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Help diagnose my inconsistent seating pressure issue

I seem to be having trouble with inconsistent seating pressure which is resulting in an ES of seating depth of 0.003 (avg. of 0.0015 variance in seating depth). I am using neck turned Lapua brass (variance of 0.0004 neck thickness) which is on its 9th firing. The brass is annealed after each firing w/ a Bench Source annealer. The brass is cleaned with stainless steel media and the mouths are chamfered. Note: I have the same issue if I leave the necks with carbon inside.

For some reason, I still am getting inconsistent seating effort seating SMKs into the brass. When I use brand new Lapua brass, the seating effort is spot on each time and my ES of seating depth is at most 0.0005.

What could be the cause? Is my annealing not effective? The variance in the neck thickness too much? My neck tension too much (0.0025)?

This issue is driving me crazy.
 
jonbearman said:
Are you absolutely sure you are getting .0025 neck tension?

I believe so. Using a caliper, it is 0.3315 prior to seating and 0.334 after seating. Now, on a few of the cases, the brass thickness is slightly less (within the 0.0004 thickness variance), so the caliper shows a seated round of 0.3335. However, on some of the rounds with slightly thinner necks, the seating effort is actually greater.
 
You would be a lot better off to use a micrometer for your neck measurements. A VLD chamfering tool will ease bullet seating if you're not already using one.
If you're compressing your powder charge that could cause the problem. Not getting a good anneal could also cause problems. It is very hard to analyze over the net. Try lifting the handle slightly, give your cartridge a 1/2 turn, then down again holding your press handle down for at least 5 seconds at the bottom of your stroke when you seat your bullet the second time. It might help, worth a try.
 
I use a mitutoyo caliper for the outside diameter that measures to the nearest 0.0005 and a mitutoyo micrometer for neck turning that measures to the nearest 0.0001.

I'm already getting a slight red glow at the case neck when annealing in a pitch black room, so I am hesitant to increase the annealing dwell time.

My neck turning cutter (21st century carbide) does not seem to be holding to the same tight tolerances (it's now 0.0004) it once did. Perhaps that could be the problem.
 
I see it all the time, fellows who seem to think that a digital micrometer is somehow a substitute for a micrometer, because it has that 0 or 5 in the fourth place. It isn't, and for me it actually gives less information, because of the rounding involved, than a dial caliper. Also, I generally turn necks so that they are well inside of +- .0001. With any of my turners, using the correct expander, and even with one that is a bit oversized, with decent technique, my actual ES is more like .00015 at the extreme, usually better. When seating bullets, with a Wilson seater, if I feel variance in seating force, I group the rounds, and shoot like with like. Have you tried a dry lube in the necks, something like Imperial sells? How much neck tension do you need for consistent accuracy? On your turner, have you checked all the screws for tightness lately? I have a lot of turners, and as long as the mandrel does not pick up brass under the cutter, they will all hold good tolerance. This is not to say that there are not important differences, but they are mostly about convenience, and how smooth the cut is. The biggies are a carbide mandrel and the cutter design.
 
BoydAllen said:
I see it all the time, fellows who seem to think that a digital micrometer is somehow a substitute for a micrometer, because it has that 0 or 5 in the fourth place. It isn't, and for me it actually gives less information, because of the rounding involved, than a dial caliper. Also, I generally turn necks so that they are well inside of +- .0001. With any of my turners, using the correct expander, and even with one that is a bit oversized, with decent technique, my actual ES is more like .00015 at the extreme, usually better. When seating bullets, with a Wilson seater, if I feel variance in seating force, I group the rounds, and shoot like with like. Have you tried a dry lube in the necks, something like Imperial sells? How much neck tension do you need for consistent accuracy? On your turner, have you checked all the screws for tightness lately? I have a lot of turners, and as long as the mandrel does not pick up brass under the cutter, they will all hold good tolerance. This is not to say that there are not important differences, but they are mostly about convenience, and how smooth the cut is. The biggies are a carbide mandrel and the cutter design.

I use a 21st century cutter. I am finding lately that for some reason, with already fired brass, or brass that has already been neck turned once, the case has a bit of play on the turning arbor after using the accompanying expander mandrel. Also, I have noticed that when turning the adjustment knob, it seems to have a bit of play before it engages the cutter. In other words, it doesn't move the cutter right away. I always loosen the screw before adjusting and then tighten it again after setting the adjustment knob.

What neck turner do you use or find that has the highest tolerances?
 
I came on here again to suggest trying a dry lube in your case necks but I see that has already been suggested. Anyway it's worth a try. You might experiment with a little bit less neck tension also.
 
Forget all that nonsense. What's the target telling you about your load and the barrel's vibration. Are they in cinch? Have you fine tuned with seating depth and adjusted neck tension with a full length bushing die using a variety of bushing for that purpose? Are you using custom hand-made bullets or those that are feed out of multiple manufacturer's machines and routed into a box? If seating a bullet requires more pressure in one case than another, are you segregating the rounds so that those that are alike can be shot for different purposes [fouling, gross sighting in, competition, etc;]. Rounds are not going to be flawlessly identical all the time. Segregate. :)
 
