Excessive seating forces

[Lucky6547]

Hello,
I encountered something new for me today...the amount of force it took to seat the bullet was such that the seater left a compressed ring on the bullet.
Have any of you encountered this before? Any ideas on the cause?
Here's more info:
New, unfired Lapua blue box 223 brass. I full length sized them all to get the necks round and consistent (some of the necks were out of round, probably from shipping). RCBS small base full length sizing die.
Sized necks OD were .2475". With a seated bullet, all the neck OD's were .250".
Sierra 69gr hpbt matchkings. Wilson micrometer seating die. Not all of the necks required excessive seating forces; in the back row you can see some were normal and not deformed. About 1 in 6 took what I considered normal seating forces, the other 5 would take so much force, a ring was pressed into the nose of the bullet.
Do the 69gr Sierra bullets need the VLD seating stem? How could necks of the same OD need different seating forces?
Thanks,
Ken

 

[fdshuster]

Ken: When you said a "ring" you were not exaggerating. What was the condition of the inside of the case mouth before you seated the bullets? Had the inside of the mouths been de-burred with at least the standard case mouth de-burring tool, looks like a rocket ship?

I use the K&M inside taper neck reamer on all my cases for a smooth effortless initial seating force, but with the 69 SMK's that have a boatail, they should seat smoothly with just the use of the de-burring tool. The ogive of the #1380's are anything but "VLD", having a much more rounded shape. Not like the 80 gr. SMK's. It would not hurt to take apart the Forster (that's all I use) and check the contact surfaces between the seater stem and a sample bullet.

Did you have a lot of resistance, then it suddenly broke free and the bullet seated? Can you see traces of copper jacket on the edge of the case mouths?

I question why you think it's necessary to use a small base die to size new, unfired brass. I also use Lapua 223 brass, do nothing more than run an expander into the case mouths to remove the shipping out of round damage, break the sharp edges of the case mouths, seat the primers, fill with powder, seat the bullet & go shooting.

I do not believe you are oversizing the case necks. .2475" before seating and .250" after are the exact same dimensions I have on my brass. Two and a half thousandths tension is about where it should be for a bolt-action.

Not an uncommon problem, but most likely a simple fix. let us know what you find.

 

[Alex Wheeler]

I use graphite on new necks to help seat the bullet. When they are new, they are sticky.

 

[RHux]

+1 on Graphite , I dip my bullet bases in a mix of #12 shot and it. Seating force on new brass is much more even.

 

[jlow]

I think the reason you are having this problem is because new Lapua brass out of the box has excessive neck tension – this is well known. This is the reason why fdshuster first run an expander into the case.

To give you some hard numbers. I use the same Lapua cases in my last run and my average neck external diameter (18 cases) was 0.2482” with this and an average neck thickness of 0.013”, I am getting an internal diameter of 0.22” and a neck tension of around 0.0018”.

So imagine you are using brass with an external diameter of 0.2475” and assuming the same neck thickness, your neck internal diameter will be 0.014” and this will give you a neck tension of 0.0026”.

Given that unfired brass has no carbon inside the neck to lubricate things, this will result in hard seating and damaged bullets.

 

[amlevin]

On new Lapua brass all I'd do to it is to run an expander mandrel through the necks and then load and shoot.

The mandrel will give you round necks and more uniform neck tension for that first firing. I've never had any issues with Lapua brass, .308 or .223, not chambering easily. Just the necks being irregular so no real need to full length size.

Once fired then my Lapua brass gets the full treatment of neck turn, primer pocket uniforming (yes, some pockets are shallower than others even on Lapua) and trimming.

 

[Lucky6547]

Thanks for the replies,
Yes, I did use the standard deburring tool on every case.
Small base used because this is for an AR-15, and I don't have an expander only die, nor do I have a neck sizing die, so I used what I had on hand.
No dry lube. No sudden break free, always an effort to seat the bullets that get the ring. No jacket material shaved off.
I may order some dry lube, but since I'm not going to turn necks for an AR, especially when every loaded case I've measured has the same .250" diameter neck, I probably won't get an expander die.
Would you guys shoot the bullets with rings? Or would you be worried about higher than normal pressures?
Thanks,
Ken

 

[fdshuster]

To keep from pulling them, I'd consider them as plinking & short range ammo only. First round foulers?

