AK 47 headspacing question.

[anthonywwalker]

After shearing off a foot and a half piece of allthread and embedding it into my garage wall, I broke down and bought a press (harbor freight 20 ton, regular $229, on sale for $169 and I dropped a 25% off coupon on em). I got my barrel pressed in, using the scoring marks on the trunnion from the original barrel as a starting reference. I have a set of go/no go headspace gauges but the bolt closes and locks up on both. This doesn't seem right.

Also, I was under the impression the no-go gauge was supposed to be longer, but my go gauge is actually .2 mm longer than the no-go. Most likely I'm just doing something wrong and don't know how to properly use my tools. Any advice?

[BR7.62]

that is wierd about your gauges measuring like that. might just be the cone at the front that doesnt touch the chamber walls showing that measurement?
sounds like it needs pressed in further.
i like to make it quite tight on the go gauge.
this ussually makes a nice fit on most of my ammo.
can you lock them both and wiggle the bolt front to back at all?

[anthonywwalker]

Yeah, I still have a bit of wiggle with them both locked down. As far as the gauge measurements, I measured them with digital calipers before I started checking the headspace.

[BR7.62]

keep pressing! just go a touch then check until you get it.
maybe google search for videos. would give you a better idea what youre looking for.

[FTC]

Is the barrel original? How's the pin hole look? You cant measure the gauges with a caliper, they measure off a point mid taper on the shoulder

[anthonywwalker]

Its a virgin barrel that came with my Romy kit. After watching a few vids and such, it appears as though I need to press it in a bit further.

[nicoroshi]

the distance of the gauges that is important is from the bolt face to the datum line NOT the front of the gauge.

Also there are different guages available, and if doing an AK you need to use the Russian spec ones not US spec.
The bolt should close snug on a GO guage, and should not close on a No-Go gauge.
Example>>>


If it closes on both the go, and no-go you need to press t he barrel in further until it can close snug on a go, and not close on a no-go.

[anthonywwalker]

Thanks Nico, this helps a ton.

[anthonywwalker]

Thanks Nico, this helps a ton.

[nicoroshi]

Gotta love visual aides

Head space is not something to monkey around with, and the tolerance is very small between a go, and no-go gauge (~.005").
Check multiple times.
Set, check
Drill/ Ream, check again
Set Pin, check again
When pressing barrel back in after trunnion is in receiver, check again
Then for giggles, check one more time
40K lb/in2 is not something you wanna be wrong on.

[Anti-Hero]

Could it be that the chamber was cut too deep on the virgin barrel? I've read a lot of disconcerting reports of US made barrels being way out of spec. on some AK builds.

[anthonywwalker]

I was gonna buy something with that harbor freight coupon, but I go to order and everything is marked up 25%, the 20 ton press is now $250. I dont see any items that are discounted in red like they usually are

I really wanted to use it for a compressor, but the coupon stated that it couldn't, even tried to slip it past the cashier, but she was onto my tricks and shot it down

[anthonywwalker]

So I pressed my barrel in a bit more this morning before work. Pressed, checked, pressed, checked. Was still off by just a hair so I pressed it one more time and it popped and jumped about a mm too far and now it won't close on either gauge. GRRRR I had to seriously fight off the urge to press it back out a hair but I would've been late for work. Damn shame a man has to work to afford his hobbies, leaving him precious little time for aforementioned hobbies. Thanks again for the clarification Nico, I knew exactly what I was looking at and looking for after your explanation and pics.

[nicoroshi]

You're welcome.
Little trick for you.
When applying pressure to press in dont go all the way until it pops too far.
Apply some pressure then hit the ram of the press with a mallet.
It will wiggle it just enough to move just a little rather than building up a lot of pressure and jumping a lot.

[klewan]

Could it be that the chamber was cut too deep on the virgin barrel? I've read a lot of disconcerting reports of US made barrels being way out of spec. on some AK builds.

That was the case probably 2 or 3 years ago. From what I read, S&W used a .223 barrel diameter for their 5.45x39 upper instead of the .214. Other barrel makers copied S&W, so theirs weren't right either. Another barrel maker shipped .223 barrels instead of the .214, lots of key holing problems. All of these were 5.45, never really saw 7.62x39 being butchered to this extent.