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View Full Version : 7.62 X 39 closed on a no-go


BB63Squid
02-24-2010, 10:44 PM
So I finally was able to source some go and no-go gauges.

I can get my bolt to close on the no-go with a little bit of force or if I let the bolt fly home. Now to extract it required a butt-stroke to free the bolt. These were SAAMI rate gauges and I don't have a Field gauge.

This was done on a 82 Romy-G with matching numbers kit.

Am I at the edge of tolerance or in the no-fly zone?

gunboat
02-24-2010, 11:30 PM
possibly -- but it is also possible you have dinged your chamber. Gauges are usually hardened steel. Your chamber is soft by comparison. Letting the bolt slam home possibly gives a false reading by driving the hard guage in too far. All said, likely your chamber is marginal. my ha-penny cva10airdale

Argonaut
02-24-2010, 11:38 PM
Sounds like it. Probably close enough to fire it and inspect the empty case with a micrometer.

ar15barrels
02-24-2010, 11:48 PM
I can get my bolt to close on the no-go with a little bit of force or if I let the bolt fly home.

First off, don't EVER EVER EVER force a bolt on a headspace gauge.
The worst thing you could ever do is to let the bolt fly home under spring tension.

ar15barrels
02-24-2010, 11:49 PM
Sounds like it. Probably close enough to fire it and inspect the empty case with a micrometer.

How exactly would you suggest measuring the empty case with a micrometer to determine headspace?

Ford8N
02-25-2010, 5:01 AM
That vintage Romy was during the time the Romanian regime fired all the craftsmen at the AK factory and replaced them with less experienced monkeys. That being said, try the no-go with two pieces of masking tape, it shouldn't close. If it does, time to start swapping bolts out to find one that will work. Or set back the barrel and re-drill the pin hole and drill shank it. It's an easy fix, after all, it's an AK.

uxo2
02-25-2010, 8:36 AM
I am speechless.........

I can get my bolt to close on the no-go with a little bit of force or if I let the bolt fly home. Now to extract it required a butt-stroke to free the bolt.

Now for the correct way to do it on a AK.
http://www.youtube.com/watch?v=8HR3RnBNVTA

ar15barrels
02-25-2010, 8:44 AM
I am speechless.........

I bet that he could get a field gauge to fit with a hammer. ;)

uxo2
02-25-2010, 8:54 AM
I bet that he could get a field gauge to fit with a hammer. ;)

You think afghan kids do it that way....

Do I use the granite or quartz rock to check headspace.




Live and learn....

I hope he test fires with a 30 foot string to pull on the trigger.

BB63Squid
02-25-2010, 9:02 AM
I am speechless.........

I can get my bolt to close on the no-go with a little bit of force or if I let the bolt fly home. Now to extract it required a butt-stroke to free the bolt.

Now for the correct way to do it on a AK.
http://www.youtube.com/watch?v=8HR3RnBNVTA

I'm glad I take your breath away.

BB63Squid
02-25-2010, 9:03 AM
I bet that he could get a field gauge to fit with a hammer. ;)

I bet I could too.

uxo2
02-25-2010, 9:28 AM
I bet I could too.

we all made mistakes..............

Hope it works out

MadRiverArms
02-25-2010, 9:51 AM
Strip the receiver of the fire control group and try a live round with just the bolt and see if there is play front to rear when it is rotated into the closed position. Then repeat with the bolt in the carrier, move the bolt carrier back and forth (not enough to make to bolt rotate) and observe the bolt to see if it is moving back and forth.

Closing on the no go (without force means that there is too much play and when the round fires the force will be transmitted into the trunnion with a hammer force instead of a smooth continuous pulse through the metal. It's a small movement but my opinion is that too much of it over a period of time will lead to problems. That being said it is not as dangerous as the bolt not closing on the go gauge.

-G

Neil McCauley
02-25-2010, 10:03 AM
Paging justin

MrNiceGuy
02-25-2010, 10:40 AM
I'd take the firing pin out if I was gonna play with a live round......just say'n......

adamsreeftank
02-25-2010, 12:35 PM
http://knowyourmeme.com/i/10960/original/Doitwrongsoccer.jpg?1251089201

BB63Squid
02-25-2010, 12:46 PM
Strip the receiver of the fire control group and try a live round with just the bolt and see if there is play front to rear when it is rotated into the closed position. Then repeat with the bolt in the carrier, move the bolt carrier back and forth (not enough to make to bolt rotate) and observe the bolt to see if it is moving back and forth.

Closing on the no go (without force means that there is too much play and when the round fires the force will be transmitted into the trunnion with a hammer force instead of a smooth continuous pulse through the metal. It's a small movement but my opinion is that too much of it over a period of time will lead to problems. That being said it is not as dangerous as the bolt not closing on the go gauge.

-G

I'd take the firing pin out if I was gonna play with a live round......just say'n......

Thanks for the technical advise. This was what I was lookin' for. Heading to Vegas in an hour so I will check when I get back.

