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XL750 Priming question - loose primers

Len5E1

Private
Minuteman
May 3, 2018
81
14
Hello,

I'm trying to help a friend trouble-shoot some priming issues on an xl750. I have the same machine, dies, and caliber setup and I have no problems at all. We are even using the same remington once fired brass purchased from the same place. So onto the details:

At first he swaged a bunch of lake city brass and ran them through the xl750 and was having lots of priming issues and primers falling out. He chocked it up to over swaging with the dillon super swage tool. I told him to try the RP brass because it's not crimped just to get some rounds going so he primed like 20 cases and had at least one super loose primer. This doesn't make sense to me unless it's a bizarre coincidence because I've loaded hundreds of that RP brass without a hint of an issue and it leads me to believe there's something else going on. Sure it could have been a bad case but I'm still leading towards something else. The priming system doesn't appear to have a depth adjustment as far as I can tell but I haven't had to make a single adjustment to mine. Any opinions or suggestions?
 
What primers is he using?

Do either of you have a hand primer? or a different press that can prime... you can try to seat the same primers in the same brass and see if you still get the same problem.
 
What primers is he using?

Do either of you have a hand primer? or a different press that can prime... you can try to seat the same primers in the same brass and see if you still get the same problem.
That’s a good idea actually. He’s using federal small rifle primers I think and he does have a co-ax single stage he can try. Do primers expand a little when seated or do they keep their same diameter? I was just thinking if they are supposed to expand a little it could be the press but if they don’t I guess I’m not sure how the press would be causing the problem.
 
That’s a good idea actually. He’s using federal small rifle primers I think and he does have a co-ax single stage he can try. Do primers expand a little when seated or do they keep their same diameter? I was just thinking if they are supposed to expand a little it could be the press but if they don’t I guess I’m not sure how the press would be causing the problem.

If anything the primers get a tiny bit smaller as they're wedged into the primer pocket. It should be a pretty tight fit.

The 750 uses the same priming system as the 550, which is what I use. You can definitely adjust the depth of the primer seating, but usually it gives you plenty from the start.

Are they seating below flush?
It does not take a lot of force to prime on a 550/750 with all the mechanical advantage you have.
 
I would think bad brass or bad primers. Not sure how the press itself would cause a lose primer?? Maybe over swaged, But on the dillon 600 when i was learning to set it up, when i over swaged, it didn't make loose primer pockets, it shoved the bottom of the primer pocked closer to the primer end of the brass, Then was not able to fully seat primers depth wise.