My biggest issue with the LnL was the priming system. As it comes from Hornady, i think it is 90% of a great system. That last 10% is, or can be, a royal pain though.
My first problems came with the primer shuttle and the cam rod. The shuttle kept getting jammed up. Turns out the problem was the cam rod was coming loose. The nut in the picture below was the culprit. Mine would loosen up on occasion. I think i finally have enough torque on it that it will stay tight, but next time i mess with it i am going to double nut it. Check it every 1000 rounds or so.
The next thing is to polish the primer shuttle chase and the bottom of the shuttle itself. I also took my dremel and put just a touch of radius on the bottom front of the shuttle. This helps it slide through the chase better, and i think it helps prevent hangups on the primer itself.
The biggest thing, however, is the primer tube itself. I was having a lot of issues with the holding tube (small tube that actually holds the primers) start to come out of the tube holder itself. The shoulder helps it sit correctly, but the inertia of the ram going up and down combined with the friction of the primers on the inside of the tube would pull it up where the tube was not sitting in the holder. This would cause or allow primers to bunch up, get a little sideways or otherwise jam. It was a royal pain in the ass.
I bought a couple of extra tube holders (the part that actually bolts to the press) and epoxied a large primer tube in one and a small primer tube in the other. This keeps the tube and holder acting as one piece instead of two independent pieces and has completely eliminated my problems of priming issues. When changing from large to small, or vice versa, simply
swap the entire assembly out. It really does not add any time to a caliber change in my opinion.
Use some graphite and lube the primer chase, and every 100 rounds I take a small paint brush and clean the chase and primer ram real quick. I also bought some additional pickup tubes and will pre-load them with primers so that refilling the tube on the press while I am loading does not require me to stop for long.
None of the things i have done were major, took any time or special tools, but the small little tweaks made a world of difference in performance and reliability. No hand priming required anymore on calibers that get loaded on the LnL.
The other thing that I forgot to mention is to periodically inspect the primer slide - it is made of aluminum and the radius on the front side can get a ding or burr on it if you let it slam shut (guilty of that here more than once) when you pull the fiberglass rod out of the primer tube.
If the burr or ding is bad enough, it can keep the hole from being centered over the punch. I smoothed out mine once and have been careful to not let it slam home since then, but I've read about that happening on other forums enough to pay attention to it.
Buy the following:
2 each primer tube housing body (part #14 in your Owner's Manual, Production Part #398319A)
1 each Large Primer Tube (part #4 in your Owner's manual, Production Part #398358)
1 each Small Primer Tube (part #5 in your Owner's manual, Production Part #398357)
I ended up also buying some case retainer springs, another primer cam rod (bent my first one when the nut came loose), rotor o-rings and a couple of odds and ends to make it worth while. Always good to have some spare parts.
Primer pickup tubes can be bought in 3 packs off of Amazon
Since loading the primer tube is the most time consuming part of the process for me, I load 3-4 of them at a time up front, then run through them until they are empty. Every time I refill the tube on the press, I take a couple of seconds and brush any powder out of the primer chase, make sure the primer ram spring is clear and double check the allen nut on the case holder to make sure it is still snug.