are you screwing the die in without a case in it?

Yes.

1. Yes
2. There is none. I don't believe it's an external problem. I think it's an internal problem. I screw the die mostly in... gap. I screw the die mostly out... gap. I screw the die anywhere in between... the same gap. It's like there's something inside blocking the neck from fully entering the die. I tried to take a photo from the top but difficult to see.

Perhaps you're trying to tell me something that I'm not understanding so here's what the Lee instructions say. "Screw the full length sizer in until it touches the shell holder. Then lower the ram and screw the die in 1/4 to 1/3 turn more. Raise the ram and tighten the lock ring finger tight." That's what I've been doing.

I bought the RCBS neck sizer from Midway. That should work, right? The shipping is only $5 plus rebate.
Sorry, missed your reply. That's my current theory but don't know how to test it. The only problem I see is that small burr seen in the photo.

I'm using Norma, Win, and PPU brass.

So what you are saying is you are extending the press all the way up, tightening the die down against the shell holder, lowering the ram, screwing the die in even farther down a 1/4 turn, tightening the lock nut, and when you raise the ram all the way to the top again, there is a gap?

So what you are saying is you are extending the press all the way up, tightening the die down against the shell holder, lowering the ram, screwing the die in even farther down a 1/4 turn, tightening the lock nut, and when you raise the ram all the way to the top again, there is a gap?

Yes.

Yes.

If all of your of your equipment is in good working order, this cannot happen.

Here is what you need to look for:
1. After installing your shell holder, raise the ram all the way up, measure the distance from the top of the shell holder to the top of your bench. Record your measurement on a piece of paper. Raise and lower your ram 20 times different times. Record the measurement each time. This measurement should be exactly the same each time.
2. With the shell holder still installed, raise the ram up to the full height, measure it to make sure it is at the correct height as you previously recorded, loosen the lock nut on your die and screw it all the way down until it hits your shell holder, do not move the die further, lower your ram and measure from your bench to the bottom of the die. This should be exactly the same measurement as the measurement from your bench to the top of your shell holder.
3. If the measurement to the top of your shell holder is not consistent each stroke then your press has a problem.
4. If the measurement from the bottom of the die to your bench is not exactly the same as the measurement from the top of your shell holder to the bench, then you are not adjusting your die correctly.
5. If the measurements are both the same as they should be, then stroke your press a few times until you see the gap appear. If the gap no longer appears then you have correctly set the die. Keep the die from turning and just turn the locking nut clockwise to tighten the die in place and keep it from moving.
6. If the gap appears then follow steps 1 and 2 to figure out which part is not staying in place by comparing the measurements you took previously with the measurements you get now. Which ever measurement is different from your original measurement will tell you which part is failing.
7. Let us know what your results are.

Checked the ram, linkage arms, pivot points?

since you're reloading 54R, i would neck size only.

someone correct me if i'm wrong, but i think the 54R indexes off of the rim.  because of this, full-length sizing could actually be a bad thing for brass life especially if your mosin has a loose chamber.

i suspect that your mosin has a very loose chamber since it looks like you're getting a noticeable bulge at the head (or at least it looks that way in your pic).

resizing larger rifle cases requires a significant amount more muscle when operating the press compared to 223, x39, and 300BLK.  i've never reloaded 54R, but i'm assuming that the amount of force required for resizing that cartridge is similar to 308 or 30-06.  i suggest removing the decapping pin and collet, lubing a case up a lot, and then Putin (intentional pun) some muscle into it.  the worst that could happen is the case gets stuck and you'll have to punch it out of the die.

If all of your of your equipment is in good working order, this cannot happen.
7. Let us know what your results are.

I agree. It's a head scratcher. The press seems to be "measuring" up. I don't have any problems with the other calibers although this is the largest of the four and the only bolt rifle.

since you're reloading 54R, i would neck size only.

That's why I bought the RCBS die. Should be arriving next Tuesday. Perhaps the constant FL sizing has taken a toll on the die. The brass seems fine except you can see how far down the neck the die goes.

i suspect that your mosin has a very loose chamber since it looks like you're getting a noticeable bulge at the head (or at least it looks that way in your pic).

If you're referring to the bottom of the case, this is as far as the FL die goes. There's about a quarter inch gap between the bottom of the die and the rim. I agree that the neck die will be much better on the brass.

i suggest removing the decapping pin and collet, lubing a case up a lot, and then Putin (intentional pun) some muscle into it.

What type of case lube are you using? did you try to size the brass without the decapping rod in the die?

What type of case lube are you using? did you try to size the brass without the decapping rod in the die?

Lee lube. Yes.

     Not sure about Lee dies but most RCBS sizer dies for bottle neck cases have a "Breather Hole" to allow for air to escape when the tight fitting die presses in.
If this hole gets clogged, you wont be able to fully press the die down against the compressed air in brass, especially larger cases.

     Check to see if there is a breather hole and if so, make sure its clear.
Poke through with pin, swab inside with patch and die cleaner or similar.
Just a thought

I found the breather hold underneath the locking nut. I assume it's able to breath, otherwise bad design. I now know what the thing that looked like a burr inside the die is. I cleaned it out thoroughly but there's still a gap. If I still have a gap with the incoming RCBS die, then I'll blame the brass. Don't think that's likely though...

I found the breather hold underneath the locking nut. I assume it's able to breath, otherwise bad design. I now know what the thing that looked like a burr inside the die is. I cleaned it out thoroughly but there's still a gap. If I still have a gap with the incoming RCBS die, then I'll blame the brass. Don't think that's likely though...

You'll usually scratch the casing if something is sticking out of the whole inhibiting the case and die to maryy.

I found the breather hold underneath the locking nut. I assume it's able to breath, otherwise bad design. I now know what the thing that looked like a burr inside the die is. I cleaned it out thoroughly but there's still a gap. If I still have a gap with the incoming RCBS die, then I'll blame the brass. Don't think that's likely though...

Using the correct brass ? 

I still trying to figure out exactly what you are explaining.

1. Die is screwed down till it touches off on the shell holder.
2.  Ram is retracted, die is screwed down another 1/4 turn and locked into place.
3.  Ram is returned (with no fired case) and shell holder touches die.
4.  Attempting to size a case, the ram and case advances into the die, sizing the case, then cannot be forced any more and shell holder plate is not touching the bottom of the die.

Is this correct?

Did you try and measure the over all length of the attempted to size case?

Is it overly long?  Is the top of the neck hitting the top of the die?

I still trying to figure out exactly what you are explaining.
Is this correct?
Did you try and measure the over all length of the attempted to size case?
Is it overly long?  Is the top of the neck hitting the top of the die?

Correct.
I'm using both 53r Norma brass and 54r PPU brass. The PPU brass requires a lite trim but not enough to mess with the die.

Using the correct brass ? 

I'm supposed to use brass? 

You'll usually scratch the casing if something is sticking out of the whole inhibiting the case and die to maryy.

I checked that too. No scratches on the brass...

Did you ever find no out what is causing this?

Did you ever find no out what is causing this?

Russians.

Did you ever find no out what is causing this?

The Chinese hacked into his press and installed malware, Trojans, viruses and steel eating bacteria. 

No, UPS transferred my delivery to USPS so should be getting the new die any month now.

No, UPS transferred my delivery to USPS so should be getting the new die any month now.

That's not funny.