Headspacing a new AR build

Pr589

Pr589

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So how many of you experienced AR builders check headspace before firing a new build.

I'm an AR noob and coming from platforms that require fitting and headspace checking. I'm using pretty good parts including a Rainier Ultramatch barrel in 223 Wylde and teaming this with a Daniel Defense bolt so tolerances should be fine but I'd prefer to avoid an unhappy surprise.

So do I invest in go and field gauges?
 
I guess I gamble on my build but it would be safer to use a headspace go/no-go gauge kit.

If your BCG and barrel are from a reputable manufacturer and the barrel already has a barrel extension, it'll be fairly safe to assume that you're good to go if all the system checks pass with flying colours after finishing the build. That's not to say that those manufacturers never churned out a lemon.
 
Always good to have a set of gauges. I would check any parts you mix from different manufacturers. If you build a BCM barreled upper with a BCM BCG, or DD barrel with a DD BCG, I wouldnt worry, but always good to check other builds.
 
If you use quality parts, head spacing is not required when assembling an AR15. The barrel extention and bolt are machined to very accurate tolerances. If it is out, you can't adjust anything, it means that either the barrel extention or the bolt is out of spec and needs to be replaced. This is something that very seldom happens fortunately.
 
RifleDude said:
If you use quality parts, head spacing is not required when assembling an AR15. The barrel extention and bolt are machined to very accurate tolerances. If it is out, you can't adjust anything, it means that either the barrel extention or the bolt is out of spec and needs to be replaced. This is something that very seldom happens fortunately.
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You're right, and I agree with you about quality parts being within spec right from factory...but when you say, "If it is out....", How will you determine that headspace is not to spec if you don't take that measurement? Do you take the chance and let something happen, and then determine that headspace was out of spec? For what it costs to buy these gauges and for how little effort it takes to measure headspace, it's a very wise decision, in my opinion, to give yourself the green light with this final check once you complete your build. You'll never know for sure unless you check.
 
Thanks for the feedback guys. Seems like some check, and some don't. Probability of failure is low but not zero.

I guess this is one of those personal risk decisions. I think I'll check if anyone at the club has a set of gauges before I decide. I have too many pieces of equipment I use infrequently to want to add one more piece of clutter to the shop.
 
The headspace is set when the barrel extension is installed. Not many companies make both their own barrels or bolts, so everything you get is a mixmaster for the most part right from the factory, regardless of who's name is on it.
I built 4 with no headspace gauges, measured fired brass was 2-3 thou over saami min spec on all of them...it's Lego for chrissake lol
 
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