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I think I understand the guages and their headspace measurement along with measuring of fired cases to get an idea of individual chamber headspace. Admittedly my googiefie is suspect, and I haven't spent much time looking, but on the unfired ammo itself, I cannot find "headspace" max/mins. Just distance of shoulder breaks from the base.
Would someone please straighten me out and educate me as to the minimum headspace for unfired 223 and for 556 ammo? Thanks
Apologies for my post. Didn’t fully understand where OP was headed or asking…
I’m understanding a lot from the dialogue. Thanks!
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Most factory ammo is produced with the case being minimum dimensions. That is to say the cartridges are dimensioned is such a way that they should chamber and function in the vast majority of commercially produced .223/5.56 chambers.Quote:
Originally Posted by triggerjerk
You can verify this with a case gauge, and you will find virtually all new cartridges will be flush with the “low step” of the headspace indication on the case gauge. Indicating their minimum length for safe headspace.
If you’re feeding a semi-auto this is what you want because the minimum headspace loaded rounds ensure better feeding reliability.
If you’re loading for a bolt action you can full length resize to set the shoulder back .002”-.003” from your fired case shoulder reading. So if you nominally have .006” worth of room to play with for a perfectly in the middle in spec chamber and your minimum headspace factory ammo grows .006” and then you resize the body and set the shoulder back another .002”-.003” you end up with a bit less clearance and less brass expansion. It might help accuracy a smidge too at the cost of not being able to run it in other chambers.
Coal Dragger's correct. Factory ammo is made to function properly in as many chambers as possible, so it's set to the minimum.
Are you're setting headspace yourself on a bolt gun?
For bolt guns, I bump the shoulder back on fired brass .001-.002"
Semi autos my require more, as much as .006" bump, as they tend to stretch quite a bit. I take new factory ammo, measure and fire it, then measure again. The difference is what I usually set the sizing die to bump.
Been using Redding extended shell holders to get head space of reloads within two or three thou of chamber headspace for my bolt guns for decades. I had quit using standard neck dies and went back to full length dies/ext holders because I could spin neck sized cases and see a greater lack of concentricity.
Again, those cartridge diagrams show diameters and distances to breaks in the shoulders, but no one gives minimum headspace spec for ammo as a distance from the base to a datum point on the shoulder like it is specd for a chamber (min, max, OMG or go, no go, field). Obviously max ammo headspace needs to be just shorter than or right at the go gauge headspace. But what is the "minimum" ammo headspace spec in same units used for chamber headspace measurement? In another thread, mention of excessive headspace between ammo/chamber leading to problems was mentioned, and I realized I'd never run across minimum headspace spec for ammo, itself. If I'm not making sense, we can just let this thread go as I'm just curious and have had no problems so far (knock wood).... Know I do 'preciate ya'll.....
Definitely. Not so much for .223, but 6.5, 308, and 300WM for sure. I get a decent amount of partial case separations in 6.5 because it's sized to run in 3-4 guns. Ideally you'd have a die and brass for each individual rifle, but our shooting is so disorganized, it's impossible to do things right.Quote:
Originally Posted by grizzman
I reload "mostly" for Auto's and I want my rounds to work in any rifle I am shooting. I don't reload for specific rifles, I have too many for that to be a reasonable thing to attempt.
I learned a long time ago, to check my brass after sizing with one of these. Pulling and re-re-sizing a hundred rounds isn't fun.
Lyman Headspace / Case Length Gauge
Tells me if my cases are sized correctly and that I have trimmed them to within spec.
In loading for "automatics", have y'all done any headspace/bullet seating measurements on factory and reloads before and after chambering to see what effect the "violence" of chambering has? I believe it also takes some math to determine actual bullet movement in the neck because of headspace change..... (And I don't have anything to measure runout with so haven't done that...)
This ^^^Quote:
Originally Posted by HKGuns
I have both a Hornady cartridge gauge and the superior Sheridan Slotted Ammo Gauge. I use the Hornady for quick checks on all my reloads, and the Sheridan Slotted one to determine where the hang-up is, and then correct it.
I could get by with just the better Sheridan, but I bought that one last.
https://sheridanengineering.com/prod...unition-gauge/
I bought these awhile ago for all my bolt guns and they seem to be working pretty good. Not really cheap but its a buy once cry once kinda thing I guess. I have been setting my shoulder back .002 and everything seems to be working good. https://www.whiddengunworks.com/product/case-gauge-3/ Wilson case gauges are a great tool also,especially for the semi-auto rifles. https://lewilson.com/case-gageQuote:
Originally Posted by MarshallDodge
Just to be clear, so people don't get confused.Quote:
Originally Posted by m1a_scoutguy
"Bumping the shoulder .002 ONLY works reliably when you are measuring and bumping the case fired from the rifle you're reloading for.......You may get lucky, but eventually, your luck will run out.