Just out of curiosity, fire 5 at 100 yards, for group, to see what they will do. Then fire 5 of the undamaged under the same conditions and compare.

Although I do not use my Lapua brass in the AR, (Winchester and Lake City only), bolt guns only, I would not run them through a sizing die before loading. They are already undersized as they come from the factory, to guarantee chambering in any rifle. You could lower the expander threaded rod in the sizing die body, so you would be taking out the shipping dents, without any sizing resulting.

 

[jlow]

Yea, the Lapua brass is indeed undersize from the factory and even after firing, you don't need a small base die. It's overkill and you get a sloppy round in your chamber.

 

[gotcha]

Just an after thought. Have you checked bullet diameters for consistency? Have you chkd. run-out on ammo with large dent VS. ammo w/o dent? ................ WOW that's a deep dent

 

[jlow]

Would you guys shoot the bullets with rings? Or would you be worried about higher than normal pressures?
Thanks,
Ken

Depends on how much pressure you put on the bullets. Denting the ogive of the bullet usually is not a problem except for affecting its BC i.e. flight characteristics. Since the ogive does not contact the rifling, changes to the ogive does not affect pressure. Your only potential concern is high pressure seating may swash the bullet lengthening the bearing surface or the diameter of the bullet which will affect pressure. Impossible for someone to tell you if that happened just looking at that photo. You could pull a couple and check bearing surface length and diameter if you have the tools. If not, take the safe route.

 

[Lucky6547]

Update:
Just got some of the imperial dry lube...it did make seating slightly easier, but some rounds still got the "ring", though it was less pronounced than before...
So the only option now is to get an expander die and mandrel?
Thanks,
Ken

 

[BoydAllen]

Did the ringed ones just fall out of the seater, or did they have to be pried out by their rims. If the latter, look into the ID of the neck portion of the seater's chamber.

 

[XTR]

Hello,
I encountered something new for me today...the amount of force it took to seat the bullet was such that the seater left a compressed ring on the bullet.
Have any of you encountered this before? Any ideas on the cause?
Here's more info:
New, unfired Lapua blue box 223 brass. I full length sized them all to get the necks round and consistent (some of the necks were out of round, probably from shipping). RCBS small base full length sizing die.
Sized necks OD were .2475". With a seated bullet, all the neck OD's were .250".
Sierra 69gr hpbt matchkings. Wilson micrometer seating die. Not all of the necks required excessive seating forces; in the back row you can see some were normal and not deformed. About 1 in 6 took what I considered normal seating forces, the other 5 would take so much force, a ring was pressed into the nose of the bullet.
Do the 69gr Sierra bullets need the VLD seating stem? How could necks of the same OD need different seating forces?
Thanks,
Ken

New Lapua brass needs to be either run over a mandrel or an expander button or the neck tension is off the chart

 

[Lucky6547]

The ringed ones do get suctioned on to the seater stem, and when I pull up on the seater stem, they fall right out.
I'll order an expander die.
Thanks,
Ken

 

[Patch700]

Although I consider Lapua brass to be the finest I personally have used , I still find that upon inspection you're going to find either out of round or dented necks... Whether or not this happens during their voyage from the factory from riding around loose in the box or wherever it still happens , this is why it's important to expand and then re-size even if you've no plans to turn necks or what have you.

If the necks can be out of round via shipping then who knows what the neck tensions could be even if they appear to be concentric to the naked eye... Wouldn't hurt to give the inside portion of the seater stem a polishing , sometimes it's enough to cause a ring where you normally wouldn't see one with lighter neck tensions.

I didn't see in your post whether or not you were using a bushing die or perhaps a std FL sizing die with an expander ( the latter of which would work just as well to bring them back around) essentially meaning if you had out of round necks and used a bushing die with no expander then they may very well be still out of round.

 

[rain164845]

It sounds like you have your seated die set to crimp too early. Screw the entire die out about 2 turns then use the seating stem to adjust seating depth back down.

 

[BoydAllen]

He is using a Wilson seating die, that is designed to be used with an arbor press. They do not have a crimping feature.

 

[rain164845]

Is there perhaps insufficient neck clearance machined into the die?

He is using a Wilson seating die, that is designed to be used with an arbor press. They do not have a crimping feature.