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Posted: 2/9/2010 12:07:15 PM EDT
| First off I would like to start this topic off by letting everyone know I am a newb to the AR world and appreciate all of your comments in advance. My question is about checking headspace. I just bought a Young Manufacturing National Match Bolt Assembly and I am currently looking into barrels. I am thinking about a Sabre Defense, White Oak Arm., or Centurion Arms...maybe a Daniel Defense. Anyway I would like to know if it is completely necessary to buy a Go and No Go Gauge to check the headspace between your bolt and barrel. I hate to spend 40 to 50 bucks on two gauges I am only going to use once per build. Please let me know if you checked the headspace on your builds(especially if you are using any of the gear I am). Also I would like to know if anyone has experience with those barrels and how they feel about them. THANKS A MILLION! |
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The only gage you really need is the FIELD. A used rifle can close on a NO-GO and be perfectly safe as long as it rejects the FIELD gage. I check my rifles yearly with a FIELD gage to make sure headspace hasn't gone out of spec. It's overkill, but I like being able to see and stuff.
The TM says to check headspace after changing a barrel or bolt, not that most barrels and bolts are in spec so don't bother. Make sure you use a gage that matches the chamber in your rifle. a gage for 5.56 can give false readings in a .223 Rem. chamber and vice versa. Ask around in your hometown forum. I bet someone close to you has a FIELD gage you can use w/o having to buy it. BSW |
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Make sure you use a gage that matches the chamber in your rifle. a gage for 5.56 can give false readings in a .223 Rem. chamber and vice versa. I made this mistake. When looking for a Field headspace gage, I saw that many of the sites list their headspace gages as being 5.56/.223, or said 5.56 but showed a picture of a gage with .223 etched on it. So I incorrectly assumed they were compatible. However, I went directly to Forster's site because something told me I was mistaken. They specifically say the two are not compatible. They sell specific 5.56 NATO Headspace gages. I bought one of their maximum gages, which corresponds to the Field gage. In case anyone is interested, here's the link: Forster 5.56 NATO Headspace Gages |
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Not to derail the topic, but can someone explain what headspace is and how it is checked. Check out this sticky thread from the Build It Yourself forum: Headspace, Torque values, and Barrel Break-In |
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Not to derail the topic, but can someone explain what headspace is and how it is checked. Check out this sticky thread from the Build It Yourself forum: Headspace, Torque values, and Barrel Break-In Thank you, sir! |
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I got mine from Bill: http://www.billricca.com/collectors_corner.htm
About a 1/3 of the way down the page, look for 'M16 Maximum Headspace Gage, Ordnance Part Number 7799734, NSN 4933-00-070-7814. Disassembly of bolt not needed, gage is cut for extractor and ejector clearance. Each gage is new, in US GI pack' BSW |
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If Bill Ricca is out of stock, here is the next best thing.
http://www.brownells.com/.aspx/pid=6646/Product/5_56mm___223__HEADSPACE_GAUGE ALWAYS check headspace on a new build. More than one barrel has left a manufacturer not fully chamber finished reamed. Not checking and attempting to fire the rifle can lead to disaster. |
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If Bill Ricca is out of stock, here is the next best thing. http://www.brownells.com/.aspx/pid=6646/Product/5_56mm___223__HEADSPACE_GAUGE ALWAYS check headspace on a new build. More than one barrel has left a manufacturer not fully chamber finished reamed. Not checking and attempting to fire the rifle can lead to disaster. I have a Noveske recon and a young's NM. I still would need to check it on a new build? btw everyone thanks for the advice |
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If Bill Ricca is out of stock, here is the next best thing. http://www.brownells.com/.aspx/pid=6646/Product/5_56mm___223__HEADSPACE_GAUGE ALWAYS check headspace on a new build. More than one barrel has left a manufacturer not fully chamber finished reamed. Not checking and attempting to fire the rifle can lead to disaster. I have a Noveske recon and a young's NM. I still would need to check it on a new build? btw everyone thanks for the advice They are your eyes. How much are they worth? BSW |
| Somewhere around 8 uppers built, didn't check headspace on them and they shot perfectly. 2 or 3 more were headspaced by a local 'smith who offered the service for free and they all headspaced fine. AR headspace is set at the factory. If you buy good quality,new parts you shouldn't have an issue. |
I see a lot of people saying here headspace from the factory should be no problem. I don't want to be the guy to rain on some people's parade, but about 5% of the new uppers we get for work from bushmaster are no-go. Their response to "were these head-spaced?": "Well we test fire them, so there isn't an issue." 
