Hornady LNL-AP: COAL is 0.010 longer with brass in all stations - why?

[IMtheNRA]

Today I began loading 9mm ammo with Winchester 115-gr FMJ bullets. I am using my new Hornady LNL-AP, all three Hornady dies, and an RCBS Lockout die. I am NOT using a powder-through expander or a seperate crimp die.

I adjusted the micrometer stem on the seating die to get my desired COAL of 1.135 and made a few test rounds. All was well, with a COAL variance of +/- .002, which I thought was acceptable. I set the seating die to very slightly crimp the round, which seemed to do a great job removing all the residual belling of the case mouth. I can feel very slight "springiness" of the press handle, which i usually associate with crimping action.

As I shifted into production mode, and had brass in progress on all stations, I measured the first few rounds to be ejected from the press. All were approximately 0.010 longer than the test rounds that I made one at a time. So, I adjusted the micrometer seating stem down to compensate for this, and kept loading, with the desired COAL +/- .002

Why was this adjustment of the seating die necessary? I know there is more work being done by the press, as I need to apply more force to the handle, but I still "bottom out" the press handle at the end of each downstroke.

Is one of the dies screwed down too far and is interfering with the downstroke of the handle, causing a false sense of "bottoming out"? What do you think is the first place to look?

Or, is this a normal condition and I should just make the seating die adjustment each time I switch between one-at-a-time and production modes?

 

[Navy joe]

Could be the seating die is bottoming, or the press is flexing. I've noticed small variances on a 550B doing the same as you mention. I usually set the pres by making dummy rounds with brass on all stations and no primer or powder loaded. I keep the dummies for dry practice or break tehm back down.

 

[Roccobro]

I think it may be the forces on the plate and deflection. When you have every station "working" a round (at least the ones you have chosen to use), you will have the most accurate representation of a round that will be churned out at full throttle.

Justin

 

[Idano]

IMtheNRA,

Here are few things to check:

• Did you set up your bullet depth with your resizing die in the press?
• Check to make sure that micrometer on the powder measure is not hitting the cast housing. There should be at least an 1/8" or more of play when charging a case and the ram is all the way up.
• If you are using military brass or a mix of swage all of your military brass. Military brass with improperly swagged pockets has been the cause of 99% of my with this press and other progressive presses. Since I have started using the Dillon Super swage i seldom have a problem and when I do it usually is an operator related issued.

I am sure there are few other possibilities but these three come to mind since they are the most common. If everything is set up correctly you should see much if any variance between single mode and progressive.

 

[IMtheNRA]

Guys, thank you for the ideas. After reading this thread, I experimented a bit and found that I must have a case go up the resizing/decapping die in order to maintain consistent COAL. Taking cases out of any other station did not have any effect on COAL.

It appears that from now on, when setting the seating stem micrometer, I must have a case up in the sizing die in order to have repeatable results in production mode.

 

[Idano]

IMtheNRA,

There shouldn't be any noticeable variance if the resizer has casing in it or not.
Check your decapping mandrel, it sounds like it may be adjusted too far down. If it is adjusted too far it will hit the bottom of the case. I usually adjust the decapping pin by backing it out then run a case into the die and manually screw it down until it just pops the primer. I mark that spot on the threads then adjust it down until it hits the bottom of the case and then back it out half way back to my previous mark. This way I am sure it will knock out the primers but not bottom out on the brass.

 

[DaveInFloweryBranchGA]

One thing one must always realize when setting up dies in a progressive:

What you do in one die tends to affect the others, at least to some small extent, so once you've set them all up, it pays to fill up the shellplate with cases, then double check everything BEFORE you add powder and primers. That way, you can correct little items like this that like to show up.

Regards,

Dave

 

[IMtheNRA]

Idano, that's a great insight. Your theory makes a lot of sense.

I'll check the decap pin in the morning. I remember adjusting it down after an incomplete decapping, so I may have extended it too far.

Thanks a lot!!!

 

[Walkalong]

I size my cases on my Projector, then prime with my RCBS hand primer. Then I run everything through the Projector to load. Not priming or sizing while loading helps O.A.L. issues a lot.

 

[SDefender]

With my LNL and doing .40 S&W, with only a single case in the seater station, it will vary ~-.005" from a press full of dies and cases. It will vary ~.-003" with cases in the last two stations. Consistently. Can consistently vary 0 to -.001" with last 3 cases in stations.

So overall, mine is very consistent until the last two cartridges of the session. In particular the last one will vary enough I need to fix it and possibly the next to last also.

I did not realize all of this until I started reading the COAL issues last week. Thanks to the OP. Has sure made my life easier now and no more pulling out the hair. Now just have to figure out if the .45 auto will react the same. My guess is will as it is probably a flexing issues of the press.

 

[Jetsurgeon]

Usual Press Flex..... Like others stated, have brass in all 5 positions when setting up dies.

J

 

[1911NM]

Ditto here, just flex. When I am setting OAL on my LNL-AP, I set brass in the resizer die also. Gives the consistancy. <shrug>