That isn't how I load.....I load, as stated above. Every round fired may have been fired from a different gun or not by me......I load in lots of 100 at a time and I could grab any box and use it with any rifle.
Which is exactly why I take them down to fit into the case gauges.
Yes,you are correct,I should of been more clear. I use these for specific rifles in each caliber I have and use only brass that has already been fired out of that bolt gun. You do not want to just pick up range brass or even buy once fired brass and trust this setup. ONLY after running it through your specific rifle.Quote:
Originally Posted by HKGuns
No, I have not. With a properly loaded cartridge, chambering into a rifle once should have no affect on the shoulder location or cartridge overall length.Quote:
Originally Posted by triggerjerk
Any 5.56 ammo I make is loaded so that it's usable in any of my ARs. Any semi-auto 308 Win ammo I make is also loaded so that it's usable in any of my semis, or bolt guns. Bolt guns have ammo that is specifically made for them, and not used in other rifles.
I don't know of a minimum headspace measurement for 5.56. Unless you're installing a barrel on a rifle that doesn't have fixed headspace due to the rifle's design, it's generally not something that matters.....since headspace isn't the same for all rifles.
As I said, for me, 3 rifles of differing headspace. Shorter chamber with blue/h2 and 4 thou longer chamber with white/h both pushed shoulder back same distance. 2nd chambering pushed longer victims back that last thou to shorter hs. 2nd chambering did not push those shorter from 1st chambering at all. Factory PMC, American Eagle, Monarch Brass and handloads (un-annealed)......
Both the cartridge and chamber are specified in the SAAMI prints.
You can see there the 5.56/223 chamber headspace min dimension is 1.4636 +.010
The Cartridge headspace dimension is 1.4666 -.007
A little careful math will reveal that for most cartridges, there is potentially .003 of "crush" built into the design.
In other words, the max cartridge is .003 longer than the min chamber.
Although this seems fundamentally wrong for an autoloader, in practice, most factory ammo is made toward the minimum spec of .007 shorter, which provides .004 of clearance rather than .003 of interference.
The short version of all that is, yes the min/max values are right in the prints.
https://d2j6dbq0eux0bg.cloudfront.ne...4131029927.jpg
Quote:
Originally Posted by triggerjerk
Can I ask where you got that drawing Clint? Never seen one done like that before with both on one drawing.Quote:
Originally Posted by Clint
Thanks, Clint. If you hadn't specifically said it was on that drawing, I wouldn't have found it, glasses or not, on my grainy magnified phone image. Maybe I should get my computer fixed.... Nah, need more ammo/equipment....
Best I remember (it's been a few years) I was amazed that all the factory ammo measured right at that 1.4636 go guage....
They're all right from the SAAMI web site and all in that format.
https://saami.org/technical-informat...mber-drawings/
https://saami.org/technical-informat...ami-standards/
Interestingly, Hornady did a good job with the 6ARC and others to eliminate the potential headspace overlap.
You'll see the headspace is 1.190 and 1.1901 to guarantee NO overlap if both are in spec.
https://saami.org/wp-content/uploads...2020-07-29.pdf
Quote:
Originally Posted by HKGuns
Got them thanks. For anyone else interested, the other than new or modified cartridges are all in one of the PDF's in his second link. (I was looking for individual cartridge links.)Quote:
Originally Posted by Clint
I use a lot of range pickup brass mostly in .223/5.56. I started using a Hornady Comparator about 2 years ago. I have several rifles I reload for and I'm down to about 3 different length/sizes I resize for. That would be NATO chambers, Mini 14 chambers and bolt action chambers. The bolt action chambers are on .223's. They get resized down to 1.452 using the Hornady A330 bushing. The Mini 14's get resized to 1.455 using that same A330 Hornady bushing. The largest chambers are resized to 1.458 for the NATO ammo.
I'm flexible enough that I can live with +/- .002 for those sizes. There is some overlap so I have some versatility in using the different sizes of brass in different rifles. I just can't use the NATO brass in a .223 chamber. I spend a lot of time with the calipers measuring brass length to the shoulder and then storing it accordingly.
I also give away any brass any shorter than 1.755" long. I am finally retired after working for the last 55 years and I have time to spend on my reloading hobby. I have the time to chase those finer accuracy points. I also try to keep my case lengths within .005 of an inch in length. I prefer to use the longer cases with the shorter bullets in an effort to get close to the lands.
Yea, call me anal retentive but it beats watching the Voice and soap operas. I have the privilege of being just 6 miles away from a really nice 100 yard range so I get to test my "mistakes" almost daily.
kwg