Bullet Seating

[akinswi]

Im ready to load another batch of 30-06.

I typically sort my Match bullets by ogive. But was wondering if it would be more efficient to first seat the bullet with my competition seating die, then measure then adjust the die to my specs that I wanted then seat them again.

thanks

I dont measure overall length I measure base to ogive.

[Unclenick]

Since the point of contact between the seating die and the ogive of any given bullet profile will be the same, you should then have matching ogive measurements (+ or - the usual couple of thousandths) regardless of whether the bullets have a matching base-to-ogive measurement or not. In other words, if I understand what you mean correctly, seating first will camouflage your attempt to distinguish bullets by measuring the individual bullet.

[akinswi]

Yes, If I want my Base to ogive measurement lets say 2.717 . I would zero my calibers and I would sort the bullets in lots of +- .001.

Then I would load each lot. And set my seating die to give me the depth I want

Basically what your saying is that I would still need to sort by ogive

[Shadow9mm]

Im gonna need some clarification.

What do you mean by "sort my match bullets by ogive" Are you measuring from the base of the bullet to a point on the ogive? Basically sorting the bullets themselves?

I am unclear on how this relates to seating.

For seating, yes i seat the bullet a little then measure. Then adjust the micrometer die down. Then i measures again to make sure i got it right.

I feel failing to measure over all length is a mistake. Tools can break or be lost. As there are no standards for comparitive tools, like ones that measure off points on the ogive if you lose that tool you are in trouble.

What i do, once i have finalized my load, is measure over all length on 30 of them. I average that number and record that, as well as the high and the low for my records. That way if anything ever happens to my tool, i can set it up off the over all length if i have to.

[akinswi]

Shadow,

the problem with Overall Length on Hollow Point Match Bullets in my Case, Sierra Match kings the tips are jagged and inconsistent, the ogive is more consistent baseline for measurement.

For example, The magic number for my rifle in 30-06 is 2.717 Thats the base of the case to ogive in my comparator. Now If You measure the COAL of that same round it can vary from 3.320 to 3.323, because the tips are consistent.

As long as my overall Length is under 3.340 im good. Because they are being fed from enbloc clip .

If I sort each bullet, by base to ogive (base of bullet to ogive) my ammo is 99% more consistent in terms of length remember the tip never touches the rifling and is basically there to help with BC


As far as tools go I faith that each of the calipers I use will fall with in 1 thousandths of eachother.

[44 AMP]

To be clear, you are measuring from the base to a point (which you chose) ON the ogive. The ogive is the entire curved/sloped portion of the bullet from where it first reduces from full bore size down to the tip.

This can be a very good repeatable point, but will be a different point for each different type/style of bullet and each different rifle.

Total COAL should always be checked, to be sure its under max length. No, the bullet tip doesn't touch anything in the barrel, but you need to check length to the tip just to be sure of proper feeding in repeaters.

My method is simple, just set a caliper for the max COAL, and pass the loaded round through the jaws. IF it won't fit it needs reseating. IF it goes through, you're good to go.

What point you use, and how you seat your bullets below max COAL is entirely up to you.

[jetinteriorguy]

If you sort the bullets from base to a datum point, and if that datum point is the same diameter as the lands in your barrel, and if your seating stem also makes contact on this same datum point then your ammo will all have the same distance from the datum point to the lands in your chamber. A few ‘if’s’ in there that make it tricky.

[Unclenick]

Originally Posted by akinswi

Basically what your saying is that I would still need to sort by ogive

Yes. Because the seating stem contacts the ogive, the cartridge is consistent from the case head to that contact location, regardless of how far the bullet base sticks down into the case. So you lose the bullet base location information.

I don't know that the seating die's point of contact on the ogive matches your comparator's contact point well. You can put Magic Marker on a bullet to see where the seater touches it, then place your comparator over it and see where the comparator touches it. Look at how close those contact locations are. Chances are they are close enough that you won't get a lot of variation in that distance, and you can ignore it. But suppose they have a quarter inch or more between them. In that case, you may find the distance between where the two contact the ogive varies a few thousandths among bullets that came off different tooling sets (the thing that is sorted with base-to-ogive measurements finds). In that case, you might feel better if you bought another insert that is one caliper too small and reamed it to match the seating die contact diameter. But that's a pretty tight level of detail, so while it might take a couple of thousandths out of the apparent variation in the resulting loaded rounds, I would think sorting the finished rounds by that length value is unlikely to gain you anything on paper.

[gwpercle]

In the interest of consistency ... I would use a method that allowed the bullet seating operation to be done in one step .

Seating the bullet in the case neck will give it the best tension ... going back and seating the bullet deeper might loosen the tension and also might give differing neck tensions ... thus having inconsistencies from shot to shot .

For accuracy ... seat the bullets in one step .
Gary

[Shadow9mm]

Originally Posted by gwpercle

In the interest of consistency ... I would use a method that allowed the bullet seating operation to be done in one step .

Seating the bullet in the case neck will give it the best tension ... going back and seating the bullet deeper might loosen the tension and also might give differing neck tensions ... thus having inconsistencies from shot to shot .

For accuracy ... seat the bullets in one step .
Gary

What about the match shooters that seat short, and only do the final seat right before the match to prevent the bonding of the bullet to the neck?

