Home Forums Reloading Big Game Rifles Different Lot's Of The Same Powder Can Vary

There can be as much as a 10% variance in different lots of the same powder. My friends and I have loaded many rounds for different cartridges over the years and found there is a difference in powder by as much as 10%. For example: In my Mark V 300WBY, I load a 180gr TSX in front of 84.5grs of RL-22. Now before anybody panics please read the rest before responding. Yes, this load is 4.5grs over book. Now I just did not jump up and say ok I will load 4.5grs over book and put my face and possibly my life on the line! I worked up to this load. When I got close to max load for the book I began to go up a half grain at a time checking my pressures by measuring the base of my brass after I fired each round knowing I would stop when the base expanded .0005". As I worked up a half grain at a time there was little to no expansion and primers looked fine and no shinny spots on the base of my brass. I began at 83grs to get expansion and that let me know I was getting close. At 84.5 I had expanded .0004 and decided to stop. Now why did I stop and not go up until the base expanded to .0005? Well, I had already reached outstanding velocities of 3287fps on the average and excellent accuracy and saw no need to continue. This was a very cool lot of RL-22 and here are two targets shot with this load to illusrate why I stop and did not need to push any further. The first one is a group size of .334" and the second one is a group size of .1005"





Now to make my point, I tried a different lot of RL-22 and could only reach 81.3grs when the base of the brass had expanded .0004. This was a hotter lot of powder and did not have as good accracy as the other lot at the same pressures as seen in the following target which was a grooup size of .542"



I would advise anyone who is reloading to work up. Have you ever wondered why at times your favorite pet load when you bought a new lot of the same powder did not give you the same results. Well it is possible that your new lot is hotter or cooler than the last lot you used. Please do not use any of my load data stated above with out working up because your lot could be as much as 10% hotter than mine was. Now I know some will think this is just anecdotal experience. Please work up to max and start over with every lot of powder, just a suggestion but it might be worth consideration. My gunsmith said he fixes or throws away a lot of rifles and pistols that were destroyed or ruined by hand loaders.

What's the cartridge in your experiment?

Sorry that I did not mention it but it is the 300 Weatherby Magnum.

Some brands and types of powders tend to see more variability than others. Your not the first to run into this with RL-22. I hear more complaints about than it any other--probably in part because is is popular so a lot of people use it, in part because I think a lot of people tne to load RL-22 to the max because they are seeing higher velocities.

Using the expansion method to deterimine pressures has it's detractors.....you may hear about it

Casey

Yes, hodgdon has less variation but I have not been able in my 300WBY to produce the velocities and at the same time accuracy I want except with RL-22. I just try to get as small a group and high velocity under safe pressure conditions to give me as much advantage as I can. I just like to see what the best is I can get out of my load and stay within safe pressures

I have tried other powders like Hogdon and the variations were not as great but accuracy was not as good as RL-22. I know there are those who do not like the expansion method and I look for other things like flatten primers, shinny spots on bottom of the case, extraction. But been doing this now for 30yrs and have not had any problems.

When compared other lots of RL-22 and velocities achived on the average the Lot that produce the good accuracy and High velocity had a 10% spread in load difference than one of the other lots of RL-22 I just mention, but they had the same velocity. Pressure was reached quicker with one than the other. The test days were under the same basic conditions, both mornings were at 85 degrees and Humidity was between 90-95%. What I enjoy beyond manufactures recommendations is enjoyed by many who know that since there is lot variations we start 10% below book max and work up from there and sometimes we don't reach book before stopping and sometimes we are able to go beyond book.

Sounds like you have one of those rare barrels that can shoot faster than normal while simultaneously running at or below SAAMI maximum average pressures.

Would you mind disclosing more specifics about your 3300 Ft/Sec load? Brass, primer, bullet, throating geometry etc.

Thanks

Beartooth,

If your loads don't appreciate H4831, then another option would be to try MRP. It's more expensive. And it's availability has been spotty--so it would be good to lay in a supply of MRP



Casey

This is just about common knowledge , but it never hurts to re digest it once in a while. I don't load at max or evern near it.

Those who load to the holy grail that max velocity is the only way to go are the ones who usually have those funny looking split barrels after awhile

As mentioned above, how about Norma MRP.. It is supposedly R-22 only better. It is about $2.50 a pound more than r-22 at Powder Valley.

http://www.powdervalleyinc.com/

Case expansion is not a reliable indicator of chamber pressure or powder burn rate variation. The only time it is even a gross indicator is when using virgin brass. Once brass is work hardened from firing, overpressure is harder to see.

