Big Bullet Runout...Don't Know Why

[Phil3]

I am new to reloading and am puzzled as to why I have bullet runout on the order of .007". Especially with the equipment I am using.

I am loading 223 Remington, using new Winchester brass. That brass has been trimmed as necessary, the neck chamfered inside and out, the neck made round if needed (some did), but was not resized. The bullets are Sierra MK 53 grain hollow point flat based. The press is a Forster Co-Ax and the bullet seating die is a Redding micrometer type. I set the die to seat the bullets to magazine length, or 2.25". This process went without incident. I used a Sinclair concentricity tool to measure some loaded rounds. For those not familiar with the tool. the case sits on its side, on little fixed balls. The case is then rotated on those balls, while a dial indicator measures runout on part of the case, neck, or bullet. The case and neck were around .0035". But the bullet, measured near the ogive is .007". When rotating the cartridge, you can actually see the bullet wobbling! I am shocked these rounds shot 1/2" groups at 100 yards out of an AR15 on a bipod, with my daughter doing .3". But, surely, this kind of runout is not right and perhaps accuracy can be better yet. Is there something I might be doing wrong, tool setup incorrect, or...? I wish Redding would provide die instructions on-line like Forster, but they don't (that I can find).

Any guidance is very appreciated. I am new at this and want to get things right.

Phil

 

[LRPV]

If this is virgin brass I wouldn't worry too much until you sized it and loaded it again. If the problem persists then I would be worried. Check your fired cases and see how straight they are. Right or wrong, I full length size all new brass before firing it the first time. You could have some other problems but for right now I'd blame it on virgin brass.
Jason

 

[bigedp51]

There are 12 steps in drawing and forming the brass to make a .223 case (see photo below), I'm in 100% agreement with LRPV above. Full length resize your new brass and help straighten out the drawing process. Fire the cases and then check your runout after they have been formed to your chamber.



Complete Precision Case Prep (from the main page of Accurate Shooter.com)
"Step 1
Method: Use a Redding Body Die or Full-Length Sizing Die to force the shoulder and body into a standard configuration."

http://www.accurateshooter.com/featured/complete-precision-case-prep/

 

[Outrider27]

+2 on LRPV's post. And you have raised your daughter well, since she can out-shoot her old man.

 

[Shynloco]

Phil,
I also agree with MOST of what LRPV writes, except the part of FL sizing new brass BEFORE it is fireformed. The most I ever do is neck size if the mouth of the casing has been dinging during shipment. And I've not seen your issue with .223 brass before, but have with 6.5 X 55 brass made by what some believe, is the top manufacturer of brass. I too use a Sinclair Concentricity Gauge which requires you to "finger role" the brass. Personally, I'm not a huge fan of that method, BUT, I had a .008 runout on 8 -10 NEW pieces out of 50 I selected out because of it's weight similarities. I attempted to FL resize the brass BEFORE firing it and there was hardly any improvement using a Redding FL resizing die. Called Redding and they had me send in the die with three of the worst runout pieces of brass. They tested the Die and found it to be within tolerance. But when it came to the brass, they discovered all three pieces were flawed in that their bases were crooked and thus flawed during the manufacturing process. I ended up tossing all those big runout pieces even after attempting to correct the problem by fireforming. Bottom line, I quickly learned you simply cannot correct flawed brass when the base is crooked and that it does happen occasionally. SO shoot your brass and check it again. And unless every piece has that high runout error AFTER being fireformed, it isn't your die, but rather bad brass. Just my thoughts and experiences on your issue.

Alex

P.S. Just make sure your shell holder is concentric in terms of being level on the bottom. It's rare, but have heard of a few bad shellholders now and then.

 

[Phil3]

OK, went out to the garage and did some measuring. I performed four tests, 5 sample cases or loaded cartridges as needed. All Winchester brass. As an aside, I measured neck thickness variation and this was typically within .001.

LOADED CARTRIDGES RUNOUT
Note: The five measurements are using the cartridges in the same order for both neck and bullet runout.

Virgin Brass - Loaded: Neck Runout
.0045 .0040 .0035 .0020 .0040

Same Samples As Above: Bullet Runout
.0090 .0080 .0060 .0050 .0060

1X FIRED BRASS NECK RUNOUT
Note, the last three are estimates as the necks were a bit dented from hitting the ground after being ejected, but believe all to be around .001".

.0010 .0010 .0010 .0010 .0010

NEW UNFIRED BRASS NECK RUNOUT
.0020 .0030 .0015 .0030 .0020

My question is why is the bullet runout much higher than the neck runout, sometimes twice as much. I pulled the bullet from cartridge #1 (the one with .009 bullet runout). The bullet looked fine. I reseated it. Total bullet runout was now .008", a .001 improvement.

Do my measurements shed any additional light?

Phil

 

[LRPV]

Neck run out will intensify bullet run out. The farther away from the crooked part you measure, the more it will show up. Hopefully this makes sense. Move your Sinclair set up to where the indicator is closer to the nose of the bullet and you should get even higher numbers.

 

[hotrodlouie]

Remove the expander ball from your die and then check neck run out verses using expander ball in die to compare. If you go back to other post about bullet run out they give good suggestions about what to look for problems. One thing I found interesting is the seating die two different brands the bullet is .005 loose in the bore and causes the bullet to start cock it in the case.

 

[wapiti25]

Imperial Dry Neck Lube will lower the force (drag) on the expander button, which helps keep the button from bending the neck. Inspect the seating die stem, piston/seat for any defects or build up. I think your rifle chamber may be helping by straightening your ammo.

 

[bigedp51]

The number one cause of neck runout when reloading cases is caused by the expander button being locked down off center and pulls the necks off center inducing runout.

The second biggest reason for neck runout are dings and dents inside the case rim which hold the case off center in the shell holder on the down stroke of the press.

The third reason is unequal case wall thickness but this will show up after the case has been fired and has been warped. (banana shaped)

The Lee Collet die eliminates the top two problems.

Or plan "B", place a o-ring under the lock nut of the decapping/expander button and let the spindle "float".