Headspace checks

[Iraqgunz]

So much overthinking about something so simple.

[SiGfever]

So much overthinking about something so simple.

I know, my ignorance had me running around the rabbit hole. Lesson learned.

[Todd.K]

Forster and Clymer both list the numbers on them. Depending on how often they are used those markings wear off.

Good to hear more are being marked with the number. Here is what we can do with actual numbers.

SAAMI headspace for 223 REM is 1.4636 to 1.4736, but most guns are not made on/near the high limit. A commercial No-Go gauge is often only 1.4666, as they are mostly made for chambering bolt guns.

Military acceptance spec for a new M16/M4 rifle is 1.4646 to 1.4706

[mark5pt56]

Go to Office max, get a green, red and black paint pen and mark the gauges on a non wear/contact point. Of course green-go, red-no go and black for field(think black in Coopers color code)

[Eric D.]

From what I’ve seen go and no-go gage dimensions are arbitrary among different mfgs and thus pretty much worthless unless you’re a barrel maker.

1.4736” is the Field dimension and that’s what I use.

Whether or not these commercial gages are actually within the 0.0002” a lot of them claim is a whole other issue...

[sinister]

Forster article:

https://www.forsterproducts.com/pdf/brochures/nato1.pdf

...and another:

http://ar15barrels.com/data/headspace.pdf

For civilians and cheap bastards like me who actually reload spent cases for multiple rifles and carbines, I'd rather have minimal-sized cases for longevity and cross-platform compatibility. Individual military rifle and carbine cartridges just have to fire and function once -- and once safely fired that piece of brass is ejected overboard, of no use or care of the weapon firer.

[elephantrider]

From what I’ve seen go and no-go gage dimensions are arbitrary among different mfgs and thus pretty much worthless unless you’re a barrel maker.

1.4736” is the Field dimension and that’s what I use.

Whether or not these commercial gages are actually within the 0.0002” a lot of them claim is a whole other issue...

Where headspace gages are useful IMO, is when you can cross check them using a headspace comparator and calipers. Then you can see where your rifle headspace is in relation to your ammunition, and visa versa.

[Eric D.]

I follow you. I have the hornady comparator and use it for my reloading. The only issue I have with it is not knowing the exact diameter of the datum line where the bushings contact the case shoulder. That diameter is supposed to be 0.330” but all the bushings I’ve seen have a radiused or chamfered edge on the end of the bore and it’s obvious that the contacting datum diameter is not the 0.330” that it should be, even if only a few thou larger, so the bushing meets the case shoulder deeper than it should and it produces a false hs measurement. If I use the comparator to measure my field gage I get a value less than the 1.4736” the field gage should be. Now, if I assume the field gage is made to the specs it claims I could theoretically use it’s known size to “correct” or “calibrate” the hornady comparator which I know doesn’t produce correct absolute measurements, only relative ones.

Where headspace gages are useful IMO, is when you can cross check them using a headspace comparator and calipers. Then you can see where your rifle headspace is in relation to your ammunition, and visa versa.