headspacing

Just reading up on building AK's. If you build one and the headspacing isn't correct, what has to be done to fix it?

You can drill the barrel retaining pin hole oversized after setting the headspace and use an oversized barrel pin.

silver - if hs does not check -yes you'd be looking at re-drilling for an oversize pin. this is what i am posting about as i type. lol.

i do know this much: we will have to push the bbl in slightly-then check with the go and no go gauges. fyi - i have 2 pacific tool and gauge brand CIP/euro spec gauges for 7.62x39 type cartridge( GO & NO GO).note: these where custom ordered at pacific tool & gauge outa white city, oregon.

what i am going to do is push in the bbl til it checks with the go gauge(bolt should luck up fully or close). on the NO GO bolt should NOT lock-up fully. so we're going to have to adjust til-both these tests check as told.

now here's where i'm lost. what size drill bit do i need and what size pin? atleast i got you half way there. lol

Enjoy: http://www.victorinc.com/Drill%20&%20Pin%20Chart.html

Larry

If head space is tight(won't close on a go gauge or a round) you can lightly file the locking ears of the bolt to get the desired fit.Go slow and test frequently.If its loose than your gonna have to move the barrel and get a bigger pin.

If head space is tight(won't close on a go gauge or a round) you can lightly file the locking ears of the bolt to get the desired fit.Go slow and test frequently.If its loose than your gonna have to move the barrel and get a bigger pin.

This is probably not the recommended method, since it's easy to file one locking ear more than the other and end up with one ear carrying the whole load . . .

But as always, YMMV . . .

Larry

[QUOTE]This is probably not the recommended method, since it's easy to file one locking ear more than the other and end up with one ear carrying the whole load . . .



Use a "sharpie' marker (color the contact areas of the bolt,put your go gauge in and move the bolt carrier.Points of contact will be wiped clean.File these areas lightly and recheck )

This method has worked many times for me.All my guns are shooters.They all get shot on a regular basis.When I first got into the hobby I wanted only "matching" kits for fear of headspace issues but now I tackle any.Moving the barrel is only required for headspace that is loose in my book. I'm just a Home Builder I don't have a complete metal working shop at my disposal.

[QUOTE]This is probably not the recommended method, since it's easy to file one locking ear more than the other and end up with one ear carrying the whole load . . .



Use a "sharpie' marker (color the contact areas of the bolt,put your go gauge in and move the bolt carrier.Points of contact will be wiped clean.File these areas lightly and recheck )

This method has worked many times for me.All my guns are shooters.They all get shot on a regular basis.When I first got into the hobby I wanted only "matching" kits for fear of headspace issues but now I tackle any.Moving the barrel is only required for headspace that is loose in my book. I'm just a Home Builder I don't have a complete metal working shop at my disposal.


I agree with greasebomb. This works. However, the best method is just to have a selection of extra bolts on hand to try. One will headspace.

:( I had a AK47 pistol that had a headspace problem, read this thread with great interest, everything from removing the barrel to filing the lugs...after digesting all the info I went with Mr. Greasebomb's recommendation to use a magic marker, work the action then file off the high spots...Hah worked great, in a half hour I had the bolt slamming home on my "parts" AK pistol..thank you Sir for the great info...Keep on filing, :skull_cro

:( I had a AK47 pistol that had a headspace problem, read this thread with great interest, everything from removing the barrel to filing the lugs...after digesting all the info I went with Mr. Greasebomb's recommendation to use a magic marker, work the action then file off the high spots...Hah worked great, in a half hour I had the bolt slamming home on my "parts" AK pistol..thank you Sir for the great info...Keep on filing, :skull_cro


There is a rotational helix, and you have to keep it. Make sure you remember that while filing.

Hi All,
Hope Silver doesn't mind me piggybacking on his thread.
Anyway, here's my headspace issue:
Yugo M70 build. The bolt will not close on the go and no-go gauges.
It will however close on a round. With 2 pieces of Scotch tape on the head of the round, the bolt is difficult to close. With 3 pieces of tape, the bolt will not close.
Any clues as to what's going on?
As always, thanks for the help.

