AK-47 Headspace and my bolt

[Gunor]

I put together a AK-47 (milled receiver and etc.) and pressed and pinned in the barrel.

Blah, Blah - I am little long on headspace. Long Story

Does any one know, if I could send my bolt to them and have them look thru their stash of bolts and find a better fit for my rifle?

Yes, I understand about head spacing and etc. And the liability question...

I have the front half of the milled receiver (original torched parts set) that can be used as a gage block. And I used that and my bolt carrier to gage the two extra bolts that I have.

I really don't want to send my gun to a smith....might just wait to a big gun show and see if some one has a bucket of bolts.....

I do have a GO gage and a nice Starrett depth gage...

Thanks

Geoff in Oregon

[HATCH]

I have built over 50 AK rifles over the years.
How long is a little long?
Are you talking 4 pieces of tape?

Get masking tape. Put a single piece over the bolt face and try to close the bolt on the go gauge
If it still closes then put another and another until it doesn't close any more.
then report back.
To be honest depending on how far off you are, you might need to press the pin out, push the barrel to the correct spot and drill for a oversize pin.

If it was me, I would press the barrel in to the correct spot and drill for a oversize pin.
You can use drill stock for the pin.

[Larry Gibson]

Yes, how long is "long"?

Larry Gibson

[Gunor]

How embracing, 5 masking tape thicknesses on a live round. Long time project, need to find my GO gage.

geoff in oregon

[Larry Gibson]

Bet if you had a field gauge you'd find the headspace was fine (according to com-bloc specs). Having TI'd several hundred AKs and SKS's for a company I worked for a few years back I say as long as the extractor snapped over the rim the "headspace" was "good"............

Larry Gibson

[HATCH]

clymer gauges from brownells
no go 1.3415 oal
go 1.341 oal

[seagiant]

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Hi,
Huh??? There's only .0005 difference between go and no go in an AK-47??? I sort of doubt that!

[HATCH]

That's what the internet said and when I ballpark take a measurement on my go/no go gauges there isn't much difference.

Bubba's way to do headspace was one piece of masking tap on the head of a live round.
If it closed on it then the headspace was excessive

I believe that 5 thousands on top of a live round is too much headspace.
Will the gun blow up no its a ak.

Masking tape is normally 1 mil thick or one thousands thick

[MtGun44]

AK don't need no stinking headspace! :kidding:

Believe what Larry says, they live with a LOT of headspace.

Bill

[seagiant]

Hi,
Found this! http://www.akfiles.com/forums/showthread.php?t=40192

[reed1911]

C.I.P. 7,62 x 39 TAB

http://www.cip-bobp.org/homologation/uploads/tdcc/tab-i/7-62-x-39-en.pdf

[seagiant]

Hi,
Found this! http://www.akfiles.com/forums/showthread.php?t=40192
Hi,
Ok, as I read it the difference from go to nogo is .005 and go to field is .010! That sounds more like it!

[lefty o]

throw the tape away, and buy some guages, or even just a field guage.

[Larry Gibson]

As long as the extractor snaps over the rim on chambering the headspace is fine. Kalashnikov did not refer to SAAMI or CIP headspace dimensions when he designed the rifle. The designers of the M43 cartridge didn't either. The extractor will hold the case back regardless of the headspace dimension from bolt face to datum line. The taper also holds the case back. All you'll be doing is blowing the shoulder forward if the headspace is a bit long; i.e. fire forming the case. If reloading the fired cases then adjust the FL die to size the cases to just fit the chambers headspace.

A lot of answers to a non-question. Go shoot the darn thing.

Larry Gibson

[Gunor]

Larry,

I have small hoard of boxer primed brass. I cause I'll assign it to this weapon only (not the SKS). If I have the money to buy a case of ammo - I would not be that concerned. I just wanted to get closer on the headspace to match my SKS - hence the stash of AK bolts. I am fairly sure there is a large range in bolts. I just don't want to overwork my brass...Neither are a target rifle in any sense.

But I did try to get my Benjamin barrels all fairly tight on head spacing for Palma and Across the Course rifles...

