AK ejection problem

[SJgunguy24]

This forum has sure come a long way. Is was only a few years ago when guys would not even admit to having a short ejector let alone talking about it in public and asking for help to resolve it's shortcomings.

IMO it takes more of a man to admit to their problems and have the courage to ask for help. Vs the guy who keeps doing the same thing but expects a different result.
I know that sounds a little 12 stepish there but it's a good lesson to learn and apply to every aspect of a persons life.

[Richard Erichsen]

Since I don't have access to the shop anymore I can't measure the ejector for you. Ideally you want the ejector to fill that area of the bolt with as little drag as possible. I like to put a blob of weld material on there and file fit everything. Watch highspeed videos and see how much that receiver flexes and you'll see why you want a fat ejector.

What sort of weld rod are you using for that and what sort of hardening are you able to perform afterwards? Welding some material to the tip makes intuitive sense, but if the rod being used is a mild steel then there will be no way to harden it without resorting to some very odd jigs to case harden a small point or similar weirdness.

R

[SJgunguy24]

What sort of weld rod are you using for that and what sort of hardening are you able to perform afterwards? Welding some material to the tip makes intuitive sense, but if the rod being used is a mild steel then there will be no way to harden it without resorting to some very odd jigs to case harden a small point or similar weirdness.

R

The deposit is hardend from welding. I usually keep er70s2 in my mig machine as my all around wire .030 and er70s6 .062 for the tig.

[Panchira!]

Funny as I built mine from a ak builder flat and once complete the ejector tang was sticking out to far. I filed it down to where it just clears the bolt no problems at all.

[SJgunguy24]

Funny as I built mine from a ak builder flat and once complete the ejector tang was sticking out to far. I filed it down to where it just clears the bolt no problems at all.

Not every kit is the same. Some bolt and bolt carrier combos can have excessive play and receiver flex can do odd things to guns, like causing a reliable gun in slow fire to miss kicking a round out in rapid fire.

Look at the barrel whip and the receiver flex in this video.

[Richard Erichsen]

The deposit is hardend from welding. I usually keep er70s2 in my mig machine as my all around wire .030 and er70s6 .062 for the tig.

That's great info.

I just looked it up at Welding Material Sales and they list the wire chemistry for the ER70S2 as:

C 0.07
Si 0.50
Mn 1.10
Ti 0.10
Zr 0.08
Al 0.10

And for ER70S6:
C 0.07
Si 0.80
Mn 1.45

Plenty of carbon in there to harden it along with other alloying elements associated with "shock resistant" steels. The "Sx" series (S1, S5, S7) have roughly the same critical temperatures with the S5, S6, S7 series having a higher tempering temperature than S1, S2, S3 (I show 1100 F to achieve a final HRC in the 45 HRC range).

R

[69powerwagon]

That's great info.

I just looked it up at Welding Material Sales and they list the wire chemistry for the ER70S2 as:

C 0.07
Si 0.50
Mn 1.10
Ti 0.10
Zr 0.08
Al 0.10

And for ER70S6:
C 0.07
Si 0.80
Mn 1.45

Plenty of carbon in there to harden it along with other alloying elements associated with "shock resistant" steels. The "Sx" series (S1, S5, S7) have roughly the same critical temperatures with the S5, S6, S7 series having a higher tempering temperature than S1, S2, S3 (I show 1100 F to achieve a final HRC in the 45 HRC range).

R

I beg to differ that those fillers are hardenable. Those wires are specifically designed to be ductile and forgiving of the base metal and surface condition of the weldment, hence the use of three deoxidisers, extremely low carbon, and the low manganese. You do not see benefit of heat treating until about .25-.30% carbon. The aluminum is present to make the bead wet well. The reason that I believe it sufficiently hardens without heat treatment is due purely to the 4130. 4130 contains about .28-.33% carbon with a carbon equivilent of about .65% from the other alloying elements, once you dilute the 4130's carbon into an extremely ductile filler you drop the carbon content enough that it is now no longer prone to cracking but still high enough %c to facilitate the formation of enough martensite (what make these steels hard) to make the ejector hard enough. I guess the point of this ramble is not too say that the ejectors are being done wrong(which I don't think they are being done incorrectly), but purely to say the er70 series fillers are not hardenable. I hear it said far too often that they are

[Richard Erichsen]

I beg to differ that those fillers are hardenable. Those wires are specifically designed to be ductile and forgiving of the base metal and surface condition of the weldment, hence the use of three deoxidisers, extremely low carbon, and the low manganese. You do not see benefit of heat treating until about .25-.30% carbon. The aluminum is present to make the bead wet well. The reason that I believe it sufficiently hardens without heat treatment is due purely to the 4130. 4130 contains about .28-.33% carbon with a carbon equivilent of about .65% from the other alloying elements, once you dilute the 4130's carbon into an extremely ductile filler you drop the carbon content enough that it is now no longer prone to cracking but still high enough %c to facilitate the formation of enough martensite (what make these steels hard) to make the ejector hard enough. I guess the point of this ramble is not too say that the ejectors are being done wrong(which I don't think they are being done incorrectly), but purely to say the er70 series fillers are not hardenable. I hear it said far too often that they are

What would you recommend for a hard-enable fill wire?

