bullet seating

A

AL PALMER

Inactive
I have RCBS seating dies.After I set the die at the seating depth I want and start seating several bullets,they are inconsistant when I check the lenth.I use nosler or sierra bulets.The the die grab the bullet at the ogive or the tip of the bullet.Sometimes there as much as four thoulsant plus or minus off.Where does the problem come from.Thanks for any answers.:confused:
 
The Ogive of bullets is not always the same - even in the same lot. When you switch to a different manufacturer there is a lot of difference. If your seating plug is hitting the tip of the bullet you need to clean the punch or drill the center deeper to get the clearance for the tips.

I have done this on a couple of punches but I also found that a call to RCBS will get you a punch in the mail for free.
 
Thanks for the answer.So you are saying its in the inconsistancy of the ogive.Icheck the plastic tip and they don't seem to hitting the die. Any way to correct that problem.Thanks for any reply.
 
AL PALMER
I also use RCBS dies. How are you sizing your brass full or neck ? Are you trimming to the same length ? Do you measure case headspace.? When my case measurements from base to datum & base to case mouth are all the same . My seating measurements are exact .
 
Sometimes there as much as four thoulsant plus or minus off.
Click to expand...

The ogive is the curved portion of the bullet. You might think of it as the shoulder, or where the bullet begins to taper.

Consider this, ASSUME your die seating stem is contacting every bullet at the same spot on the ogive, might the "up to .004" variation in OVERALL LOADED LENGTH be due to differences in individual bullet length, from the point where the seating stem touches to the tip of the bullet.

very minor differences in the length of bullets (even in the same box) are not terribly uncommon.
 
What shootist is saying is that the seating stem may first be contacting the bullet tip before solid contact is made with the ogive, in which case a cure might be to drill the center of the seating stem deeper to prevent contact with the bullet tip. But regardless, differences in seating depth can occur even with consistent ogive contact.
 
First,
I will ask the obvious question that the OP doesn't clearly state. How are you measuring length? Are you measuring cartridge base to tip? Or are you measuring Cartridge base to Ogive?

Because if it is cartridge base to tip, tips may vary by as much as 10 thousandths or more.

Second, how are you measuring cartridge base to Ogive if that is what you are measuring? Because measurement error is possible.

Third, are you consistently pulling the ram the same every time?

During brass prep, are the necks consistent? Same brass? Trim length?

I ask because I always, always, always assume operator error first... And I don't know if you have checked any of this because you never said so
 
>The the die grab the bullet at the ogive or the tip of the bullet.Sometimes there as much as four thoulsant plus or minus off

Wow, if only you knew how well you are doing. Measure your bullets before you load them. Measure factory rounds. Doing pretty well, aren't you.
Don't believe internet ninja reloaders who can hold +/- 0.0001" COL for thousands of rounds.
It just doesn't matter.
The only way you could do better is if you measured EVERY bullet from some datum on the ogive to the bullet base and then calculated exactly what COL from that datum to the case head will give you the SAME seating depth and then you seated EVERY bullet in incremental steps until you reached your target. And, when you are done, you'll find the rounds are no more accurate.
Again, if only reloading manuals spent time on COL and less on selling new and useless toys.
PS: if the seating stem is gripping the bullet at all, that is NOT the appropriate seating stem for THAT bullet. Plus, a good seating stem NEVER touches the bullet meplat (nose).
 
Bullet source can be an issue. If you load bullets from internet sites who sell pull down components, measuring bullets is more important. O-give to bullet base is the pertenant measurement.
Why?
I have found up to 0.028" variations in the distance from O-give to bullet base in factory seconds & pull down component bullets. If seating comsistantly from the O-give a 0.028" variation in case capacity happens.
Is that important?
In a 308 tha's a difference on .5g of powder or the difference between a non compressed or compressed load. This impacts burn time, pressure build & IV. All of those play into barrel harmonics and impact accuracy.
Are we chasing minucia detail?
Yes! But many enjoy the challange of finding the most accurate loading for their rifle. Everything matters.
 
I've found although the difference in bullet ogive position in the same box might play a role, most often it's one of 4 things:

1) The finished cartridge is not exactly in the same linear position when you measure with a comparator and caliper; hold the round in position and open and close the caliper two or three times to get a repeatable measurement. Be sure you "zero" the caliper before you start.

2) A primer may not be seated as deeply and your measurement is longer than expected

3) When you seat the bullet, you can "feel" a slight resistance compared to previous rounds seated. The neck of the case may be slightly thicker than others.

4) You're loading a lot at one sitting and getting somewhat fatigued; you may not exert the same pressure on the press handle when you seat the bullet.

I find #1 and #3 to be most when I'm reloading. My .270, using Hornady 150gr spire, will measure 2.819" to have the ogive 0.02" from the rifling. If I'm lucky, out of 100, 50 will be right on the money. They may range from 2.817 to 2.821. I'd prefer if they're over 2.819 rather than under because I can tweak them to 2.819 by deeper seating rather than hammering them out a bit with an impact bullet puller., then reseating carefully. In any event, I'm not convinced it's necessary to worry about that +/- 0.002" unless you're in competition and need consistent sub-MOA groups. If my load usually groups at 0.723" at 100 yards, I may see a flyer or two because the seat wasn't 2.819".
Or it may be because the wind changed a bit, or I breathed wrong, or didn't use the same pressure on the trigger, or didn't have the rifle in exactly the same position as the last shot, or the powder charge was off by 0.2gr or.........what else?
 
It just happens to be coincidence that I discovered an article I planned to read someday among the many things packrats like me save, but forget about. It is a 5-part series from Precision Shooting magazine, published from October, 1993 to February, 1994, entitled, "Testing Rifles and Ammunition, by Creighton Audette. As an overview, he discusses at great length and mathematical detail the various factors that influence our INability to consistently achieve the accuracy pursued by all of us handloaders and
manufacturers of components and finished cartridges. He addresses variables like rifle manufacture, barrel vibration, the influence of cases, primers and powder and how these factors explain that any exciting group we've shot is more likely simply chance than skill. Among the excellent information presented was an example of a report about which a great deal of excitement and attention was focused wherein a 5-shot, 1000 yard group measured 4-1/4" but this should have been accompanied by an appreciation that "this same rifle-ammunition combination, in the same session of shooting,produced two groups fired under the same conditions, one of which measured 24", while the other measured 27." He considered the good group nothing more than "a very long-odds result of sheer chance."

As I finished reading the articles, I reflected on how I probably had been wasting my time and money over the last 40 years, trying to achieve what he just described as impossible. But then I recalled those instances of small groups, even though created by sheer chance, accompanied by excitement and pride of accomplishment, that kept me on track in this hobby. In the end, I recognized my flyers have not necessarily been my fault.

I'm not sure an interested reader can find this on the internet but it would be well worth the effort to try. "Google it."
 
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