Gentlemen, please be careful... The US Department of Transportation does not play games.
The training requirements for shipping hazardous materials including low explosives such as bulk smokeless gunpowder and primers are found in
Combined Federal Regulations 49 (CFR 49). The following is from an online training website:
https://www.oshaeducationcenter.com/hazmat/dot-hazmat/?msclkid=e56d912ca85b1e2947fcf7fe7cbff043
DOT HAZMAT shipping training is an annual requirement.
"All workers who handle or ship hazardous materials (HAZMAT) must complete DOT HAZMAT transportation training within 90 days of their job start date or a change in job duties.
DOT hazardous materials regulations found in 49 CFR 172.704 Subpart H/HM-181 dictate the training requirements for approved HAZMAT training.
Under
Section 172.704(d), employers (or an individual shipping HAZMAT) must create and retain a record of current training for each HAZMAT employee. The DOT HAZMAT certificate of completion satisfies this recordkeeping requirement.
The minimum requirements for DOT HAZMAT transportation training are found in 49 CFR 172.704 Subpart H, also known as HM-181."
Otherwise, without DOT HAZMAT certification one may ship via UPS small arms (loaded) ammunition and primed cartridge cases. But if primers are in their factory packaging, they require shipment paperwork signed by a HAZMAT certified individual.
https://www.ups.com/us/en/support/s...s-materials-guide/how-to-ship-ammunition.page
So, your friend in Pennsylvania cannot find large rifle magnum primers for loading his 404 Jeffery but has the cartridge cases. You have LRM primers but live in Arizona. You may NOT legally ship him a box or brick of primers. He may however ship you empty cartridge cases (and the reloading dies if you don't have a set). Then you may prime his cartridge cases and return them to him in in a box properly marked for small arms ammunition with a 4" HAZMAT symbol. I always put a HAZMAT diamond on two sides of the package.