Puck

American SAAMI spec guages are a little different from the ones the Euro AK factories used. As long as it easily closes on a selection of ammo it is OK, headspace is just a little tighter than American spec.

American SAAMI spec guages are a little different from the ones the Euro AK factories used. As long as it easily closes on a selection of ammo it is OK, headspace is just a little tighter than American spec.

Salute Kernel!
Thanks

Best to move barrel, not lugs. Anyone know the depth of hardening on an AK bolt? Are they hardened all the way through or case hardened?

American SAAMI spec guages are a little different from the ones the Euro AK factories used. As long as it easily closes on a selection of ammo it is OK, headspace is just a little tighter than American spec.

I've had numerous builds that would close on the CIP gage, but not on the SAAMI. I recommend avoiding the "ammo and tape" test, since ammo is much more variable than gages. Manson CIP spec gages are now available from Brownells for about $25, so I would recommend puckwall obtain a CIP GO for the added piece of mind.

Larry

PS: For more info, see: http://www.akfiles.com/forums/showthread.php?t=17887.

Thanks Larry. I need to order up some Gunkote anyway.

Valleyrat- I'm using the selector stop you sent me on this build.

American SAAMI spec guages are a little different from the ones the Euro AK factories used. As long as it easily closes on a selection of ammo it is OK, headspace is just a little tighter than American spec.


Agreed. I would add also: If the bolt closes on a round and is tight/snug against the lugs, HS should be fine. Try wiggling the bolt with it locked on a round, it should not move along the lug "plane."

There is lots of good information on the Internet on the subject of headspacing . . .

Excessive headspace is the more severe concern, since it can result in several unsafe outcomes. Among them is bolt slap which can eventually lead to failure of the locking lugs (there used to be a thread with photos on this on this forum).

Not enough headspace should just result in the bolt not locking. On most AK style rifles there is a tail on the bolt carriers that prevents the hammer from contacting the firing pin if the bolt is not locked. This feature should prevent out-of-battery detonation. However, I'm personally always a little leery about relying on such things . . .

As always, YMMV.

Larry

I've had numerous builds that would close on the CIP gage, but not on the SAAMI. I recommend avoiding the "ammo and tape" test, since ammo is much more variable than gages. Manson CIP spec gages are now available from Brownells for about $25, so I would recommend puckwall obtain a CIP GO for the added piece of mind.

Larry

Ok. I've looked around Brownells site and found the Manson GO gauge but it doesn't say anything about CIP. It does mention SAAMI standard through.
Is this the gauge I want?

http://www.brownells.com/.aspx/sid=19561/pid=25179/sku/GO_GAUGE__fits_7_62_x_39mm

Thanks

Ok. I've looked around Brownells site and found the Manson GO gauge but it doesn't say anything about CIP. It does mention SAAMI standard through.
Is this the gauge I want?

http://www.brownells.com/.aspx/sid=19561/pid=25179/sku/GO_GAUGE__fits_7_62_x_39mm


No . . . Here's the one(s) you want:

GO: http://www.brownells.com/.aspx/sid=51905/pid=25179/sku/GO_GAUGE__fits_7_62_x_39mm__CIP_spec_
NO GO: http://www.brownells.com/.aspx/sid=51904/pid=25179/sku/NO_GO_GAUGE__fits_7_62_x_39mm__CIP_spec_

Though it looks like the price is up $5 since I purchased them.

Larry

No . . . Here's the one(s) you want:

GO: http://www.brownells.com/.aspx/sid=51905/pid=25179/sku/GO_GAUGE__fits_7_62_x_39mm__CIP_spec_
NO GO: http://www.brownells.com/.aspx/sid=51904/pid=25179/sku/NO_GO_GAUGE__fits_7_62_x_39mm__CIP_spec_

Though it looks like the price is up $5 since I purchased them.

Larry

Got the gauge ordered up. I'll report my findings when it shows up.
Merry Christmas to all and to all a nice new case of ammo under the tree.

