maybe I was just having a bad day!! ...... LOL....... How many of us have fired identical loads from the same powder lot, using the same components and the same handloading teqniques to fire a sub 1/2" MOA group at 11:00 AM when we arrived, but then fired a final 1"MOA group at 1:00PM just before we left the range! I hate when that happens.;D

 

[Michael Courtney]

http://www.dtic.mil/dtic/tr/fulltext/u2/a572333.pdf

Our testing showed different lots of powder can give changes in muzzle velocity as large as 100 fps with H4831. Similar changes can probably also occur with H4350. Hodgdon recommends working up new loads with any change of components including different lots of their powder.

 

[watercam]

Seems like every lot of a familiar powder I try shows 30-40 fps more when compared to the end of the last lot I have shot. Beginning to believe that the older lot has lost a little oomph over time and the new lot re-energizes my loads with a breath of fresh air (or formaldehyde as the case were). In the end they all seem frightfully close to each other these days. One Palma Master opined that he just charges cases with X amount of Varget regardless of lot number and continues to shoot High Master scores day in and day out.

 

[VaniB]

http://www.dtic.mil/dtic/tr/fulltext/u2/a572333.pdf

Our testing showed different lots of powder can give changes in muzzle velocity as large as 100 fps with H4831. Similar changes can probably also occur with H4350. Hodgdon recommends working up new loads with any change of components including different lots of their powder.

Thank you for including that link, as I found it to be very interesting info. I will proceed with completing the 25 rounds of test loads I'm in the middle of hand loading with the new can of H4350 powder. (ie; 5 different test loads consisting of 5 cartridges each) Three of these test loads are already proven to be capable of 5/16" to 1/2" groups in my previous range visits with the first can of powder. In each of the groups, the shots had clustered. If I cannot get this same kind of accuracy again with the new powder, then I'll know that the powder almost certainly has to be the culprit.

 

[Mega]

Thales (ADI) Australia go through a lot of testing to ensure changes in Batch Lot's do not vary any noticeable amount but Batch Lot's many years apart may have some differences, I would not imagine very much. I have an older 4kg bottle of AR2208 (Hodgdon Varget for you guys) which is coming to an end and a new Batch some 2 years difference, in a 6.5x47 Lapua my point of impact nor velocity changed between the two so I have not changed anything for my new batch loads.

I talk with my friend that actually does the testing for Thales of powder batching lots and it's quite mind blowing how much is involved. Pity is that he can't get supplies of powder direct and even here in Oz some powders are really hard to source in quantity.

Maybe any difference is in how the powder has been stored over a period of time and may be different to a fresh bottle in that respect.

I use AR2207 (Hodgdon H4198) in my 30BR but I can't get a 4kg Bottle so I buy 8-12 500gr Bottles all the same batch. I believe in the smaller bottles it keeps better as they are not opened until ready to use so less likely any affects from being opened. Usually can get a price close to that of a larger bulk container.

 

[Michael Courtney]

The biggest storage issue is humidity. A new unopened powder has a low moisture content. In Hodgdon's testing they leave the powder canister open for a day or two to acclimate to the reloading environment. If the humidity in the reloading area is consistent and the powder is acclimated before loading and during storage, then the biggest storage issue will be minimized.

Don Miller wrote a great article on this in Varmint Hunter Magazine some time ago. Powder that has absorbed moisture has two main effects: 1) The same mass of powder actually has less fuel, because it has absorbed some water. 2) When the powder burns, some of the energy is absorbed evaporating the water so it is unavailable to push the bullet from the barrel.

I suspect the loss of 40 fps or so as a canister or powder is worked through can be eliminated by acclimating the powder to the reloading area and maintaining a relatively consistent humidity in the reloading area. This is our laboratory procedure, and it works well. However, it does not eliminate lot to lot variations in powder performance, as these are due to inherent variations in the powder which Hodgdon is apparently unable to control.

 

[louielouie]

...
I suspect the loss of 40 fps or so as a canister or powder is worked through can be eliminated by acclimating the powder to the reloading area and maintaining a relatively consistent humidity in the reloading area. This is our laboratory procedure, and it works well.
...

I was thinking that small desiccant packs could be useful at removing the accumulated moisture once the canister has been opened and perhaps retard deterioration. I try to reduce exposure in my electronic powder thrower and return it to the canister ASAP but I'm sure the effect is cumulative until it reaches ambient humidity.

BTW, thank you for the article - some of the supplied links were most informative, too.

 

[artbosco]

A different lot of the same powder is essentially a different powder. Work up a new load. There's no way around it.

 

[savagedasher]

A different lot of the same powder is essentially a different powder. Work up a new load. There's no way around it.

You also can do what I have done. I have 4- 8# jugs of varget I put them in a clean 5 gal bucket with a lid and shook them together and now I have 32# of the same powder. Same with my H 4350. I still have 50# of IMR 4831 un open that I gave $31.50 for 50#.
Larry

 

[VaniB]

A different lot of the same powder is essentially a different powder. Work up a new load. There's no way around it.

As mentioned in my 3rd post, the first 4 sentences; if what you say were true, then for example, nobody could buy a box of Hornady 6.5 Creedmoor cartridges off of the shelf from another store and expect the same fine accuracy they had gotten the last time they were at the range. Guys are reporting Savage LRP rifles shooting 1/2" MOA with factory cartridges.

