*Updated* .223 headspacing issues with Dillon dies?

[Gadsden]

All,
In order to fine-tune my headspacing on my .223 reloads I invested in a RCBS precision mic:
http://www.midwayusa.com/product/477756/rcbs-precision-mic-223-remington

To set up a control environment, I checked 20 factory-loaded Remington .223 rounds.. all perfect zero in the device. I fired 10x in two different (and relatively new) uppers (carefully keeping the fired brass separate to know which is which), took them home and measured them. Both sets had their headspace stretched by .001 from factory. So far so good, that makes sense.

When I set up my Dillon carbide .223 FL resizing die into my D550B and sized the brass there was no change in the headspace.. even after screwing the damn die all the way down to where it makes contact with the shellplate. I marked up the neck on piece of brass and sized it, I could not see that the resizing die is hitting the shoulder of the casing... just the neck. This is a full-length die, not a neck only.

To re-test this, I found some fired brass that had been used in a friends upper. It measured +.005" in the RCBS mic. I sized it in the screwed-all-the-way-down resizing die then re-measured it. No change in the headspace.. It still measured +.005" in the RCBS mic.

Am I doing something wrong here? I was under the impression that the headspace can be bumped down by screwing the die down slightly. If this is the chase is it possible that my die is not to tight enough tolerance?

 

[EddieCoyle]

I know this won't help you, but...

I had this happen once in a single stage press using an RCBS die and a Lee shellholder. The shellholder was too thick, so when it contacted the bottom of the die, the case wasn't being pushed in far enough to bump back the shoulder. I solved the problem by lapping some material off the top of the shellholder so it could push the case in farther.

Since you're using Dillon dies and a Dillon press, I would think that you should be able to get acceptable results. Do the sized cases chamber OK?

Do you have another sizing die to try in the press? Do you have another press (a single stage) where you can try the die?

Is there any way you can screw the die down farther? On some of my setups, the die has to cam over (so I can feel the shellholder contact the die even without a case present).

Are you using lube?

 

[Gadsden]

I know this won't help you, but...

I had this happen once in a single stage press using an RCBS die and a Lee shellholder. The shellholder was too thick, so when it contacted the bottom of the die, the case wasn't being pushed in far enough to bump back the shoulder. I solved the problem by lapping some material off the top of the shellholder so it could push the case in farther.

Since you're using Dillon dies and a Dillon press, I would think that you should be able to get acceptable results. Do the sized cases chamber OK?

Do you have another sizing die to try in the press? Do you have another press (a single stage) where you can try the die?

Is there any way you can screw the die down farther? On some of my setups, the die has to cam over (so I can feel the shellholder contact the die even without a case present).

Are you using lube?

Thanks for the quick reply!
That is helpful.. it re-assures me I am not completely insane as I thought the same thing on lapping the bottom.
The rounds chamber perfectly fine.. I've loaded over 1000 through that die w/o issue. I was just trying to get all OCD and have complete control over the headspace in order to enhance the accuracy of the rounds or return the rounds to as close to spec as possible.
I only have the dillon press/die set, so I'm stuck with what I have so far. I did think about ordering another die, but I wanted to get a sanity check first.
I don't think I can screw the thing down lower, I can feel it contact on the downstroke as it is. I was leery about breaking something.
I did not lube the round, as I was being lazy since it was just one round in a carbide die. I can try that tonight. Would that make much of a difference?

 

[jasons]

Do the sized cases pass in a SAAMI gauge? If so the die is "in spec." Personally "in spec" isn't necessarily good enough for me and I'd look for a different sizing die. (Or lap a bit off the base as EC mentioned.)

 

[Gadsden]

Do the sized cases pass in a SAAMI gauge? If so the die is "in spec." Personally "in spec" isn't necessarily good enough for me and I'd look for a different sizing die. (Or lap a bit off the base as EC mentioned.)

Yup, they pass the gauge fine. From what I read, adding 0.005" to the headspace is still in the range. I'm just trying to completely control it.

 

[jasons]

I'm just trying to completely control it.

I'd be doing the same. I'd lap about .005" or whatever off the base of the die so that it sizes to SAAMI minimum and then adjust out from there. For what it's worth I use Forster dies and you can adjust them to size way under SAAMI if you wanted to for some reason.

 

[Gadsden]

Talked to Dillon, they said to run the die down up to a quarter turn past where it hits the shell plate. I was hesitant to do that in fear it would break something, but I will give that a try as soon as I can. He also said that it will be a royal PITA to lap the carbide die due to the hardness of the metal.

Sound about right?

 

[highscore]

I load .223 in my Dillon and I can get to minimum. I don't like pounding my press more than need be so I would just grind off the bottom of the die if necessary. Easy for me to say because I can do it myself. I'm sure Dillon will help or you can get someone to grind it for you. I'm not a true believer of pushing back the shoulder any further than need be and have been known to size more towards the middle of the spec.

 

[highscore]

Yes, lapping .005 would be a PIA. Grinding would take no time at all. If you want to do it and can't find anyone local at the right price to do it, ask.

 

[EddieCoyle]

Try cranking it down 1/2 turn. You won't hurt anything.

 

[Patriot]

And the solution was?

 

[Gadsden]

Try cranking it down 1/2 turn. You won't hurt anything.

Exactly what I just did, worked like a champ! Actually, went way too much, so I backed it off and found my sweet spot.

Thanks again for the tips, I learned a lot with this experiment!
I have to say, the RCBS precision mic is a sweet little tool.. will have to get one for .308!

Last question: will different types of brass resize slightly different? I had some different brass that actually ended up a couple thousandths under spec, while the other stuff was a couple thousandths over.

