Yes.. Is worded poorly.
the lighter seating bunch. Measure 2.195-2.196 to ogive.
the tighter seating bunch Measure 2.196-2.200 to ogive..
I after seating a hundred or so I could tell before measuring which were gonna be which. but seating pressure alone..
Chamfering could be an issue.. Although I am using a RCBS prep center and do inside/outside then case mouth brush internally.
But again, I am far from a reloading GURU.
How to most get consistent chamfering.. TIPS ?
thanks
Kyle
Sounds like you're talking about variation in seating depth rather than neck tension, although neck tension variance could be a reason for the differences in seating depth you have observed. Neck tension is measuring the diameter of the resized neck before and after bullet seating. If using a full length sizing die with a bushing, you can control neck tension by selecting the bushing that gives you an [empty] case neck diameter ~2 thous. under what it will be after seating a bullet. However, when testing different bushings to determine which one gives me the neck tension I want, I have found variation in neck tension of 3-5 thousandths between the 3-4 different bushings I tested. More importantly, the seating depths of those rounds didn't change by 5 thousandths like you're observing, probably because the force exerted by the ram/handle far outweighs the resistance of a few thousandths neck tension.
I think it is also unlikely that chamfering alone is responsible for the difference in pressure required to seat the rounds. Chamfering variation should only affect the initial entry of the bullet into the neck and unless the differences in chamfering between cases was absolutely huge, the variation in seating depth force you would feel would be miniscule. Further, the chamfered area doesn't contact the bullet, so unless you chamfered so deep you actually shortened the case neck length, the difference in neck tension should be due solely to contact between the neck wall and the bullet.
You might try taking 10-20 cases (enough to get a few each of both the easy and hard seating cases) and measure the necks accurately before seating a bullet. Then measure each after seating. This will tell you whether the neck tension is dramatically different on the easy vs hard seated rounds. If you have large variation in neck tension, the following are some possible causes:
1) resizing die - necks are inconsistently sized
2) uneven neck wall thickness in the brass
3) inconsistent annealing
FWIW - there are lots of ways to improve neck tension, but it's probably better to back up a step and try to figure out the underlying cause (if there is one) first, before making a bunch of [possibly expensive] changes. From your numbers above, the seating depth of two different sets of rounds are only differing by a max of .005". That means some differ by much less than that. That is really not an enormous difference, are you absolutely sure you have the calipers/comparator tool fully seated when taking a length measurement? I only mention this because it's easy to be just a tick off when seating the round in the comparator. Try measuring the same round 10 times in a row to see how much variation you get. If it's more than a couple thousandths, that's part of your problem.
Also, have you ever measured a group of your bullets base to ogive using the comparator? The seating die stem contacts the bullet at a point well above where you measure the ogive of a loaded round. Any lot variation in bullet length in that region can easily give you .005" difference between base to ogive length of loaded rounds because the seater stem pushes the longer bullets farther into the case. In other words, there may not be any problem at all with your reloading technique and/or brass prep. Measuring 10 or 20 bullets from that lot can tell you if this is contributing to your seating depth variation. FWIW - I've seen a number of recent posts at various shooting forums where people were complaining about length variation with Sierra 175s.
I would try these simple things first to see whether you actually have a seating depth issue, a neck tension issue, or possibly just simple variation in bullet length. If it's bullet variation, you can sort bullets into different length lots using a tool like Bob Green's comparator (
Bob Green New Products). Then you simply adjust your seating die for each different lot to get the seating depth you want.
If you find it's actually neck tension variation, the first thing I would recommend would be to use a neck expander die/mandrel (
SINCLAIR GENERATION II EXPANDER DIES | Sinclair Intl) (
SINCLAIR EXPANDER MANDREL - OVERSIZED | Sinclair Intl). Necks often get flat spots and dings from the ejector that may not be completely removed using a bushing-type full-length resizing die, because the bushing doesn't go all the way to the base of the neck. The expander die does a fairly good job of opening up and uniforming the neck so that the resizing die can do it's job better. Plus, the die/expander mandrel aren't hideously expensive.
Finally, a couple other useful tools for checking your case necks would be a concentricity gauge and/or a neck wall thickness gauge. These can tell you if the necks are not concentric and if the neck wall thickness varies, respectively. The concentricity gauge is also useful for evaluating runout of loaded rounds. However, in your shoes I would definitely spend some time measuring and/or comparing neck tension and bullet variation before racing out and buying expensive new tools. You can do this with the tools you already have and possibly find the cause of your seating depth variation, or at the very least rule some things out. Good luck with it.
