Lee Loader

I seat and crimp with 2 different dies. This question is about seating my round nose bullets. With the flat nose bullets I use a flat insert and a conical insert with round nose bullets. The flat insert seem to be more accurate for COL, but the conical helps keep the round nose bullet straight. Everyone seems to talk in thousands of an inch when setting the COL. I try but can never get the same length twice. So, am I just being too exacting or not. I set my 9mm, 147gr, round nose bullets to 1.1600. Of course in doing this some turn out a little to short and some too long. Should I worry is the overall spread between the shortest and longest is 0.0085. Close enough? I know there is always someone out there that only deviates by .0001, but for the rest of us, is my .0085 spread acceptable? What are some of the spreads that you work with. Thanks
PS Using this longer length, I have to make sure it fits in the guns magazine and chamber carefully.

Sound very Very acceptable even if it's + or - either way.

Thanks. I worry too much. Even better, your right, it's about .0045 +/- and not .0085. I'll be looking for your posts. I'm sure I'll learn more.

0.0085" would bother me. If my brass was all within 0.00001" it would be different but I don't trim that close, especially with 9mm.

EDIT because at 4:00 AM I missed a 0 in my head....I thought we were talking 0.00085"

Just Curious, what bullet are you using? Are you planning on sticking with the bullet? If so, I've always wondered how Lee's custom bullet seating plugs work? It might be worth trying. The die set instructions detail how to place the order.

The +/- .0045" seems a bit high to me. In that you limit the high side, you talking a COAL variation of 1.151" to 1.160". I have not experienced a difference that high that would not require investigating. It sounds to me that you plug is not consistently engaging the bullet's ogive so your bullet's concentricity as it is being seated might not be as good as you think. The variation is also inducing a 2K PSI variation between the extremes.

I would pull the seating plug; they are designed for ogive contact, not nose contact, and examine how the plug mates with the ogive. Place a bullet upright on its base and then see if the plug balances on top of it with ogive contact. If not, you are not gaining anything with its use and you would be better off with a flat contact plug.

If the plug balances on the nose of the bullet, something is upsetting it as it starts to seat. You are probably using the Powder Through Expander die, expand a case, set it on its base and to see just how well the unseated bullet sits on it. If it is easily upset, expand the case mouth a bit more.

If none of this reduces the COAL, I would order the custom seating plug. It would be $8 well spent. See the bottom of the image below.

I am now working with a round nose plated bullet. I order .356 diameter bullets but still run them thru a .356 sizing die. I'm using a brand that has a ogive that lets me load long.
I have been working on the seater die. It's for round nose bullets and I have been shaping the plug for a customization to my bullet shape. I bullets sits well into the plug and the plug sits well on the bullet. I use the conical plug shape to make sure the bullet sits straight.
I also use an "M" die to get straight seating.
I have always wondered why the printed data shows the COL of a cartridge, but not bullet length. Different ogives produce different length bullets and using just the same COL will result in different seating depths and pressure variations.
So, thanks all, for the information. I'll work on getting a more uniform seating depth and keep it in the safe range of printed data and even check out FPS with a chronometer.
I guess it's still a game of keeping your variations in a safe range.
I can't wait to start loading in the +P range...NOT.

I am sure someone can do the math but my experience is that the further the distance from tip to ogive the greater the variation in OAL. A very small difference in diameter of the bullet where the inside circumference of the seating stem/plug contacts with the bullet will cause variation proportional to the steepness of the curve from this point toward the tip. When I first started reloading I was worried at the variation in OAL of my cartridges until I took a box of match bullets and measured them with a comparator. Lesser quality bullets showed even more variation. Your equipment, if properly adjusted, clean and tight doesn't change. It is the normal manufacturing tolerances of the bullet makers that is the problem.

So being the bored curious type I just repeated my measurement experiment on two lots of bullets. The first were 10 randomly chosen Berry's plated .355 HP 124 grain bullets all I believe from the same batch. The minimum length in the comparator was .461 and the maximum .463. 5 were .463 which says a lot about the excellent consistency of these double swaged bullets. The second batch were 168 grain Hornady .307 HPBT Match. Minimum length was .615 and maximum .624. Again all were from the same box.
Edit:
I am adding measurements of some PRVI bulk 139 grain FMJBT .263, minimum length was .731 and maximum .768. As an aside these shoot sub-moa in my 6.5x55 M96 and CG63. In fact they shoot better than the Hornady HPBT 140's which have a minimum length of .754 and a maximum of .758.