- - - Updated - - -

And the solution was?

Heh.. wife came down before I could finish posting the response.

 

[EddieCoyle]

Last question: will different types of brass resize slightly different? I had some different brass that actually ended up a couple thousandths under spec, while the other stuff was a couple thousandths over.

My experience has been that if the brass is all the same headstamp, same number of times fired, and came out of the same rifle, then it all sizes the same. Are you sure those cases weren't short before going through? Also, if the rims are bent, funny shit can happen in the die.

If all you're interested in checking is headspace, instead of getting a precision mic for each caliber just get a Hornady headspace comparator kit. For less than the price of one RCBS Precision Mic, you can check virtually any caliber.

 

[Gadsden]

My experience has been that if the brass is all the same headstamp, same number of times fired, and came out of the same rifle, then it all sizes the same. Are you sure those cases weren't short before going through? Also, if the rims are bent, funny shit can happen in the die.

If all you're interested in checking is headspace, instead of getting a precision mic for each caliber just get a Hornady headspace comparator kit. For less than the price of one RCBS Precision Mic, you can check virtually any caliber.

The "control" set of brass was all the same: factory new, fired out of the same rifle, measured as spec before firing. It all sized the same. The other brass was fired 3 times and they were different head stamp. They re-sized a tiny bit different. That's what led me to the question about the headstamps.

I saw the Hornady kit after I bought the RCBS.. kinda wish I went that route just to save money since I will be doing .308 as well but I also gotta admit that I like the RCBS's design. Thanks for the tip and continued input!

 

[Gadsden]

Interesting twist..
Set up the sizing die, sizing to +0.001; rifle headspace is +0.003. Sizing is consistant. Made a couple dummy rounds (rounds with no powder or primer, but has bullet and seated to proper OAL), measured them again, still +0.002. Chambered the dummy round, chambered fine. Measured the dummy round in the rifle and re-measured... round now measures -0.002!

Could chambering in the rifle actually set the headspace back -0.001-2, or am I just over-thinking this whole thing? I had this measurement change on two different dummy rounds in the same rifle.

Thanks for the input!

 

[Jasper]

is this for an AR15? or a bolt gun?

for a semi auto, you want to size brass at *least* 0.003-4" UNDER fired dimensions. I usually measure 5-10 pieces of brass, take the average, and bump it back 4 thousandths.

for a bolt gun, 0.002" is fine


and yes, an AR15 will EASILY crush the shoulder upon chambering. there's quite a bit of force behind the BCG when it slams home.

it is odd that your rifles chamber would be 2thous under SAMMI "0" though. What kind of rifle?

 

[Gadsden]

is this for an AR15? or a bolt gun?

for a semi auto, you want to size brass at *least* 0.003-4" UNDER fired dimensions. I usually measure 5-10 pieces of brass, take the average, and bump it back 4 thousandths.

for a bolt gun, 0.002" is fine


and yes, an AR15 will EASILY crush the shoulder upon chambering. there's quite a bit of force behind the BCG when it slams home.

it is odd that your rifles chamber would be 2thous under SAMMI "0" though. What kind of rifle?

Got ya, thanks.
Its an AR-15, match barrel, chambered in .223 (not 5.56).

 

[Jasper]

what kind of match barrel? like a WhiteOak / CompassLake? or an off-the-shelf "match" barrel.

223/556 is kind of universal, unless you specifically ordered it chambered in 223 (which ive never actually seen)...the more common "match" chambers are Wylde and Frank White's "CLE" chamber (which requires smallbase dies to get your brass to fit back into it)

 

[Gadsden]

what kind of match barrel? like a WhiteOak / CompassLake? or an off-the-shelf "match" barrel.

223/556 is kind of universal, unless you specifically ordered it chambered in 223 (which ive never actually seen)...the more common "match" chambers are Wylde and Frank White's "CLE" chamber (which requires smallbase dies to get your brass to fit back into it)

Bushmaster DCM/CMP upper.
It is similar to this one:
http://www.midwayusa.com/product/98...ee-float-handguard-a2-front-sight-flash-hider

I thought it odd that it would measure under spec after chambered as well. The fired brass measured a bit over spec, but when resized, seated, and re-chambered it did change a bit below. I was just chalking it up to the violent action of being chambered.

 

[Jasper]

Bushmaster uses their own "hybrid" chamber. IIRC, it's a .223 chamber, and the leade is cut to accomodate 5.56. short answer, you can run 223 OR 556 in it


why BM decided to design their own wylde-like chamber is beyond me.

either way, your fired (or chambered) cases shouldnt be coming out @ 2thous under SAMMI 0. something is amiss here. chamber clean? brass clean? (leaving case lube on the cases can *sometime* cause stuff like this. My WOA barrels all spit out brass @ 0.002" over SAMMI "0", so I size back to 0.002" under "0".

 

[Gadsden]

Bushmaster uses their own "hybrid" chamber. IIRC, it's a .223 chamber, and the leade is cut to accommodate 5.56. short answer, you can run 223 OR 556 in it


why BM decided to design their own wylde-like chamber is beyond me.

either way, your fired (or chambered) cases shouldnt be coming out @ 2thous under SAMMI 0. something is amiss here. chamber clean? brass clean? (leaving case lube on the cases can *sometime* cause stuff like this. My WOA barrels all spit out brass @ 0.002" over SAMMI "0", so I size back to 0.002" under "0".

Chamber could probably used a cleaning, but should only have around 10-20 rounds through it since last cleaning (all brass). Fired brass is a bit over.. it was after being chambered, ejected, and re-measured that it was a couple thousandths under spec.