If I have a matching number parts kit won't the headspace be correct from the factory? I am gonna have it checked, probably by a gunsmith but I was just wondering.

If I have a matching number parts kit won't the headspace be correct from the factory? I am gonna have it checked, probably by a gunsmith but I was just wondering.

In theory, you're correct. However, there are a bunch of things that mess up the theory: The factory could have messed up, you could have shaved the pin or channel while reassembling, etc.

You may find that by the time your done paying a smith, you could have purchased the gages and done it yourself . . . besides, if an adjustment is needed, your going to have to slide the barrel around and then drill for an oversized pin. In this case you'll definitely need gages.

Larry

PS: On every Hungarian and Polish AK I've built, I've used a tapered pin to move the barrel back into factory alignment. Every time I try this technique on a Romanian, I've ended up shaving either the pin or the channel . . . and this is just one of the things that can go wrong.

http://www.reamerrentals.com/SearchResults.asp?Cat=141

http://www.4-dproducts.com/

may be a little cheaper way to go if you don't build a lot.

amd65 - generally yes the headspace on a matching# kit is correct from the factory 'as is.' but sometimes a builder can accidentally shave off a sliver of metal off the channel of the bbl on dissasembly etc., then the headspace can be altered due to damage done by biyr/builder as-Les has pointed out. in this case bbl needs to be adjusted-along with the hs checks. after that i read we have to drill slightly undersize for the new larger 8 mm oversize pin and ream the hole for a press fit if i got it right? yes no? hey, i am about to do this shit for very 1st time gents! lol

we have to drill slightly undersize for the new larger 8 mm oversize pin and ream the hole for a press fit if i got it right?

I generally go with an M (0.295”) drill and 19/64 (0.297”) pin for my first attempt. That gives me another chance with the 8mm, if I mess up.

In almost two dozen builds I've never reamed the hole, but I'm not enough of a machinist to know the pro's and con's . . .

Larry

No . . . Here's the one(s) you want:

GO: http://www.brownells.com/.aspx/sid=51905/pid=25179/sku/GO_GAUGE__fits_7_62_x_39mm__CIP_spec_
NO GO: http://www.brownells.com/.aspx/sid=51904/pid=25179/sku/NO_GO_GAUGE__fits_7_62_x_39mm__CIP_spec_

Though it looks like the price is up $5 since I purchased them.

Larry

Good news. Got the CIP go-gauge and the bolt does close on it. It's kind of tight but, it does close. Looks like I'm good to go.
Thanks a ton for all the help!

Puck

Good news. Got the CIP go-gauge and the bolt does close on it. It's kind of tight but, it does close. Looks like I'm good to go.
Thanks a ton for all the help!

Puck

It's suppose to be tight.

I generally go with an M (0.295”) drill and 19/64 (0.297”) pin for my first attempt. That gives me another chance with the 8mm, if I mess up.

In almost two dozen builds I've never reamed the hole, but I'm not enough of a machinist to know the pro's and con's . . .

Larrythanks Larry i'll have to jot this down... i also don't use or even have a reamer yet. but i just was going with what i read off the files somewhere. but it sounds like your way works also. my geuss is, as long as the cross pin fit is not a SLIP FIT, but rather a press fit-it's good to go. good info, again TY!

But - Les what drill bit size would you recommend foir an 8 mm pin? because i am not sure where i would find a 19/64" cross pin?

Les what drill bit size would you recommend foir an 8 mm pin? because i am not sure where i would find a 19/64" cross pin?

5/16” = 0.3125” & 8mm = 0.3149” press fit with 0.0024” interference.

I use 19/64” drill blanks and make my own pins . . . just cut to length with a Dremel. I don't bother to harden the drill blanks as they seem harder than the OE pins.

Larry

Tag for info

5/16” = 0.3125” & 8mm = 0.3149” press fit with 0.0024” interference.

I use 19/64” drill blanks and make my own pins . . . just cut to length with a Dremel. I don't bother to harden the drill blanks as they seem harder than the OE pins.

Larryty for the info! and good luck on ur builds. Jim