Seating Depth Issue on LnL

by mutley 3/5/2023, 10:21 am

I got my Hornady LnL AP Press a couple month ago. Up until this point, I've been using it like a single stage press until I got everything dialed in and could get comfortable with a progressive press. And what I mean by that is, I would only run one case through all the stations at a time until I had a finished round, then I'd start another.

Yesterday I decided to start running cases through all the stations at once and I noticed that all of my finished rounds grew in COAL by .10 inches. My assumption is that one of the cases in another die station is bottoming out before the seating station fully seats the round. I tried running two cases through, one always in the seating station and then alternating the location of the other case, to see which station might be causing the seating operation to come up short.

It looks like its happening at the powder measure station but I can't figure out why. Its a Hornady Powder Measure with the PTX Expander. The throw arm is lifting just far enough up that it isn't contacting the measure housing and I'm putting a minimal flare on the case so I don't think the expander tube is bottoming out in the case itself. I suppose it's still possible it might be happening at another station and my test just isn't exposing it.

Here are my stations and dies:

Redding carbide sizing die (expander removed, all cases decapped in another press)
Hornady Powder Measure with PTX Expander
RCBS Lock Out Die
Dillon Seating Die with UniqueTech SWC stem for 45 ACP
Redding Taper Die (only taper, not seating)

I suppose I could just dial down the seating die but I figure that might just be masking a problem that needs to be resolved. I'd assume the press and dies ought to be seating to the same length regardless of how many cases are moving through the shell plate.

Any ideas?

by dannyd93140 3/5/2023, 11:37 am

Take all the dies out; then do one die at a time; resize remove the die, expand remove the powder measure; seat the bullet remove the die; crimp the round.

See if any of the stations are hanging up.

It's probably the PTX needs adjustment by the top and bottom screws.

by Dcforman 3/5/2023, 11:53 am

Also possible...

There is a minute amount of flex between the shell plate and ram. Generally, I have variance on the first few rounds to go through the press, and the last couple to come out. Having rounds in every station creates much more stability and consistency. I either always leave rounds in the stations between loading sessions, or when I have to switch calibers, make sure the first few and last few get used on the short line.

Dave

by DA/SA 3/5/2023, 12:00 pm

mutley wrote: I noticed that all of my finished rounds grew in COAL by .10 inches.

.100" or .010"?

by dannyd93140 3/5/2023, 12:05 pm

There's definitely some flex loaded 11,887 rounds of 45 acp on a LNL and had some variation but never that much; tenth of inch is a lot.

by mutley 3/5/2023, 12:43 pm

DA/SA wrote:
mutley wrote: I noticed that all of my finished rounds grew in COAL by .10 inches.
.100" or .010"?

Doh....

.010 is the difference I'm getting (not .10 as stated in original post).

by mutley 3/5/2023, 12:49 pm

Dcforman wrote:Also possible...

There is a minute amount of flex between the shell plate and ram. Generally, I have variance on the first few rounds to go through the press, and the last couple to come out. Having rounds in every station creates much more stability and consistency. I either always leave rounds in the stations between loading sessions, or when I have to switch calibers, make sure the first few and last few get used on the short line.

Dave

This makes sense to me. I'm going to tinker some more with the PTX and see if that maybe does it but I hadn't considered your point. Because of the flex in the plate, I could see where you could net a difference when there's equal pressure exerted across the shell plate vs when there's not.

by dannyd93140 3/5/2023, 12:57 pm

Take a marker and mark your PTX bar with a "T" for top and make sure you install it the same way every time; will save you a lot of problems.

by WesG 3/5/2023, 2:18 pm

I'll put my guess on the rd in the crimp die flexing the shell plate while you're seating the bullet. I kinda think I've seen the same thing.

by Boris_La 3/21/2023, 1:34 pm

I got rid of inconsistency and produce very good match 9mm ammo with following modifications:
1. Resize and decap on the separate press/step.
2. Shim the shell plate. This remove most of the flex and as a bonus you can feel the primer drag on the plate if not seated completely.
3. Use flaring die on the first stage. Stage 2 is powder measure no PTX.
4. Stage 3 is RCBS lockout die
5. Stage 4 and 5 seating and crimping dies.
The COAL is staying within 0.002" and ammo produced with good bullets is less that 2" at 50yard.
9mm is probably more difficult to achieve match accuracy, but some of those steps/mods may help you to reduce variables and can be used with different calibers.

by expendable 3/21/2023, 3:30 pm

Dcforman wrote:Also possible...

There is a minute amount of flex between the shell plate and ram. Generally, I have variance on the first few rounds to go through the press, and the last couple to come out. Having rounds in every station creates much more stability and consistency. I either always leave rounds in the stations between loading sessions, or when I have to switch calibers, make sure the first few and last few get used on the short line.

Dave

^^^^^^
This, I see the same on my Dillons.
I always try and make my final adjustments with all stations filled.

by RodJ 3/21/2023, 4:57 pm

Boris_La wrote:
2. Shim the shell plate. This remove most of the flex and as a bonus you can feel the primer drag on the plate if not seated completely.

Boris — can you elaborate on shimming? Trying to figure out where you put the shim(s) in relation to the shell plate, then washer and bolt.
thanks!
Rod

by Boris_La 3/21/2023, 10:13 pm

I don’t remember the source of this info, but it was a complete guide on LnL mod with links to shim set and pictures of installation. Shim installed on the ram top part, lowering the gap between shell plate and the base. Just search for LnL modifications including YouTube. It was while ago.

by blindshooter 3/22/2023, 2:57 pm

Here you go. Maybe the pics are still good. The shim trick made a huge difference for me. Press works so much better with less gap between ram and tight shell plate.
https://www.ar15.com/forums/Armory/How-to-tune-the-Hornady-Lock-N-Load-AP-progressive-press/42-414607/?page=6

by RodJ 3/22/2023, 5:15 pm

Thanks! Turns out I did the same thing but didn’t know it was called shimming. I need to see what kind of variation I’m getting. Been using a Star Universal for a couple years and the poor LnL has been idle.

by Boris_La 3/22/2023, 5:32 pm

Split washer to prevent bolt coming loose is not the same as shimming. The shims are set of very thin steel disks, that inserted to the ram top after it partial disassemble. That makes the threads sit deeper related to the ram's top and effectively the shell plate closer to the base (sub plate).
Update.
I think i have found the correct link for you https://www.ar15.com/forums/armory/How_to_tune_the_Hornady_Lock_N_Load_AP_progressive_press/42-414607/

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