Inconsistency with seating depths

[AndrewS]

I am struggling!! I have a Redding Big Boss II, RCBS case holder and Whidden Gunworks micrometer die. I am reloading Noser cases, 6.5 CM with Berger Hybrid 140g. I am measuring with electronic caliper and Hornady comparator. My depths are all over the place. For example, I set my die this am. Started seating. First 4 were 2.120 (to ogive), 2.117, 2.105 and 2.136. Now this is a pretty precise die. I use a plain Jane RCBS for my 300 WM and it is way more consistent. Any suggestions on what is going on? Why am I getting such all over readings? It took me an hour to stuff 20 this morning

 

[AndrewS]

I just opened my digital caliper all the way and closed it about 10 times. Goes to zero every time. Also just double checked my finished loads with dial calipers and the measurements are still the same.

 

[KYpatriot]

Several things. First, inconsistencies in ogive construction. Your calipers and your die are likely using two different points on the bullet to measure from.

First rule out your measuring device. Does it it consistently read the same thing each time on a the same round?

Next look at the press and caseholder. Is it clean and linkages lubed? Are you using the same cam over pressure on the handle each time? Using a different "technique" on the press handle can account for a few thousandths, maybe not fifteen thousandths like your are seeing but tolerances can accumulate.

How consistent is your neck tension, and is this a compressed load?

Finally, look at the bullets on the finished rounds you had trouble with...are you seeing a bright ring where the seating stem cone in the die contacts the bullet? If so, the micro, perhaps not even visible tool marks left from the machining of the die stem can act like a fingerprint and give the stem the ability to hold onto the bullet, causing the bullet to move some on the upstroke. If it is severe enough sometimes you can even hear a little popping sound as the stem "lets go" of the bullet, or you may feel this through the press. To fix this take the die apart, get some 000 or 0000 steel wool, sacrifice a .22cal bore brush by chucking it in a drill and as you spin it let it pick up some of the steel wool. Form it into a cone shape, and polish the inside of the seating stem. Slicking up the seating stem will improve this problem more than anything.

Even so, if you want seating depths that are within .001 across all the rounds you will have to intentionally set the micrometer die to a setting you know will be a few thousandths long, seat a round, measure it with the comparator, then adjust the die the number of thousandths that specific round requires to get the exact depth you want. Reset your die to the long setting, and repeat this process for each round.

 

[AndrewS]

Several things. First, inconsistencies in ogive construction. Your calipers and your die are likely using two different points on the bullet to measure from.

First rule out your measuring device. Does it it consistently read the same thing each time on a the same round?

Next look at the press and caseholder. Is it clean and linkages lubed? Are you using the same cam over pressure on the handle each time? Using a different "technique" on the press handle can account for a few thousandths, maybe not fifteen thousandths like your are seeing but tolerances can accumulate.

How consistent is your neck tension, and is this a compressed load?

Finally, look at the bullets on the finished rounds you had trouble with...are you seeing a bright ring where the seating stem cone in the die contacts the bullet? If so, the micro, perhaps not even visible tool marks left from the machining of the die stem can act like a fingerprint and give the stem the ability to hold onto the bullet, causing the bullet to move some on the upstroke. If it is severe enough sometimes you can even hear a little popping sound as the stem "lets go" of the bullet, or you may feel this through the press. To fix this take the die apart, get some 000 or 0000 steel wool, sacrifice a .22cal bore brush by chucking it in a drill and as you spin it let it pick up some of the steel wool. Form it into a cone shape, and polish the inside of the seating stem. Slicking up the seating stem will improve this problem more than anything.

Even so, if you want seating depths that are within .001 across all the rounds you will have to intentionally set the micrometer die to a setting you know will be a few thousandths long, seat a round, measure it with the comparator, then adjust the die the number of thousandths that specific round requires to get the exact depth you want. Reset your die to the long setting, and repeat this process for each round.

Measuring device double checked and a different one used to confirm same finished length.

These are new, unfired cases. Of the last 40 I did, maybe 5 or so were a little stiffer going in, so neck tension different on a small amount. Pull pressure is consistent. Not a compressed load.

I think this "fingerprint" or sticking may be the problem. I will send a pic.

Thanks for such detailed response, KYpatriot!

 

[AndrewS]

So I am getting this ring on half the bullets or so.


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[AndrewS]

Close up


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[dauntedfuture]

Possibility: You have too much neck tension and what's happening is that as you seat the bullets you are deforming them. The ring is from the seater in the die. Some bullets are getting deformed more than others and its resulting in inconsistent seating depths. Your bullets are .264, what's the inside diameter of your cases? Is should be consistent and should be .262-.263. If your ID is smaller then .262, you need to look at a different sizing die or a larger bushing or turn the necks. If you are running a bushing die without the expander ball and you are not turning the necks you will need to in order to get a consistent ID and neck tension. Lots and lots of problems with seating bullets are from sizing issues. You might not see this with bullets with thicker jackets.

 

[AndrewS]

Possibility: You have too much neck tension and what's happening is that as you seat the bullets you are deforming them. The ring is from the seater in the die. Some bullets are getting deformed more than others and its resulting in inconsistent seating depths. Your bullets are .264, what's the inside diameter of your cases? Is should be consistent and should be .262-.263. If your ID is smaller then .262, you need to look at a different sizing die or a larger bushing or turn the necks. If you are running a bushing die without the expander ball and you are not turning the necks you will need to in order to get a consistent ID and neck tension. Lots and lots of problems with seating bullets are from sizing issues. You might not see this with bullets with thicker jackets.

