A friend has a custom chambered 270 Win. It appears to be a slightly tight necked chamber. I took some Win virgin brass, checked lengths, sized them all full length, rechecked lengths again. Brushed out case necks, deburred, the whole 9 yards. All brass was in spec and I picked 21 cases all the same length.

I loaded them. All bullets were seated to the same length with a micrometer die and checked with an RCBS precision mic.

Out of 21, 6 would not chamber. The culprit was case mouth flaring by about .0005 to .001. I called the smith and he said it was likely that the case mouth was bottoming out in the seater die, but wouldn't it stand to reason that all the hulls should do the same given the same length?

What could it be "bottoming out" to? It's a competition seater by Redding and I've never had this happen before.

Any ideas?

I did wind up unloading these 6 rounds, ran the outside neck turn on them for about the first mm at the case mouth, trimming away .001, resized, recharged, reseated, and they all chambered just fine.

is this really a die issue?

were the bullets hard to seat or give signs of being harder to seat than the others?
I had a simular problem with 30/06 brass. it causes the neck to buldge at the neck shoulder junction,

No. The bullets seated smoothly. I had the die sent to Redding to ream it where it squeezes the neck just over a thousandth smaller than a loaded round during sizing. I don't use and expander.

Sounds as if it is going to be necessary to turn the outside of the case necks, or run a more standard sized reamer into it. Best of luck!

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The culprit was case mouth flaring by about .0005 to .001.

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What could it be "bottoming out" to?

Hey Doc,

I'm kinda confused about the term "flaring" but it is certainly possible that if a Seater Die is turned too far into the Press the results can "bugle" (flare?) the case mouth due to too much ("bottoming out") crimp.

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Originally posted by Gerry:

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The culprit was case mouth flaring by about .0005 to .001.

quote:

What could it be "bottoming out" to?

Hey Doc,

I'm kinda confused about the term "flaring" but it is certainly possible that if a Seater Die is turned too far into the Press the results can "bugle" (flare?) the case mouth due to too much ("bottoming out") crimp.

Wouldn't it do the same thing if I ran an empty case in there without seating a bullet? I tried that too and not one case had a problem chambering. It was only after seating a bullet.

50 + years ago Lyman/ideal suggested reloaders skip the crimp process, seems step sequence as in step #1, step#2, step#3 and step#4 was too much to keep up with, if done incorrectly crimping has more chances to create problems than it solves starting with reduced bullet hold (tension of the neck).



Case length is a good start but the effort is wasted if the seater die is not set up correctly.

Setting up the seater die starts with adjusting the die off the crimp portion of the die with the ram up and case installed, then with the ram up the die is adjusted down to the case where it JUST TOUCHES the mouth of the case, that's it but it must be remembered the seater die offers no case support, if crimping is not done correctly the case neck and or shoulder and or case body has no choice but to squat, flare, bulge or upset.



I made a seater tool that I can use with a can crusher, the bullet can not get out of alignment and the case has support to the shoulder, it is not a must have, it is nice to have when seating difficult to seat bullets.



"stand to reason" back the seater die off, install a case in the shell holder and raise the ram, then lower the seater die until the die contacts the case mouth STOP, then secure the die to the press with the lock ring, then another step, do not forget to back the seater plug off, adjusting the bullet seating depth is best done with a modified case/transfer but that is for another day.

F. Guffey

I was told by Dillon I should seat on one position and crimp on another, first off I am not going to start over with the dies, my old dies come with me and I do not load on a progressive with out a lock out die.

To understand the discussion, there is a conflict when seating and crimping in one operation, the bullet is moving down, the crimp is locking the case to the bullet, when this happens the case mouth has no choice but to bulge, and the crimp does not flare the mouth of the case.

F. Guffey

Hey Doc, Are you using those Expanding Solid - Politically Correct Bullets? If so, perhaps those 6 have a slightly w-i-d-e-r dimension than the others, which would not surprise me due to the way they are made.

Or perhaps the Bullet got "slightly skewed" as it was just entering the Case Mouth and resulted in Flaring it slightly along one side(Ovate).

Or perhaps the Case Mouth "thickness" was just a bit more on them.

Anyway, now you have " 6 " Rounds different than all the rest. That might not bother anyone else on the Board, but I would segregate them from my Hunting Rounds. I like everything as exactly alike as possible.

Best of luck to you.

Maybe running the cases into a Lee factory crimp die to close the case mouth flare.
You wouldn't actually have to make a full crimp it you don't want a crimp, just squeeze the flare a bit so the case mouth is in line with the rest of the neck.

Sorry I can't help with determining what is actually causing the case mouth to flare during bullet seating. This rifle's custom chamber is tight, so tight a one thousands of and inch flare prevents the cartridge from fully chambering. I'd be running very ctg through the Lee FCD just as an insurance policy.

Well, I will double check the die as it is in the press. I have had a locking ring on it secured for the Forster press for about 3 years now.

I do not crimp. Don't like to mess with it.

All bullets were checked for symmetry and all passed with the micrometer in terms of diameter and bearing surface length.

I think what I'll do is trim a batch of brass another thousandth as well and see if I run into the same problem. That will be after I adjust the die.

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Wouldn't it do the same thing if I ran an empty case in there without seating a bullet? I tried that too and not one case had a problem chambering. It was only after seating a bullet.

Hey Doc .....

Understand where your're coming from ..... let's try this one then.

Outcome was only 6 of 21 seated bullets; meaning what did we do with the other 15 that made the 6 different as apparently the bullets & cases are all the same up to this point? What's different?

Crimp or Seating Stem appear to me to be the only two variables remaining?

Could it be that you didn't "ease" the bullets into the seating stem?

If the bullet is sitting atop the case on the upstroke as it goes into the Seater Die AND it's askew AND hasn't made full contact with the Seating Stem yet (different nose shapes) it could still potentially be askew on top of the case as the stem, bullet & case align; depending on the cut of the Die (internal dimensions) you could be giving it an "uncentered" shove into the mouth of the case.

Gerry, at this point I suppose anything is possible. But with the way my cases are sized, the boat tail on the VLD sits nicely and straight as I begin to raise the ram and begin seating.

As soon as there is resistance with seating, I back out, rotate the case and seat a little deeper. I do this 3-4 times so at no point is the ram ever ran quickly or forcefully.

When I get home I'm going to back the die off about 1/2 turn, and reset the micromter/seater stem. I have his rifle still and will check it out. BTW, I think the difference in fired v. loaded case neck diameter is only about .002 in this rifle. I'll have to double check that.