Expanders are sized to give the desired fit with new brass that has more spring back than your annealed necks have. Also, thinner necks have less spring back. The fit issue comes from that, not a manufacturer's mistake. Here are a couple of technique tips. When you are using the turner, if it is not part of the lathe that they sell, hold both it and the cordless driver that is powering the case loosely enough so that the cutter's pressure on the neck, determines the alignment of the assembly. Don't force things straight. Secondly, when you are making the cut, advance the cutter to the shoulder rapidly, making a cut that leaves a lot to remove on the return trip, which should be slow. This will keep the neck pinned to the mandrel by the pressure of the cutter, making the fit to the mandrel much less important. When you have gone both ways, in and out, do not go back. After that, before you remove the case from the driver, you can use some 0000 steel wool on the necks, and chamfer the case mouth, carefully. The power will make the cut very fast, so don't over do it.
Added later: The slack in the adjuster should not cause a variance in neck thickness as long as the cutter is properly locked after it is adjusted.
 
hkfan45 said:
I seem to be having trouble with inconsistent seating pressure which is resulting in an ES of seating depth of 0.003 (avg. of 0.0015 variance in seating depth). I am using neck turned Lapua brass (variance of 0.0004 neck thickness) which is on its 9th firing. The brass is annealed after each firing w/ a Bench Source annealer. The brass is cleaned with stainless steel media and the mouths are chamfered. Note: I have the same issue if I leave the necks with carbon inside.

For some reason, I still am getting inconsistent seating effort seating SMKs into the brass. When I use brand new Lapua brass, the seating effort is spot on each time and my ES of seating depth is at most 0.0005.

What could be the cause? Is my annealing not effective? The variance in the neck thickness too much? My neck tension too much (0.0025)?

This issue is driving me crazy.

I'm having the same issue with my 308 handloads. Given that you also use SS pins I'm starting to think that it may be an unintended result of SS pin tumbling, however it is only an hypothesis, I have no facts to back that up. I have resolved the problem by applying the thinnest coat possible of petroleum jelly ( I use it instead of sizing wax) around the bullet base. I use my thumb and index finger to apply it. The bullets seat smoothly and easily. I am also getting more concentric rounds. However, I have the sneaking suspicion that if handled roughly (from a magazine) they may also get knocked out of alignment more easily. YMMV.
 

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The other thing to watch out for using petroleum jelly is potential contamination of your powder causing inconsistent ignition/burning which is something you are trying to do with consistent neck tension.
 
jlow said:
The other thing to watch out for using petroleum jelly is potential contamination of your powder causing inconsistent ignition/burning which is something you are trying to do with consistent neck tension.

Your opinion is appreciated and respected. I am keenly aware of that, and I am very careful to only apply it to the surface that will be touching the case neck, not the bottom or the boat tail. The very limited comparison I have made shows a very slight difference on the 100 yard target way too early to decide one way or the other, the PJ could have deleterious effects on the barrel fowling, etc... So I proceed with caution and reservations.

Regards,

Joe
 
swampshooter said:
Joe, have you tried a little graphite inside your case neck?

No, I haven't. But I might at some point. The reason is that, I believe that if I put some kind of dry lube on the neck I have to do it before I drop the powder. It seems to me that most if not all is going to end in the bottom of the case when I drop the powder in. I don't know that for sure, just a guess.

Thanks for asking,

Joe
 
I don't think that just dropping powder would remove enough to be significant, but you'll have to try it. I've done it successfully in the past when bullets were hard to seat in hunting cartridges.
I would suggest to put some #8 or smaller shot in a small jar and add graphite. Dip your cartridge neck into the shot and wipe excess off the outside of the case neck.
 
Joe your guess is wrong, I've used Graphite in my necks for years. If you want consistent seating depth you should try it.

Joe Salt
 
Joe R said:
swampshooter said:
Joe, have you tried a little graphite inside your case neck?

No, I haven't. But I might at some point. The reason is that, I believe that if I put some kind of dry lube on the neck I have to do it before I drop the powder. It seems to me that most if not all is going to end in the bottom of the case when I drop the powder in. I don't know that for sure, just a guess.

Thanks for asking,

Joe
You might try dipping the base of the bullet in the dry lube and then seat the bullet if you are worried about the powder removing some of the dry lube from the neck. I have done it both ways but I usually use the dip the neck method.
 
OK guys I believe I've found the source of the inconsistent seating pressure as well as the solution. I used to
1. Deprime
2. Clean brass with SS pins (1 hour)
3. Anneal
etc...

My hypothesis was: does the annealing raise the grain of brass much like water raises the grain of wood? The answer is don't know, but it if does what would I do about it? The answer is polish it smooth again so that there is normal seating pressure. How do I polish brass? Very simple, with SS pins. So by reversing the order
1. Deprime
2. Anneal
3. Clean and polish the brass with SS pins (1 hour)
etc...

It works. I did it today. The ss pins polish the brass and even remove the neck annealing color. The brass comes out new as if you just opened the package and the bullets seat smooth as silk. No PJ needed.

Kindest regards,

Joe
 
Joe R said:
OK guys I believe I've found the source of the inconsistent seating pressure as well as the solution. I used to
1. Deprime
2. Clean brass with SS pins (1 hour)
3. Anneal
etc...

My hypothesis was: does the annealing raise the grain of brass much like water raises the grain of wood? The answer is don't know, but if does what would I do about it? The answer is polish it smooth again so that there is normal seating pressure. How do I polish brass? Very simple, with SS pins. So by reversing the order
1. Deprime
2. Anneal
3. Clean and polish the brass with SS pins (1 hour)
etc...

It works. I did it today. The ss pins polish the brass and even remove the neck annealing color. The brass comes out new as if you just opened the package and the bullets seat smooth as silk. No PJ needed.

Kindest regards,

Joe
How does annealing have any effect on the smoothness of the inside of the case neck? As long as you are polishing before sizing, what difference does it make if you polish before annealing?
 

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