223 Sizing Issues

[Rwskinner]

I'm still having very inconsistent readings when FL sizing with my Dillon 223 die. First, my once fired cases from my gun measure 1.455" and my target is to size and bump back 1.450" (for multiple AR's).

The problem I'm having, is my measurements are coming our all over the place. I took a handful of cases which were 1.760" so I know they would get bumped back. Some come out at 1.445" to 1.458".

LC brass seems to fall really close to 1.450"
PPU brass comes out around 1.455" - 1.458"
Most of my commercial 223 brass comes out short at 1.445"

Measurement is from Base to Datum.

I removed my depriming pin and the carbide expander to make sure I wasn't stretching the necks on the way back out and the results were pretty much identical.

That is a large variance. Is this something I'm doing wrong or is there typical with different makes of brass in that some springs back more than others?
Is sorting head stamps the only cure?

Richard

 

[Walkalong]

The length of the case has nothing to do with whether the shoulder will get moved back when sizing, but yes, that is a very large variance from base to datum.

It makes me wonder if you have the sizer screwed down enough. When the brass is going up in the sizer, the first thing to happen is the body is squeezed inward, pushing the shoulder forward. The shoulder is not pushed back until it contacts the shoulder in the die.

Double check this.

 

[Rwskinner]

Sorry, this was a typo. <I took a handful of cases which were 1.760" > It should have been 1.460". Using the Hornady adapter for my calipers, that is the measurement from the base to the datum line (0.330"). I wanted to make sure they were longer than my target value for adjusting the die.

I can indeed screw the die down further to see what happens but any adjustments I've made downward seems to just bump the shoulders back further. It's bumping them back 0.002" to 0.15" already.

How I originally set the die, was to let the press slightly cam over then slowly back the die out a little each time to reduce the bump back to where I wanted it then locked it down.

Richard

 

[Rwskinner]

Okay, with the shell plate all the way up, I screwed the die down until it touched then went down another 1/4" turn to make it cam over. For grins I ran a handful of each brass mfg thru.

LC 1.440"
PPU 1.450"
FC 1.438"

These indeed chamber fine but I guess my question is why the variance? Spring back from harder brass in the PPU? The PPU are some of the few that show signs of be flame annealed. What is bad, the PPU was new loaded ammo shot thru my gun!

The only other thing I know to do is pull out all the PPU and then set my die for the bump back I want. It seems the LC and FC and "others" are within a couple thou of being where I want my shoulder for minimum stretch. I could then later run the PPU with different die settings if I wanted or needed to.

Richard

 

[Walkalong]

Well, brass hardness does affect the bump, but that is a big variance either way.

Another option is to anneal them all. Might be the best answer.

 

[gshipps]

Just for kicks take anything over your target range and run it again at the same setting. I do this on my 550 by having the sizer/trim die set the same as FL sizer die. Seems to make for more consistent sizes for me.

 

[steve4102]

It's bumping them back 0.002" to 0.15" already.

A Hundred and Fifty Thousands is a typo, yes?

 

[243winxb]

The XM193 Federal factory nato ammo will expand fully to the chamber on the first firing, with very little spring back.

 

[carbine85]

Could it be play in the shell plate or shell holder?
Or could it be the way you are lubricating the cases?

 

[moxie]

I'm not sure I understand the point of this extra effort. Why not just size and trim? Will the resulting rounds not work properly in multiple ARs? As long as the trim to and OAL are correct, they should be just fine. I use range brass with a myriad of headstamps,, lots and production years, and never have any problems chambering the completed rounds.

Absent chambering problems, what's the point of trying to adjust head to datum line measurements?

 

[Walkalong]

Headspace issues.

 

[moxie]

But what issues will this solve, especially with ARs that are notorious for NOT having headspace problems?

 

[243winxb]

223/5.56

Moxie, a large chamber with maximum sizing of the brass, may produce as much as .015" head clearance. One is brass, the other is chamber. But have to much slop in one or the other and you get the same results, case separation. I agree that its mostly a waste of time for a standard AR15 trying to get the perfect head to datum measurement when using a single stage press. Different story with a progressive. Here a L E Wilson gage comes in handy.

 

[Walkalong]

But what issues will this solve, especially with ARs that are notorious for NOT having headspace problems?

Artificial headspace created by pushing the shoulder back too far inducing too much clearance between the case head and the breech when the shoulder is all the way forward in the chamber.

http://www.thehighroad.org/showthread.php?t=734058
.

 

[Rangemaster]

Use a sharpie pen and mark your shoulder on the brass. So you can see if your even touching the shoulder.

 

[moxie]

Thanks guys, I understand all that, in theory. But in practice (assuming the dies and/or the rifles' chambers aren't really wonky), it sounds like a quick run down the OCD rabbit trail.

Again, absent chambering problems, why bother? (Rhetorical question here.) Has there been any incipient or actual case head separation in cases fired in one or more of the OP's rifles?