BB63Squid
02-25-2010, 12:47 PM
That vintage Romy was during the time the Romanian regime fired all the craftsmen at the AK factory and replaced them with less experienced monkeys. That being said, try the no-go with two pieces of masking tape, it shouldn't close. If it does, time to start swapping bolts out to find one that will work. Or set back the barrel and re-drill the pin hole and drill shank it. It's an easy fix, after all, it's an AK.

Will try Gowking's method first, if it's bad I will obviously look down this path.

Thanks

ar15barrels
02-25-2010, 1:02 PM
Since you didn't read these the first time, how about reading them now...

http://www.forsterproducts.com/client_images/catalog19938/pages/files/Headspace_Gage_Instructions.pdf

Seesm
02-25-2010, 1:13 PM
Lucky the OP is mild mannered... You guys are tough sometimes... Enjoy Vegas!!

BB63Squid
02-25-2010, 1:23 PM
Since you didn't read these the first time, how about reading them now...

http://www.forsterproducts.com/client_images/catalog19938/pages/files/Headspace_Gage_Instructions.pdf

Thanks for the read.

Here is one for you Randall...

http://ebooksarchive.files.wordpress.com/2009/07/si-dchwfip.jpg

MadRiverArms
02-25-2010, 3:04 PM
I'd take the firing pin out if I was gonna play with a live round......just say'n......

With no hammer in place? Nothing in my description would cause the bolt to move forward with such force as to accidentally fire the round. Might as well give up before one accidentally sets off a box of cartridges, LOL.

-G

ar15barrels
02-25-2010, 3:25 PM
Here is one for you Randall...

http://ebooksarchive.files.wordpress.com/2009/07/si-dchwfip.jpg

I got enough friends.
I don't need to earn more.

uxo2
02-25-2010, 3:57 PM
head space gauges in hand but it looks like
their not going to be used?

Info on how to do it correctly ?

http://www.forsterproducts.com/client_images/catalog19938/pages/files/Headspace_Gage_Instructions.pdf

http://www.youtube.com/watch?v=8HR3RnBNVTA

Instead...some shady questionable method with possible ND
in the works.....

This is going to be interesting.......

MadRiverArms
02-25-2010, 6:30 PM
Shady? Are you serious? He has already tried the gauges and found that it is possible to close on the no-go with a little force. I'm not advocating his letting the bolt ride forward on the gauge either if that's what you think. that being said I see nothing wrong or inherently unsafe about chambering a round as long as it's done in a safe fashion. Lets see, no hammer, no trigger, no recoil spring. Just slow, smooth movements of the bolt and bolt/carrier to check for play? Yeah that's got shady and disaster written all over it pal.

-G

head space gauges in hand but it looks like
their not going to be used?

Info on how to do it correctly ?

http://www.forsterproducts.com/client_images/catalog19938/pages/files/Headspace_Gage_Instructions.pdf

http://www.youtube.com/watch?v=8HR3RnBNVTA

Instead...some shady questionable method with possible ND
in the works.....

This is going to be interesting.......

ar15barrels
02-25-2010, 7:57 PM
Shady? Are you serious? He has already tried the gauges and found that it is possible to close on the no-go with a little force.

Which just proves he did not read the directions.

Insert the proper gage into the action. Attempt to close the bolt on the gage.
CAUTION Never force the bolt closed on a gage. A rifle with correct headspace should close easily and without feel on the GO gage, but should not close on the FIELD gage. If it does close on the NO-GO gage, but not on the FIELD gage, the rifle may still be serviceable.

NO EMPHASIS ADDED.

BB63Squid
02-26-2010, 1:55 AM
Which just proves he did not read the directions.



NO EMPHASIS ADDED.

That has already been established. I DID NOT READ THOSE INSTRUCTIONS WTF IS YOUR POINT? Or are you just jacking up your post count?

mofugly13
02-26-2010, 6:25 AM
The point is that if you had read them, you would know that your chamber was good to go. Although at the border of excessive headspace, probably still within spec. But you went and FORCED THE BOLT CLOSED, even letting it slam home which is a NO-NO. If you had read the instructions you would know this. Headspace gages are precision ground, and you probably ruined your no-go gage. So now that we know that you screwed up, what is your question? Sounds like you need to try a field gage, or buy a new no-go gage and start over. You could probably send the damaged gage back to the manufacturer to see if it's still within spec.

paul0660
02-26-2010, 6:46 AM
I was speechless and got over it. It would have passed the no go test if not forced. It will most certainly pass the field test. I would shoot it with brass and look for case problems, and not expect to find any.


And IF there were no problems with the brass (stretching, cracking) go ahead and use combloc steel.

MadRiverArms
02-26-2010, 10:20 AM
As a side note you should be using CIP gauges which vary slightly from SAAMI.

-G

ar15barrels
02-26-2010, 10:22 AM
As a side note you should be using CIP gauges which vary slightly from SAAMI.

Do you have a reference on CIP gauge specs?

MadRiverArms
02-26-2010, 11:19 AM
My understanding is that CIP is based on Russian specifications. Manson makes HS gauges to SAAMI and CIP specifications for 7.62x39mm so the correct gauges are readily available for use with Eastern European manufactured firearms in 7.62x39.

