.223 sizing & headspace question

[Bexar]

I just sized some new unfired Remington .223 brass. I followed SOP and set the resizing die to the shell holder than slightly more to get the camming action.

I ran about 20 cases through and thought I'd better check them on my RCBS Precision headspace mic. The cases are all .004 under the ANSI minimum. IE...1.4636 my resized cases are 1.4596

I had to stop after 20 cases because of arthritis but when I restart should I adjust the dies to minimums or finish the other cases at this to maintain consistency?

Is this .004 setback critical for too much headspace or are we still safe?

They are to be fired in our Daughter's new AR-15 with the 5.56 chamber.

I'm guessing we're looking at a .005 to.006 case expansion in the chamber.

The only thing I could have her do is fire five factory rounds to get the chamber actual headspace specs.

Any opinions or advice?

Thanks...Bexar

 

[gamestalker]

I have several presses, and one of them, which is the Reloader Special (RCBS) made in 1981, is a cast iron "O" frame, so it's very rigid. But it full strike it acts differently than my RC. or my smaller cast aluminum "O" frame Reloader Special 2. It stops very abruptly at full stroke when resizing, so there is very little camming effect felt, which makes it rather prone to short stroking if I'm not careful.

Maybe that's similar to what your dealing with? Does your press let you know you've fully extended it, other than just coming to an abrupt stop? Now I kind of prefer that press, cause when I'm doing precision bumping or really any operation, it will produce dead on with .000" variance repeatable results. But if I'm not consciously following through with each stroke, I end up with a few that end up having to get run through a second time.

The other thing I've experienced, and I'm not sure if this is a brass thing or a press thing, but I'm thinking a little bit of both, considering it's happened on all my presses. I call it soaking the brass in the die, in other words, when the brass is fully pressed into the resizing die, I let it sit there for a second or three. Some brass just spring back more than others, it seems to work for me in those situations. I figure it's either become work hardened, or it's just springy, or maybe just thicker brass.

The aluminum "O" frame RS2 is a very springy press, not very rigid. With that press I have to let the brass soak for several seconds to compensate for the spring back in the press. I don't use that press a lot for bottle neck, but when i need a portable press, that one is lighter and easier to haul around.

Well, that's all I got. I hope I helped in some way

GS

 

[Reloadron]

I just sized some new unfired Remington .223 brass. I followed SOP and set the resizing die to the shell holder than slightly more to get the camming action.

I ran about 20 cases through and thought I'd better check them on my RCBS Precision headspace mic. The cases are all .004 under the ANSI minimum. IE...1.4636 my resized cases are 1.4596

I had to stop after 20 cases because of arthritis but when I restart should I adjust the dies to minimums or finish the other cases at this to maintain consistency?

Is this .004 setback critical for too much headspace or are we still safe?

They are to be fired in our Daughter's new AR-15 with the 5.56 chamber.

I'm guessing we're looking at a .005 to.006 case expansion in the chamber.

The only thing I could have her do is fire five factory rounds to get the chamber actual headspace specs.

Any opinions or advice?

Thanks...Bexar

I would not worry about it too much and here is why. While the RCBS Precision Mic is a cool tool they are not always an accurate tool. I happen to have two of them sitting here. The only way to know if the gauge is telling the truth is to check the gauge against a known standard. A nominal case in 223 Remington is 1.4636" or lets say 1.464". Using the first gauge I measure a Forrester Chamber Headspace Gauge (A known chamber gauge). My first gauge reads 1.634", I now measure using my second gauge and it reads -.0025. In this case because I have a known standard of comparison I know which gauge is, to use a technical term, dead on balls accurate. I also know which gauge is reading about -.002 from nominal. This is not all that unusual.

If you were to read back through these forums on related threads we have forum members who have found gauges actually reading as much as -.006 from nominal and a few + readings from nominal also. The same has held true for the Hornady Lock N Load Headspace Gauge Kit so this is just not common to the RCBS gauges.

