PSL-54C front trunnion crack; minor or major?

5881 Views 16 Replies 12 Participants Last post by 1biggun, Apr 24, 2010

Comm Bloc Steel Core

Discussion Starter · Apr 23, 2010

Hey everyone, I have a relatively new (2 months since first use) PSL-54C from Century and upon breaking it down and cleaning it yesterday I noticed there is a fine hairline crack in the front trunnion that runs parallel with the barrel pin only on the top half of the trunnion. Under the pin there are no cracks in the trunnion. I'll attach a picture of a yugo trunnion to give a visual of the crack. If it were something besides a rifle I'd repair it with an oxy-acetylene welding torch, but I have to keep this thing kind of close to my face when i use it so I cant just pull a "What the hell, It'll be fine!" descision without some input. So is it minor, major, weldable or a full blown return it to Century immediately kind of problem?

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1 - 17 of 17 Posts

555th

· #2 · Apr 23, 2010

It's scrap now. Return it if you still can or replace the trunnion yourself.

hcpookie

· #3 · Apr 23, 2010

I've never heard of a cracked trunion before. I would agree to return it

Bradrock

· #4 · Apr 23, 2010

Century monkey forcing a too large barrel pin???

Comm Bloc Steel Core

Discussion Starter · #5 · Apr 23, 2010

...awesome...I wish I would have noticed that before I went to the trouble to refinish the stock and fix the canted front sight assembly. I thought I was buying a rifle and I got a parts kit. If they don't take it back its going to cost more to repair than it is to get a new one.

If all else fails with a century return, it's a definite no-go for a weld the crack shut option?

Ok, just for the sake of curiosity here's a hypothetical situation...a century return is impossible due to Zombies, you cant get a spare trunnion due to Zombies and you're inside a machine shop and a questionable PSL is your only rifle to fight off the soon to be in your area Zombie horde...how do you fix a crack like this one?

(keep in mind i'm praying for a Century return...but if all else fails what do you do? Use it like a club?)

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Comm Bloc Steel Core

Discussion Starter · #6 · Apr 23, 2010

yup...the feller just pounded it in there until it fit...then they painted over it and slapped it on the "rifle"...ive put about 200 rounds through it before i realized its a crack...it looks like a scratch until the gun heats up and the trunnion expands a tiny bit.

Viper Dude

· #7 · Apr 23, 2010

Hello CBSC,
That crack ain't cool !!!
Crack kills !!! Return that bad commie gun to Century as it is a hazzard to life and limb. They should be very happy to replace that defective item before it totally fails, injurs, and causes a mega-lawsuit. Contact them first in writing before returning. If your letter is ignored have an attorney write them a letter.

VD

Icarus

· #8 · Apr 23, 2010

I am not fond of century, but I bet they will be glad to make that good, if they dont, wait 2 weeks and call them back and tell them some unaware of crack took rifle out and it KABOOMED on them and they are in really bad condition, that will get some response Ill bet

hcpookie

· #9 · Apr 23, 2010

Comm Bloc Steel Core said:
...awesome...I wish I would have noticed that before I went to the trouble to refinish the stock and fix the canted front sight assembly. I thought I was buying a rifle and I got a parts kit. If they don't take it back its going to cost more to repair than it is to get a new one.

If all else fails with a century return, it's a definite no-go for a weld the crack shut option?

Ok, just for the sake of curiosity here's a hypothetical situation...a century return is impossible due to Zombies, you cant get a spare trunnion due to Zombies and you're inside a machine shop and a questionable PSL is your only rifle to fight off the soon to be in your area Zombie horde...how do you fix a crack like this one?

(keep in mind i'm praying for a Century return...but if all else fails what do you do? Use it like a club?)

I understand your question.

Trunions are among the only pieces of an AK receiver assembly that need to be heat treated at the locking lugs. It is generally assumed that they are at least surface hardened everywhere else. My personal experience has been that they are softer past the surface, as anyone who has drilled one for a larger barrel pin or drilled for tapping screws would assert.

Thinking this through - this is the "starting point" for setting headspace, and if that drifts then headspace will be altered accordingly. Left as-is, it would probably move forward over time and open up headspace slightly.

There's also the chance that the now-loose barrel pin could hammer the pin hole and egg it out some. We're talking a LOT of hammering which on a PSL I doubt you'd ever see.

THAT BEING SAID...

7.62x54R is a 50,000 PSI cartridge. That's 25 tons of force on that area. If you put that in a 25 ton bearing press and crank it all the way down, that's how much force is asserted against that area for that nanosecond impulse when the powder is ignited.