But again, the two rifle concepts are light years apart.

Reloading with a cast boolit and blasting is really all I want with this gun....I even got a Dillon setup for it finely. Just want to conserve my hoard of boxed primed brass. I did get some berdan brass (real brass cases) - saving $$ for a Graf shipment of Berdan primers.....

I do take donations of boxer primed 7.62x39 brass....or trade or even money....

And probably try to go to Portland for a big show and look for bolts....If I could get a few thousands or more...Cool

Geoff in Oregon

[reed1911]

Larry Gibson, I imagine you feel that SAAMI and CIP are non-applicable and since they are only voluntary standards they don't have to be followed and or can be ignored?

[HATCH]

Masking tape is a good bubba measure. 5 pieces means 5 thousands.
You should be fine based on the akfiles data.

[Gunor]

Gee guys...

Thanks Larry, understand about Russian designed weapons (and the other countries that copy and built them). In Afghanistan, I had some good and interesting times playing, fixing, and shooting some of these weapons (122mm and down).

Hatch, I'll have time this weekend to confirm the 5/1000 per layer ( I was thinking more on the tape I had....)


World Standards - I don't think I would have any problem shooting this AK with most ammo. When I was younger (and...) I shot a 308 in a '06 (M-1) - I keep that shell for a number of years...

Geoff in Oregon

[waksupi]

Masking tape is a good bubba measure. 5 pieces means 5 thousands.
You should be fine based on the akfiles data.


Better re-measure those five layers. That should be between .016 - .020. We used to use masking tape as a rough measure.

[HATCH]

Most standard masking tape is a mil thick. So 5 would be 5 thousands. If it is a mil thick then your fine. If it ends up being a lot thicker then its too much.

[seagiant]

Hi,
When I was building FAL's I bought a Forster GO Guage and then added tape to that for a NO GO! Cared less for FIELD!

You should have a good set of mics and calipers to make sure of what you are doing! I don't really buy into it's an AK-47 so headspace does not matter? A firearm is a firearm and it's my face next to it!!!

[waksupi]

Most standard masking tape is a mil thick. So 5 would be 5 thousands. If it is a mil thick then your fine. If it ends up being a lot thicker then its too much.

I've used four different brands for the purpose. I once again recommend you re-measure. Tightening your mic with a pipe wrench may get it that thin.

[HATCH]

Looks like the internet was wrong....
I just went to the 3m sight and looked up the cheapest masking tape they sell. http://solutions.3m.com/wps/portal/3M/en_US/Adhesives/Tapes/Products/~/3M-Value-Masking-Tape-101-?N=5000130+3294262930&rt=rud

Thickness is stated 5.1 mill.

So 5 peices is .0255 off
Thats a little much for any gun.

[HangFireW8]

I tried the masking tape thing. Turns out masking tape is compressible, especially when layered. Now I buy gauges.

[Larry Gibson]

Larry Gibson, I imagine you feel that SAAMI and CIP are non-applicable and since they are only voluntary standards they don't have to be followed and or can be ignored?

You imagine incorrectly. Headspace is important but the concept of "headspacing as used by the Russian military was not exactly along our lines or that which came later. The point is neither SAAMI or CIP were around when the cartridge, the SKS, the AK, the RPD or the RPK were designed or when the chamber specification for the M43 cartridge was adopted and made. The extractor is such on those weapons that if it snaps over the cartridge rim it holds the case against the bolt face. The rifle fires and the case fire forms foreword. Same as in a CF action. Again, if the rim snaps over the cartridge rim the case then there is "headspacing" of the cartridge. It has has occurred due to the taper of the case (ever notice the taper of a M43 cartridge and wonder why?) more so than from the small shoulder. It is safe to fire. If the rim does not snap over the case rim then the firing pin (if dimensioned correctly) probably will not reach the primer and the rifle will not fire anyway. If the headspace is that long so as the extractor does not snap over the cartridge rim then I doubt a "bucket of bolts" will solve the problem.

The OP certainly is not bound to take any advise from me or anyone.

Larry Gibson