I checked the headspace on a rifle I am assembling with Young Manufacturing National Match chrome bolt and Krieger barrel. I can only get about half lock-up with the GO gauge. This is with moderate pressure with one finger pressing on the bolt end. If I press pretty firmly with two fingers, it will achieve lockup, but it IS tight. Is this OK?
The barrel is a .223 Remington, not 5.56. I am using Forster gauges for .223 (they are marked .223). The GO gauge is 1.4636". I cleaned the chamber, the gauge, and the bolt face before use. The ejector has been removed from the bolt. My method was to let the extractor hold the gauge in place and then slide the bolt forward to lock up. The firing pin is still in.
I know the bolt chrome plating adds thickness, but Young told me the plating is .0002" thick, emphasizing that it is NOT .002". Krieger said their chambers are not so tight where that would cause any problem.
The extractor should not affect measurement and is not called out as a required step in several instructions I have seen. Can you tell me how the extractor could affect measurement?
My initial reluctance to pull the extractor was simply because I never did it before and did not what it required. I looked and very simple, so tried your advice with no extractor (or ejector). Guess what? It works! Closes on the GO gauge with no real resistance, and absolutely will not close on the NO-GO. Excellent! The extractor certainly DOES make a difference.
Thank you sir, for that advice. I can fire the first shot with confidence.
Just out of curiousity why would you hesitate to remove the extractor when there are no toolsrequired, but you removed the ejector which requires a tool as well as replacing the old roll pin. Am I confused?
I have checked the headspace many times over on carbines with the Bushmaster 5.56 gage and never needed to remove anything.
I did not hesitate to remove the extractor initially. I did not remove it because in the Brownells video I was watching, the extractor was shown as being left in. After comments here, I decided to remove the ejector again and the extractor, which was simple to remove. My main issue was removing the ejector several times. I did not want the roll pin to start to get loose. I had a spare, but it turns out it was .05" shorter and was not sure that was OK. I reused the original pin, and it appears to still be tight.
OK. I ordered a spare from Sinclairs and it is .39" long, while the original from the Young Manufacturing bolt is .44" long. Do you think the shorter roll pin is OK to use? If not, who is a good supplier of such parts?
This reminds me of the guy that was worried about the headspacing on his BCM upper and asked for help, then promptly ignored all advice given. Then he wasted time and money shipping the upper back to Paul who showed that it did not in fact close on a field gauge. He could have been shooting instead of spending 2 weeks or so with all his hand wringing. Hasn’t gotm4 and IG given you advice on checking headspace before?
The problem has been conflicting info, hence the questions. I found a source that says remove the ejector and leave in the extractor, and vice versa (here). I removed everything and it worked. It may have very well have worked with only the extractor removed, and next time will try that. Certainly easier than removing the ejector, although the tool makes this pretty much a non-event.
Not sure where the “conflicting” info is coming from, but some of us here have already offered the correct advice. If you use a Bushmaster 5.56 Field Gage (scroll about 1/4 way down) http://www.bushmaster.com/products.asp?cat=15 you will see the gage. I used it for several months and never had to remove the ejector. The extractor could be removed it you were concerned about damaging the rim. With a MILSPEC gage from Bill Ricca it is a simple drop in and check.
As for the roll pin Brownells sells them. It is a good idea to keep some spare parts on hand so just find a few more things you need and place the order, or don’t.
All here were on the same page, but a Brownells video for instance (and others) said to remove the ejector but leave the extractor in, just the opposite of what was recommended here.
Another forum thread on the topic of forums found general agreement that m4.carbine.net was probably the best of the forums for AR type rifles. That is why I joined.
Your assumption is correct. The barrel is chambered on the tight side of 223 Remington SAAMI specs. This is why I searched out and borrowed 223 Remington headspace gauges. I don’t know that 5.56 are different, but one or more of the gauges may be.
