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1/27/2015 9:42:29 PM EDT
Evening Everyone, I am a newbie to this forum and the firearms world (only a few years firearms experience) and have a question about my first AR build. I chose a 7.62x39 caliber and I am having problems with the headspace check. I am running a Yankee Hill 16in chrome lined barrel with a tactical ambush upper and bolt/BCG. The headspace go/no go gauges I bought from Midway both fully close the bolt into battery. I am in search of a field gauge to fully confirm proper headspacing. Is it possible that the bolt/barrel are not matching correctly? I installed a UTG free float rail and torqued the barrel nut to their specs. The barrel appeared to seat properly and I did not notice any issues with the upper receiver. I have read a lot on headspacing and have found its about 50/50 on people saying to check it and not check it. Just looking for some advice before I try to go to a gunsmith.
1/27/2015 10:17:01 PM EDT
[#1]
Quoted:
Evening Everyone, I am a newbie to this forum and the firearms world (only a few years firearms experience) and have a question about my first AR build. I chose a 7.62x39 caliber and I am having problems with the headspace check. I am running a Yankee Hill 16in chrome lined barrel with a tactical ambush upper and bolt/BCG. The headspace go/no go gauges I bought from Midway both fully close the bolt into battery. I am in search of a field gauge to fully confirm proper headspacing. Is it possible that the bolt/barrel are not matching correctly? I installed a UTG free float rail and torqued the barrel nut to their specs. The barrel appeared to seat properly and I did not notice any issues with the upper receiver. I have read a lot on headspacing and have found its about 50/50 on people saying to check it and not check it. Just looking for some advice before I try to go to a gunsmith.
View Quote




did you remove the extractor before using them?
1/27/2015 10:36:16 PM EDT
[#2]
Quote History
Quoted:




did you remove the extractor before using them?
View Quote View All Quotes
View All Quotes
Quote History
Quoted:
Quoted:
Evening Everyone, I am a newbie to this forum and the firearms world (only a few years firearms experience) and have a question about my first AR build. I chose a 7.62x39 caliber and I am having problems with the headspace check. I am running a Yankee Hill 16in chrome lined barrel with a tactical ambush upper and bolt/BCG. The headspace go/no go gauges I bought from Midway both fully close the bolt into battery. I am in search of a field gauge to fully confirm proper headspacing. Is it possible that the bolt/barrel are not matching correctly? I installed a UTG free float rail and torqued the barrel nut to their specs. The barrel appeared to seat properly and I did not notice any issues with the upper receiver. I have read a lot on headspacing and have found its about 50/50 on people saying to check it and not check it. Just looking for some advice before I try to go to a gunsmith.




did you remove the extractor before using them?


Extractor as well as ejector need removed, but those usually prevent the bolt from closing. This sounds like excessive headspace.
1/27/2015 10:39:52 PM EDT
[#3]
Yes. Disassembled the bolt and placed it back in the BCG as instructed. The one thing I have not been able to find is ant technical specs on the gauges. With this being my first run at this I am simply following directions/instructions. Are the gauges supposed to be identical is size and shape?  I would think one would be bugger than the other since the go gauge is minimal distance and the no go is max distance to the datum line. Am I wrong on this?
1/27/2015 10:41:18 PM EDT
[#4]
Quote History
Quoted:
Yes. Disassembled the bolt and placed it back in the BCG as instructed. The one thing I have not been able to find is ant technical specs on the gauges. With this being my first run at this I am simply following directions/instructions. Are the gauges supposed to be identical is size and shape?  I would think one would be bugger than the other since the go gauge is minimal distance and the no go is max distance to the datum line. Am I wrong on this?
View Quote



I have a set I can check the sizes
but I would assume its different lengths but barely any difference
1/27/2015 10:47:48 PM EDT
[#5]
I think the no go checked out 1/2 mm shorter
I dont remember now I had to go find another set of calipers and got them mixed up

but one was definitely shorter, but by a hair

I dont think you can tell by eye you will need to measure
1/27/2015 11:38:39 PM EDT
[#6]
http://saami.org/specifications_and_information/publications/download/206.pdf

See page 31 for the chamber dimensions.
1/28/2015 5:28:44 PM EDT
[#7]
I am waiting to hear back from Yankee Hill but does anyone know of the top of their head what specs they do their barrels to?
2/9/2015 5:55:59 PM EDT
[#8]
Finally called Yankee Hill and they were no help. They did say they headspace check their barrels prior to shipping but could not tell me if the barrel was made to SAAMI specs. Should I trust them?
2/10/2015 5:55:36 AM EDT
[#9]
So, have you shot it yet or just being overly cautious? I put one together a few month back, checked function with a dummy round (loaded & unloaded fine). I single loaded the first 5 rounds, "just in case" - I laid a 2x2 carpet square over the receiver & let her rip. Now has 100+ rounds (all steel) through it with no problem. Make sure you use full power hammer springs or your likely to get light primer strikes.
2/10/2015 5:03:47 PM EDT
[#10]
I would be more suspect of the bolt. See if you can find someone who owns a 7.62x39 AR and try with their bolt.
2/10/2015 6:09:21 PM EDT
[#11]
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