I've been reloading for many years, but mostly pistol cartridges like .45 ACP and .44 Mag.

I have added .30-06 Sprg and .243 Win to the list, and things were going fairly well until I noticed slight variations in cartridge headspace length with the Wilson gauges.

It turned out to be the shellplate. This has to be square during the stroke. If it isn't adjusted near "almost too tight to turn", it can walk a little on the ram, and this will affect cartridge headspace length (makes it larger.)

This may be obvious to most, but it caught me by surprise so I thought I'd share it.

(As .45 ACP, .30-06 Sprg and .243 Win all use the same shellplate, I could simplify my life if I just didn't have any .44 Mag... )

Hi if this happened to me I would send this same e-mail to dillon and see what they say.

I only load pistol and .223 on my 550b so I have no ideas for you.

Let us know what they say if you have time.

Thanks...........burgie

I sent an email to Dillon, asking if this problem had been reported by others. I will definitely post their answer.

The instruction manual does say to tighten the center bolt until the shellplate won't move, then back it off a little. Apparently I was backing it off too much.

If you have any visible "rocking" of the shellplate when you press on opposite sides with your fingers, you are probably going to see more variation in cartridge headspace length than you should. The press is capable of doing better, if the shellplate is adjusted so there isn't any slop.

While the effects aren't noticeable in pistol calibers, they are in bottleneck, so you might see this in your .223 loading.

I've been using Dillon for MANY Years now and Load 28 Calibers Pistol and Rifle .

I've never experienced trouble with anything other than the Primer slide !.

( I wore one out Large primer I believe ) they sent a new one NC along with several replacement pieces

pertaining too the primer slide set up . I never asked them for any of it , they just sent them .

Here is what I do ; stroke it so ram is up loosen Allen keeper screw way out . Pull the shoulder bolt

use some decent grease or lube, now lube the wee wee out of it the ball and spring under the detente ball .

Put it back together tighten the bolt down until it won't move , now using the Large Allen wrench

for the shoulder bolt back it off until the the shell plate turns with out binding . HOLD it there

and tighten in the Small Allen keeper screw . I avoid lubing where the keeper screw goes as a precaution

to it holding fast . Should be GOOD TOO GO !.

Almost forgot there is a wire retainer spring that keeps the casing into the shell plate holder ,

You may need to adjust it. It's held with a flat head Allen screw so as too slide in or out for different

case head rim Dia.

I noticed this the first time I used my 550B. I make the shell plate as snug as I can & still make it turn. I do not load rifle rounds on it, some day, but I do load for 10 pistol calibers on two of them.

I feel kind of silly. Until I got into bottleneck reloading and the Wilson gauges, I just wasn't aware of the effect of the shellplate adjustment. I had been backing it off too far, so there was a little play.

No reply from Dillon, yet. Their instruction manual does describe how to adjust this, but backing off "a little" is sort of subjective.

Reply from Dillon, after I reported my trouble and asked if it was common enough to rewrite that section of the user's manual to make it a little clearer -

quote:

I’m sure a few others have had a problem with this, but not enough for a rewrite. Most with problems just didn’t put the die down low enough combined with not using a headspace gage or reading it correctly.


Thank you,
Dillon Precision Products, Inc.

So, perhaps some day someone will stumble into the same hole I found, and the "Search" function will help them find this...