9mm on the Dillon 550B....

by Gunner , St Louis, Sunday, June 23, 2024, 13:18 (151 days ago)

I love my 550, have loaded over 35,000 rounds on it, all big bore pistol rounds, 41 Mag and 45 Colt. My Dillon Square Deal is used for 45 acp, almost 30,000 rounds on it, no issues with either, until now.

It the past year I have bought several 9mm guns, including a CMMG Banshee AR, suppressed it is the most fun gun I have ever shot besides a full auto, so I decided to start loading for the 9mm. I wanted a Square Deal in 9mm but none were available, including from Dillon! I didn't want to mess with converting my 45 Square Deal so I bought dies and an conversion kit for the 550, and that is where the issues started.

Primer sitting that is, especially shooting a suppressed 9mm pistol, even with the booster installed, a lighter recoil spring solved some of those issues but I was still getting misfires. Checked the primer seating arm position, off 1-2mm, re-centered it, re-cleaned the priming system but am still having issues with the primers not seating correctly.

At this point I am only loading sub sonic rounds as I have 1,000+ rounds of factory ammo. I have an after market extended primer arm plate with roller bearing installed on the 550, even operating the handle slow I get primer flops, short seated and crunchy seating at times. I know I am a little biased and wanted a Square Deal and didn't want to use the 550 with it's long stroke handle throw but I know there lots and lots of reloaders using the 550 for 9mm.

I have been reloading since 1988 and have NEVER had a round of ammo not go bang until the 9mm and it is frustrating me, anyone have any advice or suggestions????

Gunner

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