A wiki on the Delta L Problem (difference between CIP and SAAMI specs:

http://en.wikipedia.org/wiki/Delta_L_problem

Some discussion on the specs:

http://www.akfiles.com/forums/showthread.php?t=40192

http://www.akfiles.com/forums/showthread.php?t=17887&highlight=SAAMI+CIP

As for the actual documentation for the CIP headspace gauge standard I couldn't readily find them listed on the official site:

http://www.cip-bp.org/


-G

woodey
02-26-2010, 11:42 AM
Darn Go, your like Mr.Wizzard of head spacing :p

My understanding is that CIP is based on Russian specifications. Manson makes HS gauges to SAAMI and CIP specifications for 7.62x39mm so the correct gauges are readily available for use with Eastern European manufactured firearms in 7.62x39.

A wiki on the Delta L Problem (difference between CIP and SAAMI specs:

http://en.wikipedia.org/wiki/Delta_L_problem

Some discussion on the specs:

http://www.akfiles.com/forums/showthread.php?t=40192

http://www.akfiles.com/forums/showthread.php?t=17887&highlight=SAAMI+CIP

As for the actual documentation for the CIP headspace gauge standard I couldn't readily find them listed on the official site:

http://www.cip-bp.org/


-G

ar15barrels
02-26-2010, 11:52 AM
That's crazy how CIP specs the headspace datum.

http://upload.wikimedia.org/wikipedia/commons/thumb/8/8e/.30-06_Springfield.svg/400px-.30-06_Springfield.svg.png

You can't reliably measure to that point on a gauge because that point is a sharp point that would be too weak to measure.

SAAMI does it better with the ring diameter reference as you can actually make a ring and measure to it's edge.

uxo2
02-26-2010, 7:51 PM
BB63squid...
thank you for sharing the ""How not to do a Head space check"
Because I thought this thread was going DOWN hill but some good info has come about.....

Noobert
02-26-2010, 8:33 PM
Wow, Randall got banned?

bigbob76
02-27-2010, 9:46 AM
This thread has been revealing. Personally, I would never use language or tone in a thread that I wouldn't use to a person's face. I was taught to treat everybody with respect whether I feel they've earned my respect or not. It seems to me that if the time for harsh words has come the time for talking has already passed.

gunboat
02-27-2010, 5:02 PM
A +10 to you Bob -- The net is great but the cloak of anonymity seems to bring out a rudeness in those who would not dare speak in that manner to your face.

ar15barrels
02-27-2010, 7:21 PM
The net is great but the cloak of anonymity seems to bring out a rudeness in those who would not dare speak in that manner to your face.

That's why my name is right in my signature.
I'm NOT anonymous.

gunboat
02-27-2010, 8:04 PM
If the shoe fits--

diginit
02-27-2010, 10:26 PM
That has already been established. I DID NOT READ THOSE INSTRUCTIONS WTF IS YOUR POINT? Or are you just jacking up your post count?

When all else fails... Read the directions...
I doubt that Randal is worried about his post count. He has always been very helpful and knows his sh*t. If you choose not to follow the instructions on ANY product, What do you expect? You may as well rebuild your engine and transmission with a hammer and nails.

diginit
02-27-2010, 10:48 PM
OK. Enough argument... Cool your jets guys...
Your bolt will not close on a No Go guage with matching nos? What does that tell you? The case head is too far from the chamber, Right? Does the bolt lock correctly with an empty chamber? Is it assembled correctly? Are you getting slamfires? Are you chambering ammo to match the chamber? 7.62x39 right? Did you just press in a US barrel or press in the original? How did the pin line up?
The more specifics, the better for people on the forum to help you. I'm sure we can figure it out.

Seesm
02-28-2010, 12:02 AM
Ok group hug now... OK GO!!

ar15barrels
02-28-2010, 12:11 AM
Closing on a no-go IS acceptable on a used gun.
The mere fact that he had to FORCE the bolt closed on the no-go tells us that it would NOT have closed on the no-go if checked correctly.
Go and no-go are only for new guns.
Once a gun is broken in, all you worry about is a field gauge fitting.
If the gun will close on a field, then you have a problem.
If it won't close on a field, it's good to go.

JeffM
02-28-2010, 12:43 AM
Everyone is an expert...

































































































































but some more than others

diginit
03-01-2010, 9:28 PM
Never said I was an expert. Got my gauges mixed up. But it stopped the fight right? You want to start another or what? If you want to be a jerk, I can too, But don't you think helping the OP would be a better idea? We are close enough to talk in person if you like. No hiding behind a monitor then...

Ford8N
03-02-2010, 4:48 AM
Closing on a no-go IS acceptable on a used gun.
The mere fact that he had to FORCE the bolt closed on the no-go tells us that it would NOT have closed on the no-go if checked correctly.
Go and no-go are only for new guns.
Once a gun is broken in, all you worry about is a field gauge fitting.
If the gun will close on a field, then you have a problem.
If it won't close on a field, it's good to go.

That's interesting, makes sense. That gauges are for new guns to set tolerances. Thanks for the tip.