Check AR Headspace?

[jcountry]

Here is an interesting idea: (Borrowed from another forum.)

In a prior topic, it was posted that building an AR without checking head-space was inviting disaster. I have heard the other side of the coin many times that it wasn't necessary because components are built to specifications with tight tolerances. I share the later view and have shot rifles (not ARs) with significant headspace issues which only resulted in split brass. Regardless of your view point, I thought of a way to check my new-build AR's headspace with no tools. When my BCG came in today, I took the BCG apart. I placed a new piece of brass with a flush primer installed into the chamber, and inserted the bolt (don't use a case loaded with powder and a bullet to do this - only a primer). That told me I had enough headspace especially since I could do it by hand. Then I used the firing pin to measure the freeplay/headspace tolerance of the chamber by sliding the firing pin into the back of the bolt and letting it touch the brass. The plunger forces the brass forward into the shoulder leaving any freeplay at the bolt's face. The difference between the firing pin flush with the bolt face and with the brass in the chamber is your freeplay. You can actually see the difference in the gap between the flat on the ring stop of the firing pin and the back of the bolt. If there is no gap, you have too much headspace.

I think this sounds interesting. Anyone tried something like this?

 

[Shovelhead]

Interesting, but have to agree if you have a headspace issue most likely something is out of spec. What would happen blown primers, case separation to name a couple. How's it fixed? Replace of offending part/s. Bolt..barrel... Probably best to change the cheapest first if you can't define a root cause of the headspace issue.

 

[GreenPanther]

B.A. CustomKydex should be along soon, he knows all about headspace.

 

[jcountry]

I do think headspace should be a non-issue on ARs. It is set at the factory by the barrel lug.

The military (and many civilians) change out bolts all day long-and never check headspace. I guess my point is that I kinda like this guy's quick, easy way to "check" it for confidence. But I also think checking headspace in an AR is un necessary. Anyone who thinks it is somehow critical-please tell me how to adjust it. Not possible.

I would imagine that the only thing a headspace check would tell you is whether you somehow have a badly bent barrel lug. What can be done about that? Not much-except a whole new barrel and lug, I reckon.

-Anyhow, I am obviously on the "don't worry about AR headspace" side of the fence-but I thought this guy's idea was pretty clever.

 

[Shovelhead]

B.A. Must be in a coma.... Come to think of it I've not seen his sweet face in a few days.. He's not wearing a pointed hat is he?

 

[Shovelhead]

OK someone do a search for B.A.customkydex besides me....

 

[Shovelhead]

I'm finding no post by B.A. However I'm finding post that he was quoted in but his original post is gone???? I'm looking for my tin foil cap.. Was there really a B.A. ? Or did he only exist in our minds? Did the banning hammer fall?

 

[HuckleberryFinn]

No need to check headspace. The barrel assuming torqued to proper spec 35-80ftlbs the standard bolt and standard reamed barrel will have the correct spacing. Just a waste of time IMO. If it's severely off the only 2 causes would be an out of spec bolt which means replace it or a out of spec barrel which means replace or have re-reamed. If you are having issues 9 out of 10 times it's cheaper to replace the parts then have to pay to get it reworked. It's a pain in the ass.

Now on the No-Go gauge if the gauge is for a 223 chamber, and your stuffing it down a 5.56 Nato chamber then half the time it will swallow it with forceful pressure against the bolt. Bottom line here is if the 5.56 Nato chamber/bolt will lock up on a 223 Go gauge, and have to be forced to lock up on a No-Go gauge, all is fine.
Note: To get the true reading you need to pull the extractor/ejector off the bolt, and then ride the bolt/carrier closed by hand Allowing the Bolt to snap/slam closed using the recoil spring is not the way to use the gauges. To sum it all up slightly longer head spacing (than 223) is ok in the auto loader it’s the short/rough head spaced chamber which the headaches begin.

- - - Updated - - -

No need to check headspace. The barrel assuming torqued to proper spec 35-80ftlbs the standard bolt and standard reamed barrel will have the correct spacing. Just a waste of time IMO. If it's severely off the only 2 causes would be an out of spec bolt which means replace it or a out of spec barrel which means replace or have re-reamed. If you are having issues 9 out of 10 times it's cheaper to replace the parts then have to pay to get it reworked. It's a pain in the ass.

Now on the No-Go gauge if the gauge is for a 223 chamber, and your stuffing it down a 5.56 Nato chamber then half the time it will swallow it with forceful pressure against the bolt. Bottom line here is if the 5.56 Nato chamber/bolt will lock up on a 223 Go gauge, and have to be forced to lock up on a No-Go gauge, all is fine.
Note: To get the true reading you need to pull the extractor/ejector off the bolt, and then ride the bolt/carrier closed by hand Allowing the Bolt to snap/slam closed using the recoil spring is not the way to use the gauges. To sum it all up slightly longer head spacing (than 223) is ok in the auto loader it’s the short/rough head spaced chamber which the headaches begin.

 

[jeffdt]

OK someone do a search for B.A.customkydex besides me....

BA is at the PRIDE celebration. He'll be back when he wakes up.

 

[Shovelhead]

BA is at the PRIDE celebration. He'll be back when he wakes up.

I'm worried about the little guy.