Seating 9mm

I'm having consistency issues maintaining constant COL's.  For example, I set up for 1.120" and end up with 1.117 to 1.125 on the extremes, but most are within .001".   I've checked, rechecked, cleaned and tried everything to improve the situation but cannot seem to remedy it.   I have an RCBS Rockchucker single stage press bought new in March this year.  It doesn't seem to matter if I'm seating RN's or JHP's, seating before flare removal or seating and flare removal in the same press stroke.   Could this be a linkage problem?

Could be.  But .008 variation is a bit much.  What some rifle shooter do is seat halfway then turn the round 180 and then finish seating.  This would require flare removal and crimping as a third step.

Are you sizing the cases? Or flaring fired cases.

Is your die putting any kind of mark on your bullet? If the contact is not on the tip but on the sides you could get a large variance in seating depth.

are you sure there are no burrs on the rim/head and that the case heads are flat?

The AMU facebook site has monthly articles on handloading which are very good..


here's one form a month back or so about setting up your seating die to "remove" slack in the press and die.... They make an excellent point about taking slack out of the die threads(which are fairly course)

https://www.facebook.com/USAMU1956/photos/pb.251278279733.-2207520000.1441901548./10153726896299734/?type=1&theater

...

I  posted a quick reply to your questions while the above reply came in and I guess it didn't take...no time now but I'll answer the questions tomorrow.  Thanks.

Dave

Note the AMU Facebook series is NOT about pistol but about match rifle loading--a very different animal.
I would be more than willing to bet that if you shot them you would find that there is no difference in accuracy and almost no difference in velocity. If you measure some factory ammo, you will find that you are within their COL variation range.
In most cases, the variation is from variation in the bullets themselves or a poor fitting seating stem and bullets getting seated slightly crooked or, in some cases, a dirty seating stem that pulls the bullets up slightly.
Since you probably are not shooting <0.5MOA, these things just don't have any effect.

Noylj, you went and done it now!

I'm glad somebody else said it instead of me.

I agree with noylj. In the example you gave, your ammo is acceptable. All things in reloading are about tolerances.

OK noylj.  You obviously have a better handle on this (and maybe all) reloading issues than I have.  Just to answer the previous questions; I decap/size, clean, flare in that order.  No marks on the bullet and I use different seating punches for RN and JHP.   No burrs or anomalies appear on the case heads except the 1911 ejector dimple which has no different case measurement on or off the dimple site.  My next reloading session I will measure each round and record the readings to get an idea whether I'm getting a normal or skewed distribution.  thanks for your interest and helpful comments.

noylj wrote:..........
Since you probably are not shooting <0.5MOA, these things just don't have any effect.

Bigtrout,
we don't shoot pistol matches from ransom rests.

Robert, I'm not sure if your comment was in jest or a wisecrack.  I'll take it as the former.
First, I don't have a Ransom.  Second, my shooting from a rest is to get the best load I can for my RO so when I do shoot in informal club matches I know my loads are optimal.  To get there I must experiment and ask about variations I encounter and don't understand as I am a rookie 1911 shooter and a rookie reloader.  Pardon my ignorance.

Bigtrout, I think your methods are good. Measure everything you can and keep records. With more experience loading and testing you will know what is worth chasing and what is not.

And,

Keep records...

Well said, I so often commit to memory what powder charge is in those piles of reloads...

I keep a log of every loading session including its anomalies and have all my targets which have date, yardage, load configurations and gun modifications/sight adjustments.  Great reference material when the head-scratching starts and making a decision to "ask the forum."

Did you measure the OAL and diameter of your bullets and what was the variation?
Did you measure COL of some factory ammo to see what standard COL variation is?
Did you shoot your loads and see any accuracy variations due to varying COL?
The point is, worry about things that affect safety and accuracy, and don't chase things that don't have any real affect. Again, you are not even close to shooting 0.5MOA, so don't fret the "tricks" those guys use.
Does your seating stem exactly fit the bullet you are using? 
It should, if you really want "best consistency," contact the bullet only on the ogive. I have custom seating stems for SWCs and WCs that only touch the bullets' shoulders.
All die manufacturer's I have contacted are happy to make a custom seating stem if you supply a few bullets and some dollars.
There may be variables I am not aware of, but when I am seating, the only contact points are the base of the case is in the shell plate and the seating stem is contacting the bullet, so variation must be due to press variations or seating plug to bullet variations--I just don't see anything else.
One poster on some other site was having a much worse problem than you were and when "he" finally took some advice and took the seating die apart to clean it, he found a bullet wedged into the seating stem...

Good suggestions, noylj.  I am using the HP seating punch provided by RCBS in the 3-die kit.  I agree with your assessment of the source.  My caseholder is a positive stop for the case head and the punch is fixed by the die and punch locknuts.   The only other variable is the press linkage.  I've tried repeated seatings on the same cartridge which was .005 above the nominal COL and get no reduction in the COL.  If this really is a non-problem I'm letting it go as I see no benefit of "accurizing" the press.  Thanks all for your comments and help.

Dave