Now if I fire 10 factory rounds and I measure them before and after I know I can set my shoulder back by adjusting my sizing die. I also know the fired cases are a pretty good indication of what my chamber is. Anyway I wouldn't let the numbers you got worry me. Measure some new quality 223 and see what you get. My experience has been that new factory ammunition is generally pretty close to dead on balls accurate at 1.464". See what your gauge tells you.

Ron

 

[steve4102]

After you fire this New brass, double check your sizing with the once fired cases.

Size a few cases and see if they chamber and extract with ease before loading a bunch of ammo, only to find that your sizing die was not set up correctly for YOUR chamber. Use the chamber, not the gauge.

 

[243winxb]

AR-15 with the 5.56 chamber.

This is ask alot, so ...... Fire this ammo to measure the Head to Datum with a comparator . The high pressure will expand the fired brass to almost chamber size. >

[/URL][/IMG] NOTICE: While the 5.56x45mm NATO will fit in a .223 Remington chamber, the 5.56 is a military round that runs at higher pressures than its .223 counterpart and is not recommended to be fired in a .223 Remington chamber.

 

[Reloadron]

@ 243winxb,

I know all of my 223 and 5.56 chamber sizes. They are all smaller than a bread box!

On a more serious note good on target info in that post.

Ron

 

[Bexar]

I would not worry about it too much and here is why. While the RCBS Precision Mic is a cool tool they are not always an accurate tool. I happen to have two of them sitting here. The only way to know if the gauge is telling the truth is to check the gauge against a known standard. A nominal case in 223 Remington is 1.4636" or lets say 1.464". Using the first gauge I measure a Forrester Chamber Headspace Gauge (A known chamber gauge). My first gauge reads 1.634", I now measure using my second gauge and it reads -.0025. In this case because I have a known standard of comparison I know which gauge is, to use a technical term, dead on balls accurate. I also know which gauge is reading about -.002 from nominal. This is not all that unusual.

If you were to read back through these forums on related threads we have forum members who have found gauges actually reading as much as -.006 from nominal and a few + readings from nominal also. The same has held true for the Hornady Lock N Load Headspace Gauge Kit so this is just not common to the RCBS gauges.

Now if I fire 10 factory rounds and I measure them before and after I know I can set my shoulder back by adjusting my sizing die. I also know the fired cases are a pretty good indication of what my chamber is. Anyway I wouldn't let the numbers you got worry me. Measure some new quality 223 and see what you get. My experience has been that new factory ammunition is generally pretty close to dead on balls accurate at 1.464". See what your gauge tells you.

Ron

Federal new soft point was spot on to -.002 below minimums. Winchester factory surplus M855 was consistently -.002.

After getting those -.002 readings I did become somewhat suspicious of the new RCBS Precision mic.

Assuming the mic is correct...and I appreciate Ron's input is .-004 enough to be concerned about? This is new Remington bag of brass. Ron doesn't think so that brings a little comfort. Thanks Ron.

 

[higgite]

I ran about 20 cases through and thought I'd better check them on my RCBS Precision headspace mic. The cases are all .004 under the ANSI minimum. IE...1.4636 my resized cases are 1.4596

Your cases are fine. The 1.4636" measurement is the minimum chamber spec, not the minimum cartridge spec. Minimum cartridge spec is 1.4596".
http://www.saami.org/pubresources/cc_drawings/Rifle/223 Remington.pdf

However, for semi-auto (AR-15) fodder, I set my sizing die to just firmly touch the shell holder with the ram all the way up. This generally gives me a headspace measurement on the order of 1.463", about mid-range of the SAAMI cartridge spec. I haven't had any feed problems in multiple AR's with the die set there and the resizing doesn't work the brass as much as it would if set to minimum cartridge spec. ymmv

 

[Reloadron]

Your brass is fine. I wouldn't worry about it at all. Pretty much covered in higgite's post above. Choot and enjoy.

Ron

 

[Bexar]

Thanks guys...thanks.

 

[W.E.G.]

I'm glad to see you are using the RCBS Precision Mic.

Its a great tool.

I prefer to push the shoulder on my sized brass be no more than 0.002" further than the dimension for a "GO" chamber gage.

Your brass is 0.004"
Definitely shootable, but I would back that off a couple thou the next time.