Problem with Shoulder setback 223 AR

[dbarnhart]

I've beeb reloading 223 successfully for my HK. I've probably put 7K rounds of my own reloads thru it. I've just bought a new AR and am finding it somewhat more finicky. The problem seems to be related to the rim-to-shoulder dimension. I'm using the Dillon case gauge and have a one-to-one correspondence:

Rounds that pass the case gauge test feed flawlessly.

Rounds that fail the case gauge test (and are too long) jamb when fed.

Simple problem, right? My press is a Hornady LnL-AP I've used both RCBS and Dillon dies. In both cases I need to run the die down to the point where there is an interference fir. In other words:

1. Raise the ram.
2. Screw the sizing die in until it contacts the shellplate.
3. Lower the ram.
4. screw the die in a little more.

I will still occasionally get a case that fails the case gauge test even after being sized.

I should add that factory ammo (American Eagle) feeds just fine.

Any ideas?

 

[cfullgraf]

I would get an RCBS Precision Mic gauge or a Sinclair Bump gauge. These will tell you how much you are setting the should back and could tell you if your getting some variability in the amount of re-sizing.

There could be some flex occurring in your Hornady and varying depending on what your are doing at the moment (all stations full at time, and not full at times.).

Re-size on a single stage press and get that variable out of the equation.

 

[A Pause for the Coz]

I have spent a whole lot of time pulling my hair out with the same issue you have.
It was not until I purchased a case gauge that I realized. It has nothing to do with the sizer your using. ( I think) I have not used a small base die.
I have used the LEE sizer and a Lyman sizer.

Even after sizing in both sizers I still get cases that wont gauge.
It might be machine gun rounds and the base may have taken a pounding.

My solution was simple.
Any case that does not gauge gets tossed.

Since I implemented that policy I have not had a single jam in my AR.
Used to get 2 or 3 a outing.

 

[918v]

Are you crimping?

 

[dbarnhart]

>>>Are you crimping?<<<

no

 

[blarby]

I would get an RCBS Precision Mic gauge

Which will help weed out the ones that shouldn't be shot, and its a great tool !

I think what you are seeing is something I started seeing when loading bulk .308... its almost like "case wiggle"

Something I did ( with the aid of a precision mic ) was measure each case going into the dies, and each case coming out.

Found somethin.....

Either the thickness of the rims on the cases was different by a thou- or my dies were moving.

Guess which one it was ?

Neither..well, sorta neither......

It was the shellholder.

Some shellholders allow a lot more play than others.

My RCBS .308 shellholder rejected about half my rims. They wouldn't go in, at all. This proved to be a great asset, as these were the cases I was having problems with in my match chamber. Some rims had high and low points...some were perfectly flat. Only the flat ones got past that RCBS shellholder.

My lee and lyman ? Let 'em in just fine.

Now that I size using only the RCBS shellholders- no jams.....

Your AR may simply have a very tight chamber that notices that 1 or 2 thousandths of play you use to be able to get away with on your HK.

A die, set properly, with a shellholder that holds the shell properly, should not vary in the length of sized brass from shoulder to rim....... unless your dies are moving.

Given that, I'd say :

Either your dies are moving

or

Your rims are warped...and a shellholder that allows enough slop to interfere with function in your AR is being used to size your brass. Could also be your shellholder is mangling your brass..but I doubt it after 7k rounds through your HK.



I suppose the magical brass gremlin is a distant possibility......but I'd say its fairly distant.

 

[918v]

Are you lubing the inside of the case neck before sizing? If you're not, then the expander ball will pull the shoulder forward on the way out and change the headspacing.

 

[steve4102]

Take one of the cases that fail the case gauge and will not chamber.

Place it in the shell holder.

Screw the die into the press a little at a time until it does chamber.

Lock the die down.

Done.

All cases should chamber now.

 

[243winxb]

There are shims for the die bushings & sub plate, supplied by Hornady.(online info) Call them and ask. Over at AR15.com, they shim where the sub plate meets the ram. Not all presses need them. This keeps the sub plate from flexing, so you can FL size bottle neck cartridges. Google it.

 

[NeuseRvrRat]

Are you lubing the inside of the case neck before sizing? If you're not, then the expander ball will pull the shoulder forward on the way out and change the headspacing.

this was my first thought

 

[Walkalong]

I have had two .223 sizers. Neither one would push the shoulders back enough to pass my Wilson case gauge even with them had against the shell plate on my LNL. I had to take a little bit off the bottom of both sizers. This was with once fired brass that was not work hardened at all.

LNL issue? Freak thing that I got two sizers doing the same thing? Who knows

Get something to check how far back you are moving the shoulder. Make sure it is not a ever so slightly buckled shoulder or bad case head/rim holding it out.

Make sure the expander ball is not pulling the neck forward. This is easy to check with the expander out of the die. I like to use carbide expander balls on non bushing dies.

Eliminate all possibilities before shortening a sizer.

 

[dbarnhart]

Walkalong: Thank you. Your Wilson case gauge and my Dillon case gauge are identical, so at lest I know I'm using the right tools.

This morning I switched back to the Rock Chucker and sized 10 rounds on it instead of the LnL. It made no difference, so I don't think the problem is caused by any flexing of the LnL's shellplate or subplate.

It will be interesting to see where this leads me.

 

[NeuseRvrRat]

on the rockchucker, did you have the die setup so that the press would "cam over" at a full stroke?

also, are you putting a little lube inside the case necks?

 

[dbarnhart]

on the rockchucker, did you have the die setup so that the press would "cam over" at a full stroke?

also, are you putting a little lube inside the case necks?

Thank you. I had not set the Rockchucker to cam over. And now that I think about it perhaps I did not lube the inside of the case necks of the first rockchucker batch.

So, with a little more cam-over and making sure to lube the inside of the case necks I created 8 cartridges and all 8 fed nicely.

Now it's time to start narrowing things down to find the real problem source.

 

[BADUNAME37]

I bought a real tiny bottle of something called Motor Mica. It is for dipping the case mouth-neck into so the expander button does not pull so hard coming out, which has a tendency to stretch the shoulder a bit, making some cases chamber a bit harder than normal.

 

[BADUNAME37]

MidwayUSA, Motor Mica.....

http://www.midwayusa.com/Product/290522/frankford-arsenal-fine-powdered-mica-4-oz

 

[243winxb]

Shell Plate

Shell Plate should be tight as possible to the sub-plate (if like my old Dillon) The Shell Plate measurement should be no thicker than .125" same as a shell holder. Check each station, as each one can be different. (If like my old Dillon)??

 

[dbarnhart]

Progress: After checking with Hornady's customer support, I put the RCBS sizing die back into my LnL and set the depth of the die to require a little cam-over at the end of the stroke. This time the sized cases came out with the appropriate amount of shoulder setback.

So I'm getting somewhere.

 

[Walkalong]

A die that just touches the shell holder with no brass in it, will not touch it when actually sizing brass. It has to be set up while actually sizing brass.