Everything I'm loading right now is unfired Nosler brass. ID is .260-.261. My fired cases are .263. So should I size the unfired brass first? As for thicker jacket bullets, what fit that? I have some 139g Scenars on the way.


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[distantfoe]

I didn't realize nosler made 6.5cm brass. If you're forming them out of some smaller caliber brass then you're running into a doughnut. When necking up, the thicker shoulder material will be brought up into the neck causing a doughnut at the base of the neck.

 

[918v]

Case tension variance will induce OAL variance.

Bullet ogjive variance will induce OAL variance.

Sort your bullets by length. Use minimal case tension.

 

[Deadshot2]

So I am getting this ring on half the bullets or so. View attachment 48913


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This is probably the main cause of your problem. Have you annealed the cases? How about the chamfer of he case mouth?

If the case mouth ID's aren't exact, and the case metal at the same state of work hardening, varying seating pressures will result in different seating depths. The ring tells me that you have some really heavy neck tension.

To prevent this I do several things. I anneal cases frequently, often as much as every firing. After sizing I use a Sinclair mandrel expanding die to make sure that all my case neck ID's are uniform regardless of my sizing method. I use an RCBS 3-way tool for trimming so I have totally uniform chamfer's on my case mouths.


Lastly I take any press flex out of the equation by making my seating dies into Dead Length Seating Dies. This is as simple as finding a washer that will just fit the case while in the shell holder. Put the washer over the case, raise the ram, and adjust the die so you get a firm cam-over. The washer keeps the die from crimping the case but there is absolutely NO variation in how far the case is pushed into the die-------- period, no matter how sloppy the press may be. Once you adjust the seating depth each and every bullet will be seated to the same depth provided the neck tension isn't so high you push a groove into the jacket.

If you like high neck tensions you can minimize the tendency of seating plugs to form these rings by adding some devcon or J-B weld to it. Clean and de-grease the inside of the seating plug and apply a thin layer of he epoxy to the inside. Then seat a bullet that has been waxed up real well with Kiwi Shoe Polish. Seat the bullet and secure the press handle with a bungee cord or hang a weight on it. Let the epoxy cure and then part the bullet from the plug. Drill a small relief hole in the epoxy where the bullet tip sits. You now have a plug that will seat bullets with no rings. It may have a tendency to stick a little at first when you are lowering the ram but it goes away. Some guys will go to the extreme of chucking the plug in a lathe, putting the epoxy in place, then the bullet. They will then "dial in" the bullet by indicating off the bearing surface of the bullet and "tapping" it into a position that yields the lowest TIR. They even make seating plugs like this for each bullet they use so it fits the ogive perfectly.

 

[KYpatriot]

Andrew before getting too crazy, try polishing the inside of the seater stem as I described. This will cure 90% of your problem.

 

[AndrewS]

Andrew before getting too crazy, try polishing the inside of the seater stem as I described. This will cure 90% of your problem.

Wow, that was it! Just put 3 through it after the steel wool and all the same! Thank you all so much for your help!


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[Sig Marine]

Several things. First, inconsistencies in ogive construction. Your calipers and your die are likely using two different points on the bullet to measure from.

Even so, if you want seating depths that are within .001 across all the rounds you will have to intentionally set the micrometer die to a setting you know will be a few thousandths long, seat a round, measure it with the comparator, then adjust the die the number of thousandths that specific round requires to get the exact depth you want. Reset your die to the long setting, and repeat this process for each round.

Seating stems in seating dies do not contact the ogive of the the bullet, as the ring mark on your bullet from your seating stem indicates. Because of this, any variation in the bullet shape will cause small differences in the base to ogive measurement. Redding sells a gauge called an "Instant Indicator Headspace and Bullet Comparator" that measures accurately from the ogive and best used on a turret press. Below are links to the gauge and a video on how to set it up. Basically, you do what KYpatriot says in his post, you seat short, measure, adjust your seating die the proper amount and check/verify the round. A little more time consuming but it's a much more accurate way to seat.

Redding Gauge: Instant Indicator Headspace and Bullet Comparator | Redding Reloading Equipment: reloading equipment for rifles, handguns, pistols, revolvers and SAECO bullet casting equipment

Video: https://www.youtube.com/watch?v=ZAgAnIIxqHA

Hope this helps...Sig Marine

 

[AndrewS]

Seating stems in seating dies do not contact the ogive of the the bullet, as the ring mark on your bullet from your seating stem indicates. Because of this, any variation in the bullet shape will cause small differences in the base to ogive measurement. Redding sells a gauge called an "Instant Indicator Headspace and Bullet Comparator" that measures accurately from the ogive and best used on a turret press. Below are links to the gauge and a video on how to set it up. Basically, you do what KYpatriot says in his post, you seat short, measure, adjust your seating die the proper amount and check/verify the round. A little more time consuming but it's a much more accurate way to seat.

Redding Gauge: Instant Indicator Headspace and Bullet Comparator | Redding Reloading Equipment: reloading equipment for rifles, handguns, pistols, revolvers and SAECO bullet casting equipment

Video: https://www.youtube.com/watch?v=ZAgAnIIxqHA

Hope this helps...Sig Marine

Thanks for sharing Sig! That comparator looks slick! Yeah I know I'll have different readings from one to the next, they were just WAY off.


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