Ecinomical load development in a component drought.

Greetings All,
Powder burning speed varies from lot to lot of the same powder. Sometimes this is minor but not always. I almost got caught out by a big change in the speed of AR2209 a few years ago and have pondered about it ever since. One of the things I learnt is that you need to check the speed of every lot of powder you get. The good news is that you don't have to go through the whole load development process again.
My current process is to load a couple of rounds two grains under my previous load and chronograph it together with my old loads. If the velocity is much the same then all is good. If not then an adjustment of the load is needed to achieve the same pressure and velocity. I find it easier to use a graph like the one below.
Attachment 188760
The rifle is a 6.5x55 Tikka T3. Also included is data for my M38. Load data for the 6.5x55 is patchy and conservative so I had calculated what should be possible based on case capacity. I also plotted the data for AR2209 and AR2213SC from Hodgdon and Nosler. As you can see the old lots of AR2209 are like the Hodgdon data and the Nosler loads are in line with the new AR2209. The plotted lines of powder charge and velocity are quite straight and parallel to each other. If you have your old load plotted like the Hodgdon data and your new load produces more velocity then you can use the graph to estimate the powder charge correction needed.
I have often wondered why the powder speed changed. First I thought that this could have been when ADI became the supplier of H4350 about 1992. Checking published load data for H4350 prior to 1992 shows no significant difference so we can scratch that one. My old tin of AR2209 stamped 1998 is the slow stuff. I turned up a post from a handloader in the US reporting the change in 2002 so around 2000 is a likely date. The why is a different matter and frankly I don't know. This change is not limited to one can or lot as published data from Handloader in 2007 matches my results for my current can purchased in 2019.
I use these graphs more and more. A few chronographed mid loads tells us where we are and a likely charge to develop maximum velocity. Saves a truckload of components.
Regards Grandpamac.

Good approach @grandpamac - lots can vary, I am comfortable adding a low tub of powder to a new one if the lot numbers are the same, but not otherwise (even though after a good shake I doubt there would be a discernible effect).

As you know I'm getting back into reloading. I've never had a chronny; always just started at minimum and went as high to max as I felt safe til accuracy suffered. Usually just settled for the most accurate, well powered load.... Now everyone talks chronny's and ladder testing etc.... I'm soooooo far behind the 8-ball! I thought this time to start at a mild load just under halfway between min and max with the Howa 223 and 308, and at minimum for the SMLE 303 as a way of saving components. Sound sensible???

bublefoot...that is more than sensible,it is in fact what some of us do all the time,pick a charge weight somewhere in table that isnt maxed out and just load some and see if they shoot accurate enough for intended usage,then stick with it.....chasing every last fps isnt my cuppa tea and for my 99.9999% shooting under 300 yards I dont actually NEED to group better than 1-2inches anyway....

Have done that with my last two loads @bumblefoot, probably a fluke but got the 150g oryx shooting in 12 shots and the 65g sierras in 7 shots. Followed up with some more to check and I'm happy. Will run them over someone's chronograph for interests sake at some stage. I think they'll both be on the slower side but my brass will thank me and the victims won't know.

Greetings Bumblefoot,
I have not loaded a start load for over 40 years. Usually start with a mid load. I don't work up 0.3 grains at a time either. These have always seemed like a lot of busy work and wasted components to me. Charliehorse has the right idea in running your finished result over someone elses chronograph to check where you are, prefarably before you get to max. You are on the right track. I have found the Hodgdons / ADI data generally very good. A lot of my loads are under max.
Regards Grandpamac.

@grandpamac When I was loading for the 270 many years ago my best load was .5 grain under max using H4831, Regarding mid loads; I'd say a mid load for the 303 would probably be about the equivalent to the factory stuff as a guess? I'll go 1/3 of grain with the SMLE though,

When I loaded for the SMLE I used IMR4895 with a Hornady 174gr RN, I used just over minimum as it was a bail gun for pigs. However I did head shoot a fallow at about 150m with open sights with it and that load.... Trajectory was probably artillery-like... The word "fluke" comes to mind... ;) But I was young and dumb...

I've found if you do some research and read all the different reloading forums out there and see what majority of reloaders are doing with any given caliber, that's what's likely gonna work for you.

there was thread on here some time back re whats your go to load for .223 it was surprising how close ,give or take we all really are.... 24-25-26 grns AR2206h behind 50-55grn pills seemed to come out on top as most used....and a lot of other powders were very similar...