Personally, I would consider a GOOD weld would fix it. A good weld should be able to withstand 25 tons of force. It is steel after all... not like welding an engine block casting or something like that. See if you can get the trunion heat treated after the weld. I know others with more metalurgy insight will be better able to answer, but I wonder if it would need to be heat treated after the weld, or if that would do more damage.

Re-do the barrel pin after checking headspace... if the weld opens up the hole then you'll need to redrill for a larger pin. Check headspace after every magazine and see what happens over time. If it DOES change slightly over time then you should consider it beyond repair and buy a new trunion.

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ACMcom

· #10 · Apr 23, 2010

IIRC Century has a warranty that runs one year from the date of purchase.
If you've had the rifle longer than that, ask them if it's a safety problem. The potential liability might get them to replace the rifle.

Comm Bloc Steel Core

Discussion Starter · #11 · Apr 23, 2010

Looks like I'll be calling Century on Monday to see what can be done, thanks for the input...the more I hear about this the more I'm sure they will probably make it right...If not I may dust off the video camera and get a few spam cans out, vise the rifle to a bench and run ammo through it until it fails (using a long string on the trigger) and then send Century a copy of the video and see if they rather send me a replacement or if they rather have their handy work literally exploding all over youtube...

Again thanks to everybody for their help. Hopefully I can get a repair or a replacement. I'll post the results on monday. Thanks!

Markp

· #12 · Apr 23, 2010

It could be welded... However I would want to re-heat treat the whole thing. The good news is that the barrel pin is holding the 25 tons of force and not the trunnion in this spot.

Still best option is to return and replace.

Mark

[486]

· #13 · Apr 23, 2010

Markp said:
It could be welded... However I would want to re-heat treat the whole thing. The good news is that the barrel pin is holding the 25 tons of force and not the trunnion in this spot.

The barrel pin holds most of the pressure, and there ain't much metal besides that top part [that's cracked right now] that holds that pin from flying forward. :wow: Get it replaced, if it can't be replaced by them, you could probably dremel a cheapo yugo trunnion to fit. Prolly a beefier trunnion than the romy one anyways... Heck, if you end up fixing it, while the barrel's still out you could lap the bolt lugs without having to worry about headspace.

Viper Dude

· #14 · Apr 24, 2010

Cylindrical pressure vessel stress (ie chamber) consists of hoop and end plate loadings. In this case it is end plate loading opposite the breech. Of the 50 ksi pressure the breach sees 50 ksi x its' opening area or about .25 x .25 x 3.14 x 50 ksi = 9.817 ksi , not quite 10 thousand pounds stress max.

The problem with rewelding the damage is not what you fix but what you have created in doing so. Depending upon the specific steel used and the amount of weld heat applied vs the cool down rate you end up with an unknown condition. Too soft a condition may be "OK" but... too hard ie brittle may allow the receiver to fracture catastrophically. The later is the greatest concern.

The receiver may not actually explode like a frag but can allow the barrel to blow forward making excessive headspace and cartridge rupture. That allows brass/steel case material and burnt gas to blast you in the face at extreme velocity.

VD

j427x

· #15 · Apr 24, 2010

being of unknown heat treatments and hardness i think a replacement would be the best course of action.

if you had new good steel to weld, a weld would be fine. but on some old commie steel that can be a risky venture.

weld would likely hold it well enough but if that steel is brittle it might get more brittle around where the weld is made.

SJgunguy24

· #16 · Apr 24, 2010

hcpookie said:
I've never heard of a cracked trunion before. I would agree to return it

We had an AMD 65 kit (Unfired and pristine I might add) with a cracked trunion. From the way that one looked it was someone trying to pull the barrel before popping the pin first.
Yes, get a new trunion, that crack could open up and lead to case ruptures when head space gets execessive. No bueno

1biggun

· #17 · Apr 24, 2010

Ok, just for the sake of curiosity here's a hypothetical situation...a century return is impossible due to Zombies, you cant get a spare trunnion due to Zombies and you're inside a machine shop and a questionable PSL is your only rifle to fight off the soon to be in your area Zombie horde...how do you fix a crack like this one?

You dont fix a crack like that its junk. It holding considerable force.

You mentioned you straightend a canted part. How was this done??? Are you sure it was like that when you got it???

If they wont return it you need to repalce or hgave it done. welding on a truniom is a NO NO IMOO

The gun is very unsafe to shoot.

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