Dillon 550 vs LNL AP (my thoughts)

Disfunctional_Engineer

Sergeant of the Hide
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Minuteman
Jul 27, 2020
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I figured I would put my thoughts and opinions out there (for what they are worth.) I own both presses and have loaded .38/.357, .45 ACP, 223/5.56 and 9mm on the Hornady and 9mm/223 on the 550. This is my opinions on a few subjects:

-Auto vs Manual indexing
The Hornady is going full swing is noticably faster than the Dillon. I've never measured it but it's there. By its self it would probably not be enough for me to choose the Hornady exclusively based on that. The exception would be production of massive amounts of a caliber. It may be a fairer comparison of the LNL AP to a 650 or better press tbh. The Hornady has had some binding issues on a rare occasion but that ususally means its time to get the press apart and clear out the junk.

-mid loading case removal
The LNL AP uses a spring wire setup for case removal. The Dillon uses brass "tacks" that hold the cases in. The advantage of the Hornady is you only need one spring and it covers all calibers. The Dillon gives the advantage of not having to work the spring all the time if you want to load 2 stages and pull the cases out at the third for some reason. I would call this personal preference.

-Caliber conversion
I am going to break this out into 2 areas. The first is strategy and the second is functional quality.

Strategy:
Dillon and Hornady go about 2 very different ways to deal with caliber conversions. Both have a shell plate swap, priming system swap (if needed) and then a die swap. The dies in the Dillon are pulled out together along with the powder measure. These complete units are then typically stored on a stand instead of being broken down into individual components.

The Hornady has dies in individual bushings that are held in with O-rings. The powder measure is the same way. The Hornady has a fifth station that the Dillon lacks as well for a powder cop or lock out die. I feel that the configuration of individual dies offers convenience in the right circumstances. As an example you could have multiple seating dies for various loads and come back to them. Adjust (or even better buy spare powder measure metering rods) your measure, change the seating dies and you're loading for a different bullet type/weight. The Dillon doesn't accommodate that as easily especially since the dies are tight in the 4 stations. Some people say that the O-ring system allows "float" of the dies although I don't know that one way or another. If you desire this flexibility the Hornady is easier IMO. If you desire quick changes the Dillon wins.

Function wise, the Dillon is the clear winner in my mind. Here's why:

The Dillon shell plate system is in my opinion superior if only for the reason that there's a set screw in the ram to hold the bolt in a specific position. Every so often I think about trying to figure out how to retrofit the Hornady to such a system. You have to crank down on the screw pretty hard and it will still loosen up now and again.

My LNL AP has had issues with the powder measure staying in the press. I've had a few boxes of .357 mag where I didn't have any powder in half the cases. The reason why is that the powder measure will twist and start popping up which you may or may not notice. It's a well known issue that Hornady will supply a fix for. I ended up taking a piece of sheet aluminum that I refer to as a "big comma" and punching a hole in the middle of it. I use that to keep the measure from twisting and subsequently unseating. I will probably change this over to a set screw at some point.

You don't twist the dies in the Dillon. I think this is a better setup unless you're running screw retained lock rings. The ones with my Lee dies would probably be fine in the Dillon tool heads but they're not a good choice for the LNL AP because you twist them out some times when you try to twist out the die bushings.

It's getting early here so I'm off to bed. Next go I'll cover priming and powder measures as included as well as a few final thoughts. If you've got questions ask away.
 
Put a split washer under the Hornady plate bolt and it won't come loose.

As to the powder drop twisting loose I dunno what that's about, are you using the little case flaring flanges?

I'm only loading 223 on mine for practice ammo but it's humming along pretty smooth at this point.

If you get any binding in the case feeder assembly you probably need to put lube between the rotating pieces. I had all manner of issues till I greased the ramped shell dropper that the pushrod actuates, now it hums like a sewing machine.
 
Overall I tend to use the powder through expanders like you're talking about for pistol ammo. Some people have the problem, some don't. My buddy who loads up tons of 9mm (I would guess he probably has 30K+ on his) had the same issue. I believe I have seen the issue with 223 as well though. The thing about rifle cartridges is they tend to push the measure up higher so you notice.

I do not have a case or bullet feeder assembly on mine. That would be fantastic but hey there's other priorities in life. The binding I have experienced has been for the shell plate rotation. As I said though pulling it apart and cleaning it fixed the problem. I typically use some sort of light oil here and probably need to transition to a dry lube and that would be a more permanent fix.
 
I used lithium grease. If the plate binds when it tries to rotate that usually means either a primer wasn't knocked all the way out or wasn't seated properly and is protruding into the spent primer tube or the shuttle as the plate tries to index.

Had that happen, twice, and broke two pawls when I first set it up because I didn't understand what was happening, out of spec Winchester brass primer pockets. 🙄
 
Have had that happen but in general I consider the failure to decap typically the fault of the dies not so much the press.

Never broken a pawl thankfully. Apparently they are adjustable as well? I don't recall ever having anything needed their either. Maybe I was lucky on that front.