Gunsmithing AR15 Headspace

[EddieNFL]

How many agree with this guy?

Why do so many people insist on using a head space gauge for an AR15, and spending $400 on tools? - Yahoo Answers

Why do so many people insist on using a head space gauge for an AR15, and spending $400 on tools?
I build ARs as part of my job at a local gun store where I work full time.... And I'm not sure what I'm doing wrong, but I've never needed all that stuff.

When it comes to checking headspace.... Why? Has anyone ever found new AR parts that didn't headspace correctly?

A stock AR15 with it's 2MOA group is fine for me, as it is for most people. Additional precision works against reliability.

I just want to know which shop to avoid.

 

[Brian]

Can't get your link to work..

 

[Bradu]

I couldn't get the link to work either. It's obvious that guy has no clue what he's talking about just by what you copy and pasted.

 

[bptactical]

Yup, dead link.

His work should be easy to spot, channellock marks on the barrel nut, broken trigger guard ears, punch marks on the castle nut, hammer tracks on the lower where he missed the nail set driving the bolt catch pin etc.
2 M.O.A? Proud accomplishment to be sure.

 

[ORD]

Reasons that your average "local gun shop/store" should NOT engage in ANY "gunsmithing" services except for perhaps the rare mounting of a scope and boresighting, but even that seems to be a real stretch lately in terms of getting @#$% done right. Hell, I was in a local shop recently just before deer/gun season started and when the owner was asked if he'd boresighted a scope he mounted for a customer, his response was, "Um...well...I think I did but I don't keep any paperwork on those sorts of services since you can clearly tell the scope has been mounted so I honestly am not sure if I did it or not. Just shoot it and if its not on target, you can bring it back and I'll have a look." Stupid is as stupid does!!

Look...in assembling any AR platform rifle, you are working with stacking tolerances. As such, any time that you assemble a rifle with a barrel from mfg x and a bolt from mfg y that hasn't been specifically headspaced/fitted to the barrel in question when the barrel was being setup, you can and will sometimes run into problems with proper headspacing. All it takes is for one component to be out of spec or for two components to be well out on the edge of acceptable to cause issues. I've had it happen a handful of times over the years and while a trivial amount in the grand scheme of things, I'd personally rather take the ~10-15min it takes to check my own work (as well as that of others) and ensure that the headspacing is within the acceptable range. In fact, the only time I have ever even thought about NOT checking it is when I send my bolt off to a known/trusted gunsmith for him to use in setting up the AR barrel in question so that I KNOW it is right from the get go. Any time I buy/assemble or assemble for someone else any random selection of AR components, I check the headspace without exception. Its too simple a task to perform in a short amount of time to run the risk of possibly having the rifle go south on you in a hurry if something is awry.

Also, as to the LGS in question...there is so much wrong with the "2MOA group is fine for me" and "[a]dditional precision works against reliability" crap that guy is spewing that I scarcely know where to begin. Headspace isn't just a function of "precision" versus "imprecision" or "reliable" versus "unreliable." Its a matter of safe operation of the rifle. By assembling ARs as a business, and at the same time utterly failing to perform any degree of function/safety checking on the headspacing of said rifle, the idiot owner/employees are opening up a can of liability worms that they'll eventually choke on. If it were me, I wouldn't give that shop my money or my time if it was the last in town.

 

[EddieNFL]

Link should work now.

 

[rjacobs]

I have a field gauge for checking new builds. From what I read the go/no-go gauges arent really that useful for checking a pre-assembled barrel/receiver extension(which is the only stuff I buy, I dont install barrel extensions), but are really more for checking the installation of the barrel extension by the manufacturer. Am I right in my thought process here or should I also have a set of go/no go gauges for final checking an assembled upper?

 

[bptactical]

I have a field gauge for checking new builds. From what I read the go/no-go gauges arent really that useful for checking a pre-assembled barrel/receiver extension(which is the only stuff I buy, I dont install barrel extensions), but are really more for checking the installation of the barrel extension by the manufacturer. Am I right in my thought process here or should I also have a set of go/no go gauges for final checking an assembled upper?

A field gauge is not a good means of checking final head space. It only signifies when head space is so excessive the rifle is unsafe to fire.
Close on a go, no close on a no go.
Invest in the gauges.



I really enjoyed this line in the Yahoo (seems appropriate) : "You could even go cheaper and get a block of wood that fits the mag well, and clamp the wood in a vice... "

Too bad it's four years old, we could have some fun.

 

[Thumper580]

I'm not supporting what was in the first post but I do know a very competent local AR shop who has checked boatloads of AR builds and not had an out of spec head space check.... Always good to check but more the exception to be out of spec.

 

[rjacobs]

A field gauge is not a good means of checking final head space. It only signifies when head space is so excessive the rifle is unsafe to fire.
Close on a go, no close on a no go.
Invest in the gauges.

Roger that. They arent expensive. Im just really getting going building uppers in any quantity so I am still gathering all the proper tools to do it right as I have fixed multiple uppers that were NOT built right(not from a headspace perspective, but other issue's). I read a ton on what gauges were good to have and most of the guys I read where saying that basically just the field was the best to have.