[44 AMP]

What about the match shooters that seat short, and only do the final seat right before the match to prevent the bonding of the bullet to the neck?

For them, I'd recommend OCD counseling...

on the other hand if it seems stupid, but it works, its not stupid...

[Nathan]

Do you see that on the target?

[akinswi]

Thanks Nick,

There is a tool that measures from the shoulder to the ogive. apparently its suppose to be more accurate.

https://bullettipping.com/products/s...th-comparator/

[Nathan]

There is a tool that measures from the shoulder to the ogive. apparently it’s suppose to be more accurate.

Before you dive into that, ask yourself what it is telling you. I think you will find it is adding the base to ogive variation to any seating variation. To get you the variation of 2 processes….sizing and seating. With double variation, which will you work on?

Then, I always go back to the datum structure. In many push feed actions, you could argue that the base is pressed into the chamber making shoulder datum to ogive a control point. In fixed ejector actions, this is not true.

I guess I’m just saying I don’t like it as I don’t think it tells me the right things. That said, I do respect how in a push feed it is a more valuable number. I wonder if sorting by this gage shows on the target with 30 shots or more??

[gwpercle]

Originally Posted by 44 AMP

For them, I'd recommend OCD counseling...

on the other hand if it seems stupid, but it works, its not stupid...

LIKE LIKE LIKE !!!
Gary

[Unclenick]

Originally Posted by akinswi

There is a tool that measures from the shoulder to the ogive. apparently its suppose to be more accurate.

https://bullettipping.com/products/s...th-comparator/

Yes. It looks very much like the one I made twenty years ago, except they are using a digital indicator.



On mine, that knurled part at the bottom unscrews. It is reamed with a chamber reamer to form a chamber shoulder. The plunger under the indicator is was first reamed to bore diameter (not groove diameter) and then also reamed with my chamber reamer to form a throat. That way it touches the bullet ogive right where the actual chamber will.

Another tool that will make that measurement is the Redding Instant Indicator, which came out about three years after I made my tool. It differs in that it uses carbide sizing die neck inserts to determine the point of contact. I like using the chamber reamer better, but my design was probably a little labor-intensive for manufacturing when I made it. Today, they'd just program a CNC tool to make the parts conform to a chamber.

Originally Posted by Nathan

Before you dive into that, ask yourself what it is telling you.

What it tells you is how far the bullet will be into the throat when the case shoulder touches the should in the chamber. It's a measurement that is only useful to cartridges that headspace on the shoulder. A primer has much higher brisance than gunpowder, so the primer fires and backs out against the breech much faster than the powder gets burning. The forward drive of the firing pin plus that rapid push-off against the breech face by the primer all serve to drive the cartridge forward against the headspace stop (in this case, the shoulder) and holds it there while the powder starts building pressure. During that time, the head of the case isn't in contact with anything and won't be until pressure stretches it back, reseating the primer. So it is the distance from the shoulder to the bullet ogive at its throat contact point that actually determines what bullet jump is, and not the ogive to head measurement. That shoulder-to-ogive distance being consistent makes bullet jump consistent. The measurement to the head can't do that.

[akinswi]

Nick, you should have gotten a patent on that. Or has the idea been around while?

[Nathan]

Thanks @Unclenick. You brought something to my attention that I had not considered.

[Unclenick]

Thanks, guys.

Yeah, I probably should have patented the design. Be easy to make on CNC machines now. I also thought of the hybrid ogive (tangent transitioning to secant ogive) about three years before Berger came out with theirs and might have been able to patent that, too. However, designing something and coming out with a production model takes time, so both Redding and Berger may already have had the ideas in development when they occurred to me and already had their patent disclosures filed. So it may not have worked out in either case. For a technology that is generally developing, it is not uncommon for different inventors to come up with the same solution nearly simultaneously. It's sort of like the evolution of an invention is driven by technological circumstances, and if one person doesn't get to the patent office with it or something close enough to it, another will. The most famous example is Elisha Gray, who, like Alexander Graham Bell, invented the telephone but got to the patent office to file his patent application just two hours after Bell did, and that cost him the patent (not to mention fame and fortune). Usually, things aren't quite that close, but months apart isn't all that unusual. I'm currently a witness in a patent dispute over one of my old patents that has come down to months of gap between who had what documentation and when.

To see the speed of primer ignition and the primer cup backing out vs. powder and pressure, take a look at this video. The most informative view starts at about 8:30. The guys doing the experiment use one of those tiny little pinfire novelty guns to fire a ball into the primer on an exposed round of 9mm. You can see the primer impacted by the pinfire ball, and it takes about 10 microseconds for it to penetrate into the primer cup completely. I don't know when in that 10 microseconds, the priming mix actually started to burn, so I have a 10-microsecond range in all timing. It appears the primer has backed out and cleared the primer pocket at 60-70 microseconds after the impact, and you can see flame and gas from the powder burning just in front of the flash hole chasing it out. The initial bullet movement is a little hard to resolve because the case moves a little and stretches a little before it lets go, but it appears to me the bullet actually starts slipping out of the case mouth at about 90-100 microseconds after the primer is struck. This agrees with data from Brownell et. al. The bullet clears the case mouth at about 490-500 microseconds. You catch a brief flash from the powder flame at its base that extinguishes as the pressure drops, lowering the burn rate, and the powder grains start to get too far apart to carry the ignition process forward.