Dillon 550 catastrophic failure!!

Be aware that part has been redesigned. I think yours is the old style. The new one uses a different Link Arm Shoulder Pin. If your pin is a straight one, that's the old style. The new style is not all one diameter and has lubrication grooves cut into it. So you'll need one of those too.

Mine didn't break, but I wore out my link arms to the point they were flexing and the press was binding.

But yeah, that's quite the failure.
 
I'm sorry, so the part just broke/cracked from stress?? The title of the thread plus the fact you mentioned priming led me to believe a primer detonation caused this. But that's not the case, correct?
 
I am going to send in the press in to Dillon to overhaul it and make sure there are no other badly worn parts.

Randy

Good choice - Yes, you'll be without your press for a while and it'll cost you some shipping, but you'll get back essentially a brand new press. If you want to have some fun use a center punch to put a mark on all the major pieces and see how many you get back.

The Dillon mothership is about 20 miles from where I live. When I bought my 550B at an estate sale I took the whole press in to their showroom. I told them that I was the second owner, it was an estate sale press, and that I expected to pay for all the parts. The wouldn't hear it. The counter guys inspected everything from the powder reservoir cap to the used primer disposal tube and sent me home with a giant box of stuff at no charge. The only parts I paid for were the alignment tool and a new set of wrenches......along with a bunch of powder, primers, bullets, etc. :o

In my experience, the only company close to Dillon in customer service is RCBS. Both are fantastic.
 
I am going to send in the press in to Dillon to overhaul it and make sure there are no other badly worn parts.

Randy

Not a bad idea. It took me a bit to figure out my link arms were worn out. I kept them lubed but they were from the original 450 I had from 1982. Given the press had loaded well over 100,000 rounds over the decades I guess I can't complain.
 
More pictures of Dillon 550B dismounted....
 

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When you speak with Dillon CS, ask if they can replace the broken part with one that has the grease zerks.

My well used 550 was an early one that did not have the drilled grease holes in the ram mechanism. Even though I kept it clean and lubed per Dillon, it seized up on me one day. Could not get it apart. The replacement parts Dillon put on the machine all had the drilled grease holes.
 
I recall it possibly as a term from the northeastern US, meaning a "favor".

That's one definition for someone doing you right.
When I was in NYC, on leave in '68, met someone I grew up with.
Driving his Vespa while intoxicated, he hit the back of a City bus.
When he finished telling me about his face, teeth and scalp damage, all I said was ........... Solid.
He now lives in Florida and is one of many we avoid.
 
A common reason for metal failure is fatigue which leaves the broken surface rough, not crystallized. Metallurgists hate that term! This part failed due to low cycle fatigue, every stress cycle caused an incremental amount of damage to the metal. With enough cycles, the part fails as seen. A number of factors enter into the failure. There might have been a sharp corner which acts as a stress riser, extra friction raises the stress, and on press priming adds more stress in the opposite direction of sizing. Dillon constantly redesigns their equipment to add longevity. They radius corners to eliminate stress risers and the grease Zerk allows better lubrication and lowers friction.
Sorry for the long dissertation, the mechanical engineer comes out in me occasionally.
 
Dillion will take care of you. About 2+ years ago, the frame just below the dies cracked fully on my 550. Dillion had me ship it back & it returned with a new frame.
 
My 550B broke like the OP's after many years and countless thousands of rounds loaded. I called them and they sent me a new part for no charge. The press worked like new after that. It had been getting worn in that area, but I hadn't really noticed, as it was over a long period of time. Once I put the new part on, the difference was amazing.

Dillon is the best press with the best warranty and service. I have gotten many new and old reloaders to go with Dillon, and they are all glad they did.
 
update.....

Spoke with Dillon this morning....have send the entire press and broken parts as per their request....let them decide best course of action.

He said that it would take about a week after arrival.....

I wanted back yesterday...he just laughed...."spoken like a true reloader!!"

Randy
 
Beach marks are present in the break,, that means it has been working at breaking for a LONG time,

AND,, possibly, that part could have been broken before it got out of initial assembly.

That type break takes LOTS of cycles,,
 
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