Question on effects of weather on reloading

Recon7 · January 26, 2013, 11:43 AM

Yesterday it finally came in the mail, 2000 shiny 124gn 9mm bullets. Today I was planning on doing a workup of a couple loads and shooting them to see how they do, but the weather is pretty atypical out here today. 58 and rainy in Arizona.

So here goes my question, will the loads I work on today behave very differently on a dry 110 degree summer day? And will it be drastic enough to care about if I am not loading up to max loads? My copy of Modern Reloading shows a starting load of 5.4gn and max load of 6.2 for True Blue with 124gn jacketed bullets, and I was planning on trying out 5.2 and 5.6 grains today.

AL45 · January 26, 2013, 11:54 AM

I am certainly no expert but I have read that humidity can effect how much powder is being dispensed and cold temperatures can effect how the powder performs. I live in New Mexico and even on rainy days it doesn't seem humid like it is in East Texas. I always weigh my charges so no matter what the weather I know what each case is getting. As a side note, you said the starting load in the manual was 5.4 grains, why are you starting with 5.2 grains. Just curious.

Recon7 · January 26, 2013, 12:16 PM

My lee pro auto-disk measures about .2gn lighter with this batch of true blue than the book says it should, but I still want to start with the same size aperture that is recommended in my book(.37cc). The next size up I estimate will weigh 5.6gn. It may be overly cautious, I doubt I would have any issues starting at 5.6 but I am still fairly new at this and will still enjoy shooting off 10 light loads in the process.

flashhole · January 27, 2013, 05:05 PM

I've only had one incident where I developed a load in cold weather and it proved to be over pressure in hot weather. It was a 223 load using Winchester ball powder. Mostly I use the Hodgdon extreme powders that are not near as temp sensitive. Just be mindful of what you have and always be on the lookout for high pressure.

Lost Sheep · January 27, 2013, 05:21 PM

Be sure to actually WEIGH the charges delivered by your measure (no matter what brand, Lee or Belding & Mull, verify the charge weight). Do this every time you start a loading session, at least\, and periodically thereafter.

Lee's Dippers and Auto-Disks are notorious for delivering less than the estimates in the factory-provided charts. Better than being over. Also, as the powder depth in the hopper varies during the loading session, compaction can cause the more or less powder to be delivered. Some brands of measure and some powders are worse in this regard than others.

If you get an extra disk or two, you can ream out the cavities to deliver precisely the charge you want. Be sure to indelibly mark any disks so modified.

If you find 5.2 grains does not reliably cycle your action, try stiffening your grip (hands, wrists and forearms, all). I found a load for my 45 with which I could induce a failure to cycle at will simply by relaxing my grip. It's useful for malfunction drills.

I have no experience with True Blue gunpowder.

Good luck,

Lost Sheep

January 26, 2013, 11:43 AM	#1
Recon7 Senior Member Join Date: December 10, 2005 Posts: 707	Question on effects of weather on reloading Yesterday it finally came in the mail, 2000 shiny 124gn 9mm bullets. Today I was planning on doing a workup of a couple loads and shooting them to see how they do, but the weather is pretty atypical out here today. 58 and rainy in Arizona. So here goes my question, will the loads I work on today behave very differently on a dry 110 degree summer day? And will it be drastic enough to care about if I am not loading up to max loads? My copy of Modern Reloading shows a starting load of 5.4gn and max load of 6.2 for True Blue with 124gn jacketed bullets, and I was planning on trying out 5.2 and 5.6 grains today.

January 27, 2013, 05:05 PM	#4
flashhole Senior Member Join Date: February 9, 2005 Location: Owego, NY Posts: 2,000	I've only had one incident where I developed a load in cold weather and it proved to be over pressure in hot weather. It was a 223 load using Winchester ball powder. Mostly I use the Hodgdon extreme powders that are not near as temp sensitive. Just be mindful of what you have and always be on the lookout for high pressure. __________________ ,,, stupidity comes to some people very easily. 8/22/2017 my wife in a discussion about Liberals. Are you ready for civil war?

January 26, 2013, 11:54 AM	#2
AL45 Senior Member Join Date: December 12, 2012 Posts: 754	I am certainly no expert but I have read that humidity can effect how much powder is being dispensed and cold temperatures can effect how the powder performs. I live in New Mexico and even on rainy days it doesn't seem humid like it is in East Texas. I always weigh my charges so no matter what the weather I know what each case is getting. As a side note, you said the starting load in the manual was 5.4 grains, why are you starting with 5.2 grains. Just curious.

January 26, 2013, 12:16 PM	#3
Recon7 Senior Member Join Date: December 10, 2005 Posts: 707	My lee pro auto-disk measures about .2gn lighter with this batch of true blue than the book says it should, but I still want to start with the same size aperture that is recommended in my book(.37cc). The next size up I estimate will weigh 5.6gn. It may be overly cautious, I doubt I would have any issues starting at 5.6 but I am still fairly new at this and will still enjoy shooting off 10 light loads in the process.

January 27, 2013, 05:21 PM	#5
Lost Sheep Senior Member Join Date: January 24, 2009 Location: Anchorage Alaska Posts: 3,341	Be sure to actually WEIGH the charges delivered by your measure (no matter what brand, Lee or Belding & Mull, verify the charge weight). Do this every time you start a loading session, at least\, and periodically thereafter. Lee's Dippers and Auto-Disks are notorious for delivering less than the estimates in the factory-provided charts. Better than being over. Also, as the powder depth in the hopper varies during the loading session, compaction can cause the more or less powder to be delivered. Some brands of measure and some powders are worse in this regard than others. If you get an extra disk or two, you can ream out the cavities to deliver precisely the charge you want. Be sure to indelibly mark any disks so modified. If you find 5.2 grains does not reliably cycle your action, try stiffening your grip (hands, wrists and forearms, all). I found a load for my 45 with which I could induce a failure to cycle at will simply by relaxing my grip. It's useful for malfunction drills. I have no experience with True Blue gunpowder. Good luck, Lost Sheep