R

[69powerwagon]

Hopefully there aren't too many other welders reading this, because there are as many methods as there are welders(kinda like painters that way).

One way is to use 4130 tig or mig wire(I recommend tig), this wire is almost identical in composition to the original steel. First anneal your ejector by heating and air cooling, then build up with your 4130 filler, grind or machine to shape, heat, quench, and temper.

You can also use er420 filler, it is stainless and will not match in color. This wire is more expensive and somewhat elusive. First anneal your ejector, then weld it, grind it to shape, good to go as long as the shell contacting surface is weld since the as welded hardness is about 51 rc.

The concept of annealing when welding 4130 filler on this thin of metal is much debated, I personally don't think it is necessary due simply to it's thin-ness. The worry with not annealing is that you will have an embrittled heat affected zone.

I included a few links, but other companies also sell these fillers. As far as the 420 filler, I'd use tig so a trimix shielding gas is not necessary. In a few months when I'm able, I plan on testing a full range of fillers, heat treatments, toughness, and hardness tests as I will have access to a rockwell tester.

http://products.esabna.com/EN/home/filler_metals_catalog/filler_metals_part_no_detail/q/display_id.id4367f2a96cada0.13220946/product_id.1921/category_id.1003

http://weldingdesign.com/welding-qa/post-weld-stress-relief/

http://www.weldingwire.com/applications/DocumentLibraryManager/upload/420.pdf

[sd_shooter]

AK Ejector specs:

AK47: 0.560"
AK74: 0.580"

Measure from the outside of the receiver to the end of the ejector tip. Buy a set of $10 calipers if you don't have them already.

[Richard Erichsen]

Hopefully there aren't too many other welders reading this, because there are as many methods as there are welders(kinda like painters that way).

One way is to use 4130 tig or mig wire(I recommend tig), this wire is almost identical in composition to the original steel. First anneal your ejector by heating and air cooling, then build up with your 4130 filler, grind or machine to shape, heat, quench, and temper.

You can also use er420 filler, it is stainless and will not match in color. This wire is more expensive and somewhat elusive. First anneal your ejector, then weld it, grind it to shape, good to go as long as the shell contacting surface is weld since the as welded hardness is about 51 rc.

The concept of annealing when welding 4130 filler on this thin of metal is much debated, I personally don't think it is necessary due simply to it's thin-ness. The worry with not annealing is that you will have an embrittled heat affected zone.

I included a few links, but other companies also sell these fillers. As far as the 420 filler, I'd use tig so a trimix shielding gas is not necessary. In a few months when I'm able, I plan on testing a full range of fillers, heat treatments, toughness, and hardness tests as I will have access to a rockwell tester.

http://products.esabna.com/EN/home/filler_metals_catalog/filler_metals_part_no_detail/q/display_id.id4367f2a96cada0.13220946/product_id.1921/category_id.1003

http://weldingdesign.com/welding-qa/post-weld-stress-relief/

http://www.weldingwire.com/applicati...upload/420.pdf

I've been looking for an explanation this good for quite some time. You get a star on your chart! Now set EVERYONE ELSE straight.

R

[tujungatoes]

Ok now that we're all a little more metallurgically edjumacated.

What gives Mark? Did you figure out what was causing your FTE's?

[Mark51]

So I finally got a chance to measure my ejector. It measures 0.526” (from the outside of the receiver) at the front most part of the tip and 0.534” at the rear portion of the tip so it sounds like it might be too short based upon the spec posted by sd shooter.

I’m guessing I need to get a bead welded on the ejector, using the rod specified by 69powerwagon, to widen it up.

If I am reading SJguyguy24 post correctly it sounds like you widen and thicken the ejector up with a bead and file it down until it just clears the bolt. This certainly makes sense to me but in trying to envision fitting it this way I’m having a tough time due to the side-to-side and top-to-bottom play between the bolt carrier and the rails. Would I fit it so it just clears the bolt with it pushed all the way over to the left side?

I took the bolt apart and everything looks clean and seems to function fine. The extractor spring looks fine and seems quite stiff so I’m thinking it is okay. I don’t have another one to compare it to but I had to push on the extractor surprisingly hard to get it to move with my finger.

[Alex$]

Ejector should just clear bolt with bolt centered in rails. Or if you wish, press bolt toward dust cover and trim ejector to just clear. This will result in bolt peening the ejector for clearance, then it will be fine as long as you heat treat ejector afterwards.

I'd go with bolt centered first and if that isn't good enough, gopeening route.

[sd_shooter]

Would I fit it so it just clears the bolt with it pushed all the way over to the left side?

IMO, you should lengthen the ejector such that it still fits with the bolt touching the right rail of the receiver. After this, as long as there is no binding, you're good to go.

I wouldn't worry too much about the bolt being centered as it passes by the ejector. As the bolt travels back it is most important to get plenty of the ejector in contact with the empty case.