Headspace Issue?

[38 Special]

Hey folks,

I have an ak kit I bought and I was checking the headspace today. It has a new barrel on it that came with the kit and was supposed to be headspaced by them. This guy has a great reputation so maybe its right and I am overlooking something. I ordered a go and no-go gauge from Brownells. It will not shut on the go. It goes to about 8.5mm from shutting. It will close fine on a wolf and a golden tiger cartridge. It closes on a Tulammo but feels a bit tight? I have not removed the barrel so it is just like it was when I got it. I cleaned the bolt and chamber and trunnion area and everything really good. When I use just the bolt it comes really close to twisting all the way in. In fact I did twist it in one time with the bolt by itself but it was very tight and I felt like I was forcing it too much. Am I close enough or do I need to do something? What can I do? Am I overlooking something? This is my first build so I may be overlooking something.

Thanks for your help!

38 Special

[klewan]

8.5mm from closing????? You must have the wrong gauge.

You're supposed to exert 30 pounds of force on the bolt to check. Commies like their headspace pretty tight. AK Builder? Curtis has a good rep....

[Twinkies]

theres plenty to read about this over on AKfiles, but I try to set my headspace so that it's very close to closing on a GO gauge but not quite. The bolt will close on live rounds no prob... this is setting it on the "tight" side.
Sounds like yours is set perfect.
Not sure where your 8.5mm measurement comes into play?? What part of the bolt to trunnion clearance are we talking about here?

Just make sure when you press the barrel back in the trunnion that you check headspace again.

[38 Special]

The 8.5 mm is the distance from the bolt carrier and the front trunnion when trying to shut the bolt.

The barrel is in. I haven't taken it out.

I am using a 7.62 X 39 go guage.

Sounds like I may be fine.

I'll read up over on Ak files.

Tnx Gentleman!

[klewan]

Keep your face away from the gun when you fire it for the first time....hands too. Headspace is something 5% of the gunners understand.

[bohoki]

just take a case you fired out of an sks and put a piece of blue painters tape on the butt it should close on one layer maybe on 2 but not on 3

[kcstott]

The 8.5 mm is the distance from the bolt carrier and the front trunnion when trying to shut the bolt.

The barrel is in. I haven't taken it out.

I am using a 7.62 X 39 go guage.

Sounds like I may be fine.

I'll read up over on Ak files.

Tnx Gentleman!

Because i don't know what the distance is in relation to headspace I'll tell you this take your bolt out of the carrier and insert the gage and try to close. do you have about a 3mm gap between the upper lug and the rail?

If so you are good to go. that is about 15kg of force to close the bolt

[tujungatoes]

just take a case you fired out of an sks and put a piece of blue painters tape on the butt it should close on one layer maybe on 2 but not on 3

I thought you were smarter than that.

[klewan]

I thought you were smarter than that.

Don't get all smart *** on us. The tape works. It's only the peeps that think spending $60 on a gauge is the way to go. You shoot a cartridge, it doesn't pop the gun. It's a good one.

[kcstott]

Don't get all smart *** on us. The tape works. It's only the peeps that think spending $60 on a gauge is the way to go. You shoot a cartridge, it doesn't pop the gun. It's a good one.

Do we have to go over this again???

tape ain't good for even the zombie WTF ever you want to call it.


OK, One more time for the slow kids

The reason why using tape to head space a rifle is a bad idea is because you have no idea where your "factory" rounds land on the datum line. you know your headspace distance??



You see the gray line with the arrow head that's your headspace dimension.

Now using the 7.62x39mm and an example I measured a good number of cases on a toolmakers microscope accurate to within .0001" and I found all of the rounds i measured to be way undersize.

How far you ask?? How about .008" to .012" UNDER the factory minimum (CIP for those so inclined)

So tell me again how the hell tape works?? you add a layer and it adds so much to the headspace length and you check with another layer and the bolt won't close and you think you're good??

Where the hell did you start from? Too big or too small?? I ask because the last time I checked a box of ammo didn't have the headspace dimension on the box.

Tape can only be used as a "reference" on a GO gage as the gage has no body taper which is something you guys tend to forget about. so in a pinch off a known standard tape can be used on a go gage to reach no go length or on a no go to reach field length. But it needs to be stated that this is only marginally better then taping a case

Headspace is measured off the shoulder. and adding tape to the rear of a live or worse yet a fired case the body will bottom out before the shoulder will.

So I don't care if it worked for you, or some Gods gift to Gunsmiths said it was alright to do. It is inaccurate and dangerous.

You idiots will throw all kinds of money on the rarest East German, Yugo, Polish, Khyber pass but you won't pony up for the right tools??

Cheep tools to boot. and cheep insurance. The day that you have a case head separation you will never use tape again.

One more reason I do not go to public ranges, you never know who built the rifle being shot next to you.

[valley82]

Don't get all smart *** on us. The tape works. It's only the peeps that think spending $60 on a gauge is the way to go. You shoot a cartridge, it doesn't pop the gun. It's a good one.

Another reason not to go to public ranges added...
Only a cheap ***** would not properly check headspace to save a one time expense of $60.00
Why would you possibly build a rifle from a parts kit and not spend $60.00 for a no go guage? It is probably the cheapest tool in the lineup and the most critical...

[tujungatoes]

Don't get all smart *** on us. The tape works. It's only the peeps that think spending $60 on a gauge is the way to go. You shoot a cartridge, it doesn't pop the gun. It's a good one.

Kerry just explained why the tape method doesn't work. Let me take it a step further. Have you ever had a gun blow up in your face? I have...and I assure you that saying the experience was unpleasant is a serious f**king understatement. $60 for a couple gauges is cheap insurance when you have 45,000psi 12 inches from your face.

[ar15barrels]

I thought you were smarter than that.

Never doubt the incompetence of cheapskates...

[38 Special]

It checks fine now. I couldn't get the darn thing to rotate as it was closing and thought it was headspace. It was a rail issue. I don't have my rails welded in yet and they are just hanging onto some screws and nuts I stuck through where the center support goes. They got a little out of alignment and were catching and binding the bolt. (Rookie mistake. Yeah I need to weld them.) It closes fine now. I think I'm good. It doesn't close on the no go and closes fine on 3 different brands of ammo.

KCScott, I'll measure it tomorrow(or later today, depending on how you look at things) but that seems about where it was when I twisted it in by hand.

Thanks again for everyone's help.

[kcstott]

It checks fine now. I couldn't get the darn thing to rotate as it was closing and thought it was headspace. It was a rail issue. I don't have my rails welded in yet and they are just hanging onto some screws and nuts I stuck through where the center support goes. They got a little out of alignment and were catching and binding the bolt. (Rookie mistake. Yeah I need to weld them.) It closes fine now. I think I'm good. It doesn't close on the no go and closes fine on 3 different brands of ammo.

KCScott, I'll measure it tomorrow(or later today, depending on how you look at things) but that seems about where it was when I twisted it in by hand.

Thanks again for everyone's help.

In my experience 3mm before closing is a good snug headspace that falls right in there at the 15 Kg of force to get it to fully close and it is the top rail to lug.

That said even if it does close fully on a go gage but doesn't close on a no go you are good. Like stated above the they like the headspace tight