Seating Depth variation on Dillon 550

[Carphunter]

I just figured out that I'm getting a seating depth variation on my 550 when doing my 10mm pistol rounds...haven't checked any rifle rounds.

When developing loads, I often walk a case around the press on it's own... nothing else on the press. When I do this, I get a seat depth of one length.

Now, when I have cases in all stations, I get a depth that leaves me with a longer oal by a couple or a few thousandths (.02 to .04 difference). It appears the other station that matters the most is the sizer/decapper.

I'm guessing the resistance of the sizer capper is enough to either hold up the press to stop that last couple o thousands push, or the tool head plate gets held up a tiny bit.

Just wondering if anyone else has noticed this.

To alleviate the problem in the pistol loads, I'm going to start setting the seating die only when I also have a case in the sizer.

 

[dmftoy1]

Yup, I've noticed a difference between using it 'turret' style vs using it as a progressive. (about the same as what you're referencing). I bought of those kits from UniqueTek but haven't had the time to experiment with it. (It's been hanging on the wall for 2 years now. : ))

I tend to just keep all the stations full when adjusting the dies. FWIW.

Have a good one,
Dave

 

[Carphunter]

Just read up on that kit... interesting idea... but would take me some time to get it running.

I'm going to do like you did and just always keep the press full when setting it up for now

 

[Slamfire]

Now, when I have cases in all stations, I get a depth that leaves me with a longer oal by a couple or a few thousandths (.02 to .04 difference). It appears the other station that matters the most is the sizer/decapper.

Ok you are able to measure the phenoma. No let me ask you a question, does it matter? If it makes a difference on paper, or pressure, or function, than it matters. But if it does not, (and I doubt that it does), why bother?

 

[30Cal]

Is your decapping pin set too deep?

 

[Bitswap]

How are you determing the variance? I hope your measuring on the ogive of the bullet rather than the tip. And, are you loading swc vs rn vs hp?

A good seating die will purchase on the ogive of the bullet and your measurements should be the same. Nothing is perfect. Even the most expensive bullets have variances. A few thousands in a pistol is nothing to worry about.

I find it hard to belive you'r not seeing a varinace on a 'single cycle'.

 

[cpttango30]

I would raise the decapping pin to where just enought of it stick out that it knocks the primer out. If that didn't help then put a case in all stations and crank the seater die down .02 or .04"

 

[zxcvbob]

Are you using cast bullets? I don't have a Dillon, but it sounds like your bullet seater doesn't match the bullet profile. With jacketed bullets, it doesn't seem to make as much difference.

 

[Mike Franklin]

Call Dillon, what's the point in having a tech on call if you don't use'm?

 

[Bitswap]

+1 on what Mike said. Blue will help you figure this out.

 

[redneck2]

Yo, chief...

you've got two different things here. You said

few thousandths

but you wrote

.02 to.04

which is hundredths.

Which is is?? If it's thousandths, you're getting way too concerned about little to nothing. OAL is pretty much meaningless, as the points of the bullet vary. As noted previously, measure to the ogive. My best rifle reloads vary +/- .010 OAL. Even +/- .002 to the ogive probably means nothing on pistol.

 

[HRT]

Bullet ogive/nose diameter and other rounds in the press make a big difference, A flat point seating plug has been more consistent for me with both RN and FP bullets. For perspective a normal sheet of notebook paper is 0.003-0.004". Unless you are repairing stuff for the .gov a few thou on oal is nothing to worry about. Now a few hundreths is getting to be something meriting somme additional attention.

 

[Carphunter]

you're right... it should have been .002 to .004.

This may or may not matter in pressure, velocity in my particular loads.

It's just a variance I'm trying to alleviate.

For rifle seating, I do check my ogive lengths with a comparator. at the moment, don't have a .40 cal comparator.

for practical purposes, I did find by just having a shell in the sizer/decapper, it took out the variance (and my decapper is not bottoming out).