headspacing, go or no go...

[mggunner34]

I got a couple of mg34 barrels at the sar show, to check the headspace on these do I need both a go and no go? or do I just put a go gauge in and make sure the bolt roller locks behind the bolt stop arm?

[haak48]

Many MG34 bolt/barrel combinations will accept even the NoGo gauge, and are still serviceable. If a field gauge locks into battery however, the combination is to large. All three gauges are useful in this regard. A badly worn bolt stop can increase head space greatly. Be sure to keep modern lubricants such as Break Free, etc. off ammunition because a cartridge that can not "grab" the chamber walls sufficiently will allow the bolt roller to batter the bolt stop and open up the head space. JH

[mggunner34]

insightful as always jim, thanks for the info, so in short I'll need all three gauges, go, no go and field? or just a no go and a field?

[JBaum]

3 gauges give you more information than 2.

[Gulfstream4]

The advatage to having all three guages is when the no-go guage fails but passes with the field guage you know that you are getting to a critical point of failure. This will require careful monitoring. As long as the field guage continues to pass you are good to go.

[mggunner34]

so with this platform is it the headspacing what determines whether a barrel and bolt combination will work properly? Or does headspacing determine if the barrel is safe to attempt to try the bolt and barrel combination?

[haak48]

so with this platform is it the head spacing what determines whether a barrel and bolt combination will work properly? Or does head spacing determine if the barrel is safe to attempt to try the bolt and barrel combination?

Both. But the main concern for shooters is safety. To much head space can allow the cartridge to back out of the barrel far enough that the case web can lose support and a head failure might occur. The gauges will allow you to make sure the dimensions are within a certain standard. Overall functioning of your MG34 is a combination of many parts working in harmony, proper head spacing is just one of those factors. JH