Check headspace???

[lysander]

Something as new as Creedmoor would probably be okay.

Something like .300 Blackout, that doesn't have a SAAMI standard, no.

[Todd.K]

300 Blackout is SAAMI.

I don’t have any brand mixing concerns, but I do require the actual number on gauges.

[lysander]

300 Blackout is SAAMI.

I don’t have any brand mixing concerns, but I do require the actual number on gauges.

.300 Blackout does not have SAAMI approved headspace gauges, therefore there can be wide variation in GO, NOGO, and FIELD lengths.

Look it up.

[gunnerblue]

.300 Blackout does not have SAAMI approved headspace gauges, therefore there can be wide variation in GO, NOGO, and FIELD lengths.

Look it up.

PTG sells gauges made to the SAAMI specifications for 300 BLK

[gunnerblue]

5.56 and any .223 chamber all headspace the same. The difference is in the neck and throat, while headspace is where the shoulder is set.

300 BLK will need to use 300 BLK gauges.

I understand what you are saying, but to the uninitiated I think this is a little misleading. 5.56 and .223 chambers should be checked by their own respective gauges.

[Curlew]

.300 Blackout does not have SAAMI approved headspace gauges, therefore there can be wide variation in GO, NOGO, and FIELD lengths.

Look it up.

So does SAAMI actually approve headspace gauges for anything? When I tried looking it up, I found this FAQ:

https://saami.org/faqs/#1622648797091-fd1263a1-69ea

My read is that SAAMI defines min and max chamber lengths, but it’s up to the firearm manufacturer to decide where within that range they want their chambers to land, and to gauge accordingly. And the notion of a “field gauge” is explicitly not endorsed.

[lysander]

So does SAAMI actually approve headspace gauges for anything? When I tried looking it up, I found this FAQ:

https://saami.org/faqs/#1622648797091-fd1263a1-69ea

My read is that SAAMI defines min and max chamber lengths, but it’s up to the firearm manufacturer to decide where within that range they want their chambers to land, and to gauge accordingly. And the notion of a “field gauge” is explicitly not endorsed.

Look up the 2015 (or later) editions of the SAAMI Z299 Series, Voluntary Industry Performance Standards for Pressure and Velocity

Z299.1 - Rimfire
Z299.2 - Shotshell
Z299.3 - Centerfire Pistol and Revolver
Z299.4 - Centerfire Rifle

Headspace gauge data starts on page

Z299.1 - 70 (77 in .pdf)
Z299.2 - 101 (108)
Z299.3 - 122 (131)
Z299.4 - 212 (224)

[lysander]

PTG sells gauges made to the SAAMI specifications for 300 BLK

Just like "mil-spec" . . . . meaningless marketing.

SAAMI does not have a specification for a .300 Blackout headspace gauge, they only specify the chamber dimensions. This is why multiple manufacturer's could have multiple gauges with slight differences, such as tolerancing, finish, material, hardness, etc . . .

[lysander]

AND, there is no such thing as a 5.56mm NATO headspace gauge.

There are M16 gauges

There are M249 gauges

There are M27 gauges

etc.

[Todd.K]

.300 Blackout does not have SAAMI approved headspace gauges, therefore there can be wide variation in GO, NOGO, and FIELD lengths.

Wide? Go and No-Go have to be within the 0.010” chamber depth tolerance of SAAMI or they are not 300BLK gauges.

Insist on gauges with the actual headspace number, so you will know how much less than maximum the No-Go (likely) is.

Field gauges are a relic of the past like proof load testing, when poor designs, questionable material and hardening processes were the norm.