We just bought a dozen LMT uppers and one was a no-go on the headspace, even though it came with the tag saying it was checked at the factory. We haven't had time to call them up, so I don't know how they'll respond, but it can't be worse than Bushmaster's. I'm never going to buy/build an AR without headspacing them before I shoot. I know they'll work fine on "field-guage" but a brand new rifle and bolt should be frigging 100% good to go. If they require the field gauge it should be because I shot them. I'd get a set, it's cheap insurance for reliability and accuracy, especially if you're putting a good amount of cash into a high quality bbl. |
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It seems to me only three things can happen concerning headspace. One, the bolt won't close. In this case you know it's incorrect. Two, the bolt closes, but the chamber is too long. A quick look at the first fired case, and you see it's been fire formed. You now know the chamber is too long. Three,the chambers correct. I would be MUCH more concerned with the bore diameter of the barrel. If it's too small, you may blow the rifle up.
Noob |
| TCBA_Joe - good info my man!!! thanks guys. I diffenently will check this out see how I will have well over 2k in this after it is all said and done with. However, I do think like you guys and it should be only an issue for guns that are shot..oh well better safe then sorry |
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I see a lot of people saying here headspace from the factory should be no problem. I don't want to be the guy to rain on some people's parade, but about 5% of the new uppers we get for work from bushmaster are no-go. Their response to "were these head-spaced?": "Well we test fire them, so there isn't an issue."
We just bought a dozen LMT uppers and one was a no-go on the headspace, even though it came with the tag saying it was checked at the factory. We haven't had time to call them up, so I don't know how they'll respond, but it can't be worse than Bushmaster's. I'm never going to buy/build an AR without headspacing them before I shoot. I know they'll work fine on "field-guage" but a brand new rifle and bolt should be frigging 100% good to go. If they require the field gauge it should be because I shot them. I'd get a set, it's cheap insurance for reliability and accuracy, especially if you're putting a good amount of cash into a high quality bbl. Closing on a no-go gage doesnt mean a thing. Get yourself a field gage and toss that no-go gage, it is causing you to worry about problems that you dont have. |
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WE'VE BEEN BUILDING CUSTOM AR' UPPERS FOR QUITE SOME TIME. WE'VE USED THE FOLLOWING BARRELS IN THESE BUILDS:
COLT LMT KRIEGER, BY COMPASS LAKE ENGINEERING DOUGLAS, BY COMPASS LAKE ENGINEERING LILJA, BY COMPASS LAKE ENGINEERING NOVESKE S/S NOVESKE N4 OUR PREFERRED BOLTS ARE THE PROOF-ROUND TESTED, MP-INSPECTED VARIETY FROM LMT. WE TRY TO KEEP QUITE A FEW ON HAND. THEIR TOLERANCES ARE QUITE GOOD, SPANNING A MAX RANGE OF 0.004", WITH 90+% OF THEM WITHIN 0.003" AND 70% WITHIN 0.002". WE HAVE TWO COMPLETE SET OF PACIFIC TOOL AND GUAGE HEADSPACE GAUGES FROM 1.4626" TO 1.4716" IN INCREMENTS OF 0.001". THIS MAKES PRECISE FITTING OF A BOLT TO A BARREL FOR A GIVEN APPLICATION POSSIBLE. (BUT TEDIOUS!) WE TYPICALLY SET UP A GENERAL USE GUN WITH A HEADSPACE OF 1.4666". I MIGHT GO LOOSER ON A GUN I KNOW IS GOING TO BE RUN HARD ON GENERIC BALL AMMO, SAY LIKE A 10.5" N4 GOING TO A SWAT TEAM MEMBER OR CIVILIAN HEADED FOR A 5-DAY TRAINING CLASS. PRECISION RIGS I LIKE TO RUN A TAD ON THE TIGHT SIDE IF I KNOW MATCH GRADE AMMO WILL ONLY BE USED. COMPASS LAKE MATCH CHAMBERS RUN TIGHT. I HAVE RUN INTO SOME THAT WOULD BE COMPATIBLE WITH EACH AND EVERY BOLT I HAD. SO, THESE GOT LMT BOLTS FROM ONE END OF THE SPECTRUM IN ORDER TO MEET MINIMUM CHAMBER DIMENSIONS. NOVESKE SPEARS ALL OF HIS CHAMBERS AT 1.4666" BY DESIGN. FOR A PRECISION BUILD FOR USE WITH MATCH GRADE AMMO AND ONE OF HIS S/S BARRELS, I'LL LOOK FOR A BOLT THAT WILL CLOSE AT 1.4646" - 1.4656". DOES THESE THEORIES WORK? BASED ON RESULTS, I LIKE TO THINK SO. CAN I PROVE IT SCIENTIFICALLY? OF COURSE NOT. GOOD SHOOTING, WES |
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