Ejection problem

[bodiebill]

Built a Polish UF, the 7.62x39mm cases are not fully ejecting then jamming the action.
They seem to be extracting OK, but could it be a worn extractor losing its grip during the process?
The kit obviously saw field duty
What else should I look for?
Cannot see any visible evidence on the spent brass to lead me to the problem.
Bodiebill

[Alex$]

Measure your ejector, sounds like it was taken down too much leading to fail to eject.

[ott1]

Ejector too short.

[bigbob76]

Hey Bill, do you have any dummy rounds to work with? If you put a few dummy rounds in a mag, take the top cover off and watch what happens as you cycle the action.

[Dan FS71]

never hurts to check the unlikely and since you asked.

The gas port could be to small. Easy to check with a drill bit on the 45 deg gas blocks.

Gas block to barrel fit. If it is / was a rather loose fit (less than or only slight press fit) it could be a gas leak. Look for black smugges around the barrel where the block sits.... Happens to m70's often but is usually a worn gas cutoff barrel in that case.

Gas piston could be too short, or the gas block could have considerable erroision. Common on the romy rpk's (errosion issue) In the case of an odd piston it would be dumping out the vents.

Not a polish guy but I belive the vents are on the tube like the m70. Sometimes on a mix master with gas dumps on the gas block and tube it may short cycle.

All things being equal my money is on the ejector like the rest. Likely too short... less likely the forward profile has changed.

To check this: Take the reciever cover off and recoil spring push the bolt /bolt carrier forward until even with the leading edge of the ejector and see just how deep it runs in the bolt face channel.

[moulton]

I had the same problem with my Polish under-folder not even three weeks ago, I trimmed the extractor to fit my bolt when I had them welded on. The extractor fit perfect but after riveting the center support and welding again the receiver warped ever so slightly so that it would not catch the case. I had another member of the board weld on a bit to the extractor and now it runs like a champ.

[ott1]

This is one reason that trimming the ejector is one of the last things I do when building an AK.

[CIV Tactical]

make sure your ejector is running square with the ejector cut in the bolt as well. I had a underfolder with the same symptoms then noticed the ejector was slightly canted down causing the extracted casing to barely engage with the top corner of the ejector. I bent the that section of rail slightly up to run square with the ejector cut and have not had a problem since. If your ejector is to short, you can TIG weld it up and reshape it to fit. If you do weld on it its important to polish the weld to shiny metal then normalize it by bringing it back to blue with a map torch, If this isnt done your ejector will break off due to brittleness.

[bodiebill]

Ejection problem Pol UF

Hey Bob
Thanks for your response on CalGunsNet to my ejection problem.
I will make up some 7.62x39 dummies and watch the action process as you recommended.

This kit had a bent rear trunnion; it is a weld ment. I did my best to make it straight and square it before I riveted it to the receiver, but noticed that I have a little hang up when I cycle the bolt slowly. It seems to function OK when cycled with vigor.
I measured the distance from the left outside of the receiver to the tip of the ejector and got 0.577 inches. I also measured a proper performing Romy at 0.547 inches. I know this is just comparative measurements between two different guns but the ejector tip appears to be deep enough in the bolt slot for proper ejection.

I attempted to take some photos which are attached; tough angle so they are not the most revealing.

I do see some bright rub marks on the right rail so perhaps it just might be a matter of break in or some fine honing to relive the tight spots.

Any other ideas would be appreciated.
Bill

PS Any good sources for US made barrels lately? We used Montana Rifle bbls last build but the prices have jumped.

[ott1]

I measured the distance from the left outside of the receiver to the tip of the ejector and got 0.577 inches. I also measured a proper performing Romy at 0.547 inches. I know this is just comparative measurements between two different guns but the ejector tip appears to be deep enough in the bolt slot for proper ejection.

Richard mentioned in another thread that optimum ejector tip length as measured between receiver and tip should be between 0.550" and 0.560". It seems like your ejector is just a tad too long and may be pushing the bolt towards the right of the receiver and causing hangups during slow racking.

[Richard Erichsen]

Richard mentioned in another thread that optimum ejector tip length as measured between receiver and tip should be between 0.550" and 0.560". It seems like your ejector is just a tad too long and may be pushing the bolt towards the right of the receiver and causing hangups during slow racking.

This is where it tends to end up if everything else is within spec. Rub marks per the description above tells me something is out of sorts.

R

[Richard Erichsen]

This kit had a bent rear trunnion; it is a weld ment. I did my best to make it straight and square it before I riveted it to the receiver, but noticed that I have a little hang up when I cycle the bolt slowly. It seems to function OK when cycled with vigor.

Sounds like a torqued receiver to me. Until you get it squared and plumb, setting ejector length based on an in-spec receiver isn't going to help you. Start with what may be the root cause and work your way back. A new stock trunnion is inexpensive and in less than an hour of your time, can be fixed. If you need help, the AK Team can help you, or you can book a one hour slot with Roccobro in San Bernardino.

I measured the distance from the left outside of the receiver to the tip of the ejector and got 0.577 inches. I also measured a proper performing Romy at 0.547 inches. I know this is just comparative measurements between two different guns but the ejector tip appears to be deep enough in the bolt slot for proper ejection.

The Romanian ejector is a bit short, but if it functions, leave it alone. Ejectors wear over time and as they get much shorter than .550", failures to eject can start happening more and more often. I'll bet the Romanian AK has a slight inward bow for that ejector length to be working consistently. On the rifle giving you issues, that is a very long .577" ejector on a 7.62x39 mm weapon (though about perfect on an AK74). The bolt head is likely being pushed to the side and causing rubbing unless the receiver has a slight outward bow, which I'm assuming it does or the bolt would just hang at an ejector that long.

I do see some bright rub marks on the right rail so perhaps it just might be a matter of break in or some fine honing to relive the tight spots.

See above. I think the rub marks correspond to the bolt group being pushed to the right by the ejector.

PS Any good sources for US made barrels lately? We used Montana Rifle bbls last build but the prices have jumped.

Green Mountain and AK Builder. Nuff said.

R

[Gunsmith Dan]

Do 1 simple test to eliminate something that I think might be your problem:

Bolt open slide a dummy round up the bolt face into firing position (not knowing the condition of your rifle I will not recommend you using a live round to do this)

Is the extractor hook on the side of the rim opposite the bolt face? If yes then:

Point your rifle upwards at a safe spot in a 45 degree angle (does not have to be exact) and rotate, swirl it, in a circle to cause the round to move around. Does the round stay on the bolt face with no sliding down out of firing position?

I am thinking your extractor is either the wrong cut angle or the hook partially broke off.

Hope this helps

[Richard Erichsen]

Do 1 simple test to eliminate something that I think might be your problem:

Bolt open slide a dummy round up the bolt face into firing position (not knowing the condition of your rifle I will not recommend you using a live round to do this)

Is the extractor hook on the side of the rim opposite the bolt face? If yes then:

Point your rifle upwards at a safe spot in a 45 degree angle (does not have to be exact) and rotate, swirl it, in a circle to cause the round to move around. Does the round stay on the bolt face with no sliding down out of firing position?

I am thinking your extractor is either the wrong cut angle or the hook partially broke off.

Hope this helps

He might as well do the "shake test" with the bolt carrier out of the rifle. If a gentle shake of the carrier with a round clipped into the extractor claw causes that round to fall out, the extractor spring is too weak or the extractor itself worn and out of spec.

Even a live round can be used since the carrier will not be in the rifle. A new extractor spring or extractor will be cheap and only require knocking out a few pins to access both the extractor and spring.

R