My first attempt with reloading yielded poor results at the range. The accuracy of the load (.450 Marlin, 57 grains H322, 300 gr Partition, Winchester LR primer) was fine. What I shot was around a 2" group except for one flyer.

The problem is only 8 of 20 rounds fired successfully. My first thought is perhaps I didn't get the primers seated properly. I don't think the primer is bad. Is there anything else I need to consider that might cause this?

Any help would be appreciated. Thanks!

If your rifle is 100 percent reliable with factory ammunition, you are doing something that is affecting your primers. Most likely two possible causes.
1. you are not seating the primers properly. Primers should be seated either flush with the case head, or slightly (.001 to .003) below the case head.
2. You are contaminating the primers with some type of petroleum product, either oil or grease. Solvents and primers do not mix! If your equipment requires you to handle primers, be sure your hands are clean and dry.

Do you clean your brass & clean out the primer pockets & check the flash hole for any obstructions prior to reloading them??


Also what brand primers are you useing when you reload & are they stored properly??

I just wanted to say thanks for the tips. Based on Charley's tip, I went back and reloaded another 20 being very careful with the primers. Turns out the primers weren't seated properly before as I don't think I was getting them deep enough. I went to range and shot 12 rounds with no misfires. Thanks!

To 7mm.
I was using brand new brass this time and Winchester LR primers that are stored in the original box in a dry storage cabinet. I appreciate the tips.

Formula - the best advise I can give you is to purchase an RCBS hand primer for about $20. With this neat little tool, you don't have to touch the primers and you can 'feel' them bottoming out in the primer pocket.