Auto Breech Lock Pro OAL varies a lot

[James Hensler]

I read an older post from 1 ago and I am experiencing the exact same problem! My finished rounds OAL varies by exactly 10 thousandth or .010 Doesn’t seem like much but I shoot NRA Precision Bullseye Competitions. I drilled out the Seating Stem so that I am seating my SWC’s at the shoulder! The plug is not the issue. I put in in my Turret and it works as it should. When I adjust the die and get to my desired depth of .935 at the shoulder i can repeat it time and time again. Then when I fire for effect the measurement goes to 9.45 every single time. I read something about loading the plate and then run your rounds! Really? Is this still the best advice out there? I have checked everything! The shell plate the dies the whole machine! It’s 10 thou off! Help

[horseman]

Okay, this may seem to be a dumb suggestion/question but have you tried a "preset" of .925 and then run the press "fire for effect" (if I understand your meaning there). Would/does it then give you the 10 thou difference again to .935 which is your target? I don't know the press or it's abilities so just throwin' that out there..

[James Hensler]

Yes that is what I am doing! So the first 3 are short and the last 3 are short! Everyone between are where I want them.

[Tom Myers]

If your first and last 3 are short, it may be that your shell plate is flexing while not fully loaded. Lees instructions for setting up the dies are:
**************
IMPORTANT Lee die set users Screw the # 1 sizing die in until it touches the shell plate. Lower the ram, and screw die in 1/3 turn more.
**************
Theoretically , this should preload the shell plate to keep the OAL length the same for both the first and last three strokes.

If you are already doing this, then I can't think of any thing else that might help.

[James Hensler]

Well that might be something to look at
For SWC’s
Station 1 is expanding
Station 2 is powder charge
Station 3 is seating
Station 4 is Factory Crimp Die
For JHP’s
1 is powder charge
2 is bullet feeder die
3 is seating
4 is FCD

So as you can see I resize separately

[Guinearun]

I had the same issue. I removed and reset all my dies and used a sheet of paper between my sizer die. Holding pressure on down stroke it should drag but not rip, at least on my ABLP. Visually check other dies as well while pressured down? Hope you the best of luck, it’s definitely a new animal.

[Macd]

Another possibility. If your variation is +/- in a consistent pattern then I suspect a mating surfaces that vary in alignment as the rotating parts revolve against their respective mating surfaces. In this case probably a fixed surface. While lash in the threads and linkages may cause some variation, most lash is taken up when the press is loaded by the action of the lever. The problem surfaces when the distance in the lash changes depending on the juxtaposition of the mating surfaces. Even in precision ground gearing this is an issue for new assemblies. This is one reason why break in oils are used with magnetic filters to pick up the minute particles that are produced as the gears wear in. After a wear-in period the press may settle down. In the meantime a good high viscosity grease may help even out the variations.

I am not familiar with the press you are using so my comments are generic to any mechanical mechanism. Measuring lash variation may require a dial gauge set against the right surface. Sometimes figuring out how to set one up for a specific application can be a real puzzle. Just a caution, I would avoid any additional lapping attempt as dissimilar metals can create issues of uneven wear and galling which can actually exacerbate the problem.

[horseman]

All progressive presses are going to have some movement in the shell plate. The plates are held down in the middle by a bolt of sorts. If there was no movement they (shell plate) wouldn't rotate. There has to be a die on each side of the plate that is a firm "touch" to the plate to eliminate "rocking". If the press doesn't have that then there will be a change in OAL exactly as you describe. It's usually the last couple rounds off the plate because most of the time there is a sizing die in station one that touches the shell plate. Hence the statement "loading the shell plate". Sorta like "squaring" the die on a single stage press, sorta.

[James Hensler]

I am just not used it this because none of my Dillons ever did this

[kmw1954]

James as you can see this isn't like your Dillons so please do not expect it to be like them.

More info please. I see you are running two different configurations on this press with your dies. Are you seeing this same variation with both setups or one and not the other?

I'm running this press with both a 9mm and a 45acp die set and have tried RN, Flat point and TC. So far all have been stable to withing .005" on most bullet profiles. I have found a couple Xtreme that would vary like your .010" but if a change to a different box it goes away.

I too have been playing with an RCBS bullet feeder in station 3 and then seating and crimping in station 4.