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Posted: 2/14/2015 10:54:27 PM EDT
| This is my first build and I'm a little confused about checking headspace. I originally thought using the no go gauges from brownells was the way to go then I came across a couple threads about colt spec,military spec, field gauges...... Now I'm not sure what im supposed to do exactly. What are you do it yourselfs doing at home? If I should be using something other than the brownells gauges can someone pervide me with a link please. Thanks guys. |
| I knew it couldn't be checked but have read so many things about checking it to make sure the parts would be in spec. I got a spikes nib bcg and an arp barrel and I would hope they would match up with good headspace. I guess I don't have enough experience to make an educated dession on whether I should check it or not. Spoke to a guy at the local gun shop that said he has built 15 or so ar15's and never checked one. I've read other things saying its a must. If a gun is shot and the head space is out either on a new gun or one that is just wore out what are the symptoms? |
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I've been doing some more reading and I was hoping if someone could tell me if I understand this right. When you assemble a new gun you should use the sammi go nogo gauges to make sure the headspace is within safe operating range and then as the rifle starts to get some rounds through it, it should be checked periodically with the colt field gauge which will indicate if the rifle has more than the maximum headspace if the bolt will close on it.
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| Would someone just tell me what gauges to use to check min and max on a .223 Wilde chamber. My head is spinning trying to figure it out. I'm so confused with .223 vs 556 and commercial vs military gauges. I really wNt to get my gauges order to have them by next weekend and I'm just not sure on which ones. |
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Regardless of the chamber cut (.223 REM, 5.56 NATO, or .223 Wylde) they all measure headspace from the same reference points which is from the bolt-face to the .330 datum line. My opinion is to get a 1.4636" Go Gauge, and a 1.4666" No-Go Gauge to check a new barrel.
Go Gauge 1.4646" is the milspec for minimum headspace for a new barrel that's been high pressure tested (HPT) No-Go Gauge 1.4706" is the milspec for maximum headspace for a new barrel that's been high pressure tested (HPT) Go Gauge 1.4636" is the SAAMI spec for minimum headspace No-Go Gauge 1.4666" is the SAAMI spec for the longest a cartridge can be from the bolt-face to the .330 datum line. The milspec maximum headspace before a barrel's lifespan is used up is 1.4730" The SAAMI maximum headspace before a barrel's lifespan is used up is 1.4736" |
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Quoted: Head space is preset when the barrel manufacturer attached the barrel extension to the barrel. You can't adjust it. Unless you have a really old worn out barrel it's rare that there's a problem. There are those that say it should be checked anyway, YMMV. 1. Get a new bolt 2. Ream an unlined or stainless barrel 3. Send the out of spec barrel back for a new one that won't wear prematurely, because it was to tight. These are facts they have no emotion, anger, or arrogance attached to them. Sorry if it appears I am busting your chops wheel that is not intended. |
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Quoted:
Is there any reason a person could not remove the fireing pin and use a factory loaded round and see if it fully goes into battery for the minimum check. That's the same question I asked Dave Mason from Mason Reamers and he said there is too much variation between brands/styles of cartridges to make it an accurate check. |
| Remove your firing pin and put your bolt into battery, be prepared for your cam pin to rotate and give you much grief to get the bolt pulled back. I've done it with mixed results, it can be a real pain if it rotates good. So have a plan. Or simply file a firing pin short. |
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The difference between a NO GO and a FIELD gauge is very small. With a brand new barrel and bolt you don't want to be anywhere near EITHER the NO GO or FIELD dimension. If you can close a bolt on either one, it indicates that the combination of that bolt and that barrel has the MOST headspace allowable - essentially it says that the combination gauges as "worn out". You do NOT want a new barrel and bolt to start out as "worn out," do you?
I have Forster gauges for .223, and I use them on any new barrel/bolt combination (even if it's because I replaced a bolt). Actually my NO GO gauge is Forster's "Colt factory dimension" "Maximum" chamber gauge, which is ground for a headspace dimension of 1.4736", while their GO gauge is ground for 1.4636". Forster's NO GO gauge is ground for 1.4666". If the difference between "new" and "worn out" is only 3/1000", wouldn't it be a good idea not to start at the "worn out" end? |
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