 

[Walkalong]

Dunno, but if his measurements are correct, he has cases with shoulders pushed back .012 than others. That's a lot.

LC 1.440"
PPU 1.450"
FC 1.438"

I do understand your point though, as most people never measure anything, and many of those just screw the sizer all the way down, and, thankfully, good dies and properly made firearms keep them out of trouble.

 

[mtrmn]

I've seen on another forum that some have helped this problem by using a bit more lube when sizing--OR making sure the lube used is distributed more evenly.
Myself--I size all my cases on a single stage and only use the progressive AFTER all the brass prep is done. The fact that I don't even check the headspace at the datum makes most people cringe. I DO use a JP case gage that is made with an actual chamber reamer to check each round before it goes into the "ready" pile. I have about 8 or 10 ARs in the family and my ammo has to work in all of them.

 

[119er]

I just bought a case gauge to eliminate all the guessing and time wasting on while loading my high volume .223. I separate by case manufacturer and set the die for the case to be flush with the top of the gauge. No problems since.

 

[Reloadron]

Sorry, this was a typo. <I took a handful of cases which were 1.760" > It should have been 1.460". Using the Hornady adapter for my calipers, that is the measurement from the base to the datum line (0.330"). I wanted to make sure they were longer than my target value for adjusting the die.

I can indeed screw the die down further to see what happens but any adjustments I've made downward seems to just bump the shoulders back further. It's bumping them back 0.002" to 0.15" already.

How I originally set the die, was to let the press slightly cam over then slowly back the die out a little each time to reduce the bump back to where I wanted it then locked it down.

Richard

Something you may want to keep in mind is while The Hornady Lock-N-Load Headspace Gage 5 Bushing Set with Comparator can be a useful tool it can also be prone to some error. Using the gauge to measure a case is like using any other similar gauge, a matter of feel. To illustrate what I am getting at take a look at the below image:



Pictured above is The Hornady Lock-N-Load Headspace Gage 5 Bushing Set with Comparator, a RCBS Precision Mic 223 Remington, and a set of three 223 Remington chamber headspace gauges. The headspace gauges are dimensioned as follows:

Go = 1.464"
No Go = 1.467"
Field = 1.470"

How do I know the accuracy of the headspace gauges? Prior to my recent retirement from my job I dragged much of my gauging into work and had the guys in the CMM (Coordinate Measuring Machine) areas check my gauging. When a few million dollar Zeiss CMM says my $25 gauges are accurate I accept it as gospel.

Running the 1.464" Go gauge in the Hornady gauging I get 1.459" and that number repeats. Take the gauge down, reassemble and set up again, same number. Over and over again the same 1.459". So it repeats but is off by -.005" of error. Just the nature of the beast with this type gauging. The upside is with a price tag of under $40 you can measure a mountain of calibers.

Pictured on the bottom of the image (left) is a RCBS Precision Mic Gauge. While the RCBS kits are much more expensive I really like them and prefer using them. When I measure the same Go gauge I get 1.464" every time, exactly as I should. It repeats and is accurate. Well within .001" which exceeds anything I'll ever need.

Just a matter of how OCD we want to get over the numbers but in my opinion and just my opinion I would not place too much weight in the numbers you get from the Hornady gauge.

Moving along here is another image:



A few weeks ago I fired these rounds from one of my AR rifles at the range. Federal American Eagle run of the mill 223 ammunition. The spent brass on the right was resized (full length) with measurements taken before and after.

Unfired dimensions:
New Case Length = 1.740" as measured using vernier caliper.
Case Headspace = 1.464" as measured using the RCBS gauge.
Case Headspace = 1.459" as measured using Hornady gauge.

Once fired:
Case Length = 1.745" as measured using vernier caliper.
Case Headspace = 1.469" as measured using RCBS gauge.
Case Headspace = 1.464" as measured using Hornady gauge.

Note: The change was identical (.005") on both gauges. So while the Hornady gauge gave what I believe an inaccurate start the delta is right on the money.

The once fired numbers are an average of the 5 cases pictured but overall the deviations were only about .001". Not bad at all.

I resized the brass using RCBS aerosol case lube including a swab in the necks. Using a Rock Chucker and RCBS 223 full length dies I raised the ram and screwed the die down till it bottomed out then added 1/8 turn and locked the die. That got me right back to where I started at 1.464".

I also use and like the Wilson gauges for a quick check of my cases, a nice simple Go or No Go. I have just learned from experience and some comparisons not to place too much stock in the Hornady numbers. Hell when I do 308 Winchester my 1.630" precision Go gauge reads 1.623" (-.007") using the Hornady gauge while my RCBS 308 gauge reads 1.630".

The bottom line here is you need to know the numbers you get from your gauging are good numbers. I distrust the accuracy (not the repeatability) of the Hornady gauges for the reasons I mentioned. How much does it all matter? Really depends on how OCD you want to get with measuring cases. When I load 223 for match grade ammunition using Lapau brass and hand weighing each charge I can get pretty OCD about things.

Just My Take
Ron