For, that matter, then any box of factory cartridges in any caliber would not be capable of maintaining the same kind of fine accuracy due to changes in powder lots. Dunno.....maybe you're right. (??) Maybe guys are lucky to get repeatable accuracy with the next box of factory ammo they buy. (?)

 

[VaniB]

A different lot of the same powder is essentially a different powder. Work up a new load. There's no way around it.

You also can do what I have done. I have 4- 8# jugs of varget I put them in a clean 5 gal bucket with a lid and shook them together and now I have 32# of the same powder. Same with my H 4350. I still have 50# of IMR 4831 un open that I gave $31.50 for 50#.
Larry

Larry,
That makes logical sense in my mind too......that if you mix it all together, you now get one uniform lot that should provide the same performance. But I have been told by others never to do that.

 

[mikecr]

Your notion that various lots of powder and off the shelf ammo are the same fails tests. They are often not the same.
Hell, factory ammo even of the same lot# exhibits shifts. And it's difficult for me to imagine experienced reloaders that haven't noticed changes in powders on replacement.
I've run into this with varget and IMR4350, and I ran into it with Winchester factory in 223.

What I do(this is just me) is I make sure a source of powder has enough of a given lot for the life of my barrel -before I buy any of it to develop with. This way, when I'm happy with my load I can buy enough of the same powder to sustain it. Otherwise and with my luck, I'll likely waste some efforts and barrel life.

On powder mixing;
It's really important to know your ammo is right so that you can manage & troubleshoot result issues.
Unless verified that components of a powder mix truly match, you'll just never be able to rule it out of cause.
Same with mixing brass, or bullets. You don't want to add any abstracts to your processes.

 

[artbosco]

A different lot of the same powder is essentially a different powder. Work up a new load. There's no way around it.

You also can do what I have done. I have 4- 8# jugs of varget I put them in a clean 5 gal bucket with a lid and shook them together and now I have 32# of the same powder. Same with my H 4350. I still have 50# of IMR 4831 un open that I gave $31.50 for 50#.
Larry

Or, better yet, what I have done. Bought multiple 8-lb jugs of the same lot.

 

[Judd]

A different lot of the same powder is essentially a different powder. Work up a new load. There's no way around it.

As mentioned in my 3rd post, the first 4 sentences; if what you say were true, then for example, nobody could buy a box of Hornady 6.5 Creedmoor cartridges off of the shelf from another store and expect the same fine accuracy they had gotten the last time they were at the range. Guys are reporting Savage LRP rifles shooting 1/2" MOA with factory cartridges.

For, that matter, then any box of factory cartridges in any caliber would not be capable of maintaining the same kind of fine accuracy due to changes in powder lots. Dunno.....maybe you're right. (??) Maybe guys are lucky to get repeatable accuracy with the next box of factory ammo they buy. (?)

Ammo makers are testing those different lots of powders to make sure they are consistent across different boxes of factory ammo. Essentially, they are matching load results and not loading the same recipe every time.

I had an 8lb'er of Varget and was getting kinda low so picked up another. It's weird I know but I cannot for the life of me figure out a load the dasher will shoot with this load of powder. Fortunately, it appears my brx will shoot it but there is differences in lots...believe it or not but I do.

 

[mikecr]

Ammo makers are testing those different lots of powders to make sure they are consistent across different boxes of factory ammo. Essentially, they are matching load results and not loading the same recipe every time.

Factory standards are nowhere near reloading standards. 'Matching load results' on their part means still safe and close enough to the velocities on the box that -they don't have to reprint their boxes..
Some of it shoots the same, some of it don't.

 

[Joe Salt]

Thats a Rookie mistake changing lot numbers and expecting the same results, If you chronographed your load, do it again with the new lot to be sure! Don't guess.

Joe Salt

 

[savagedasher]

Back 55 years when I first started reloading. I would buy a pound can when ever I could afford it.
I could only get 70 round out a pound. I found one pound shot different then the other. So I had 65 rounds that shot good and 35 that didn't. My uncle who taught me to reload told me to mix the two pounds together. I never had a problem after that. I don't even know if the cans had lot numbers back then. I never had problem mixing the same brand and number together. I have 4 8# containers of Varget I mixed together. Now I have 32# of my lot. At 75 that will last me a life time shooting a dasher. Larry

 

[VaniB]

It's not that I haven't spent a lifetime handloading accurate loads for my guns, as much as I normally never fire a bolt action rifle beyond 1 can of powder before I'm satisfied enough with it to get bored and then buy another rifle. I don't hunt, and I don't shoot competitively, so 1 can of powder has usually been sufficient for that to happen. This 6.5 Creedmoor has been requiring more tests then my previous bolt actions, and surprise, surprise......I burned through my fist 1lb can of powder trying to shrink 1/2" groups down to consistant 1/4" - 3/8" groups. In the last few years, I've been shooting AR rifles in 223 and 308, and I've burned through many more handloads using different powders. But the 3/4" -1" groups I shoot with my AR gassers aren't as demanding as the 1/4" or 3/8" groups I seek with this 6.5CM bolt action. The changes from powder lot to lot with the gassers haven't been as critical or noticeable in accomplishing those kinds of larger groups. The revolver and pistool shooting I've done in years past are also much less demanding on accuracy so that the results of different powder lots aren't so critical.

Thanks for the input gents. I guess I'm fixing to find out in another week or so when I return to the range, just how that 2nd lot of H4350 powder is going to act!