Another problem is that different brass lots can vary in hardness. A load can be 20k over max and extract easily and show no signs of high pressure. Soft brass can be sticky and show traditional pressure signs at 10% below max.

All powder varies somewhat in burn rate from lot to lot. Manufacturers try to hold it to within whatever their internal quality control standards are, but that number is just one of their choosing... 4%...6%...10%...whatever they "try" to achieve.

Pulling the trigger is the final Quality Control check.

TC

I have a process for my high volume loads that doesn't require working up as often. I will take 3 jugs (either 1# or 8#), mix them up real well and pour them back into their original containers. I then mark those containers with 'my' lot number. Makes life a lot easier but it probably wouldn't pay off for the casual handloader or low volume cartridges.

I have done the same thing.......


Casey

So the consensus then is that if I have a max load 58 grains of RL22 behind a 130grain accubond in a .270 winchester and buy a new lot, I had better back off to 56.5 grains and try it??? How is RL19, I just bought new lots of both RL22 and RL19. The 300WSM likes 65.9 grains of RL19 behind a 180 grain accubond and it also likes 61 grains of Viht N550 which is a max.

I just finished up a 5 LB keg of reloader 22 working up loads for a 300 Win Mag with 180 grain bullets and started a one pounder that was left over from the first RL 22 I ever had, the same load was way too hot with flat primers, ejector marks and velocities over 100 F.P.S.faster. It always pays to be carefull.
This powder sat on my powder shelf for years in the old paper can and I just do not know if it dries out and thus would give you more volume of powder by weight. This did not suprise me that much, but just loaded from a new can of RL 15 which has always been very consistent for me and got a suprise, The rifle is a 220 swift Rem. 700 26 ", 39 grains of any RL 15 has always given around 3810 fps with a 50 grain ballistic tip and shot between .180 and .250" from a cold barrell( 3 shots) This new can shows 3940 fps and groups are .500 or a little worse and primers are a lot flatter. So I guess even the most stable powders can vary enough to cause problems some times.

You might check out this I did this test on Rl22 and there difernt lots.
https://www.24hourcampfire.com/ubbthreads/ubbthreads.php/ubb/showflat/Number/1280771/page/0/fpart/1

This is a good post. It's something we all "know" but tend to forget on a regular basis. Something I noticed when working with a goodly supply of surplus military powder (IMR 4895) is that it tended to vary more from lot to lot than its commercial counterpart. The way I handled it was by making up some reference loads 5% below the load I'd worked up with my first lot of powder. When powder lots were changed chronoing loads with the reference charge and working up accordingly saved a bunch of time.

It has been really good to read all your responses and opinions as well as obvious knowledge. I am glad I posted what I did and I have gained from viewing you comments. Thanks

Three things:

One, just being picky, but the load change in the first post does NOT represent a 10% change in the powder. It's closer to a 4% reduction in charge weight. (And the alleged 10% variation doesn't say 10% of WHAT, but let's not quibble.)

Two, I know that case expansion measuring has its fans - I used to be one. But I think our good Denton Bramwell has pretty much destroyed it as a reliable means of even estimating pressure.

Three, allow me to once again offer up my Benchmark Load System.

When you find a load you like, prepare ten rounds of the exact same load, but with the powder charge reduced by 5%. That is your Benchmark Load (BL). Carefully fire and record all you can about the BL - velocity, spread, SD, and group as a minimum. Add pressure trace if you can.

Now, here's why: When you have to change ANY component of that load (new box of bullets, primers, brass, new powder lot...)the first thing you do is to prepare another test batch of ammo using the BL recipe. Let's assume it's the powder that changed.

Testfire it and record all the above. Compare it to your BL. One of three results will occur. A: the load will test slower/cooler than the BL; B: it will test the same as the BL; or C: it will test faster/hotter than the BL.

If you get B, you can simply duplicate your pet load and go happily on without a qualm.

If you get A, you'll have to work up again, but you'll know that you can start at the old pet load level and be safe.

The saving grace is if you get C, where the Benchmark Load tells you the old pet load may be dangerous with the new powder - AND YOU LEARNED IT WITHOUT FIRING A SHOT OF DANGEROUS AMMO.

well I was up to 58.6 grains of RL22 in my 270 from the old bottle before it ran out. It seems as if the more of the stuff I put into the case the smaller the group will get for some reason??? Now something about those little bitty 3 shot groups tells me I have to buy a freaking chronograph, and here I am just bare faced lying to my wife saying "reloading is going to save me money"....you guys are costing me way more money than my occasional trip to Walmart used to to buy a couple of boxes of "bullets"! (I am having fun though!)

cool, thank you for the info, that is good stuff.