Mac 11/9 custom work -sear work

Generalzip

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I'm definitely not an expert but reading this and from years of reading peoples problems and people marking mags to diagnose problems, was the run away with any mag or just one mag?
What would the mag have to do with it? He replaced the sear and bolt and used the same mag it occurred in for hundreds of rounds with no issues
 

Homer

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If putting the magazine in the gun caused it to release the bolt then it had at least a little bit to do with it. Since you can't put the same ammo back in there's no way to know if it was or wasn't weak ammo. As someone said, just replacing some parts doesn't tell you what really caused the runaway.
 

Homer

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Could slamming the mag in cause it to over insert and raise the bolt higher than the sear catch?
 

Generalzip

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Could slamming the mag in cause it to over insert and raise the bolt higher than the sear catch?
The mag does not contact the bolt when inserted. The violent movement of slapping the mag in was enough to release the work seat and bolt.

I called Sam at practical solutions. Super nice and knowledgeable guy. Once the form 4 clears to my dealer I’m going to send to him for a full inspection and make any repairs as required. Will also see if he can install a semi feed ramp in my Uzi at the same time.
 

MitchWerbellsGhost87

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Based on what was described to me I think this is the best answer of what happened in this particular case. Would it not be wise then to slightly file the sear stud or part of the sear to slightly increase sear height say 1mm additional? Just to be extra safe and prevent this? Also ensuring sear to bolt contact is perfectly perpendicular would help too I’d imagine.
You should not have to alter the stud, you don’t want it to stick up too high either. Replacing the bolt (and sear just to be safe) should suffice. the sear is probably still serviceable, it seems like the sear outlasts a lot of those OEM bolts but it’s a 30 dollar part and worth replacing. I don’t really know much about the LAGE parts personally, but I see a lot of guys recommending the hardened LAGE sear. I personally will always recommend that you go with OEM parts when replacing the internals in the SMGs but the LAGE could be a nice upgrade. Keep in mind even OEM replacement parts often require a little bit of fitting due to fluctuating tolerances over the years and the LAGE may be the same way.
 

Generalzip

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You should not have to alter the stud, you don’t want it to stick up too high either. Replacing the bolt (and sear just to be safe) should suffice. the sear is probably still serviceable, it seems like the sear outlasts a lot of those OEM bolts but it’s a 30 dollar part and worth replacing. I don’t really know much about the LAGE parts personally, but I see a lot of guys recommending the hardened LAGE sear. I personally will always recommend that you go with OEM parts when replacing the internals in the SMGs but the LAGE could be a nice upgrade. Keep in mind even OEM replacement parts often require a little bit of fitting due to fluctuating tolerances over the years and the LAGE may be the same way.
Sam actually mentioned he recommended OEM sears as they are not as hard as the Lage and a little easier on the bolt. Cheaper to replace a sear than a bolt. In my opinion I don’t care about the money difference. The cost of ammo before you wear out a 250 dollar bolt far outweighs that cost.

Do you guys have any idea how long a new CNC bolt like a FTF should last with a Lage sear?
 

skoda

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That will depend on how you shoot. If you are shooting three round bursts the sear has to stop the moving bolt ten times per magazine. If you only do mag dumps then it never really stops the bolt (not counting a slow motion when cocking it)

The Lage sear is wider than the OEM and is a bit harder/tougher too though I have worn mine out after many thousands of rounds with both the steel and tungsten bolts. I don't think that it was all that hard on the bolts but it was easy to dress the sear engagement on the bolts and keep using them. To me the sear is the throw away part but your mileage may vary as they say. Undoubtedly Sam at PS has seen a lot more so go with his recommendation if that gives you peace of mind. In the end you have to monitor your gun (any gun) for wear; when you clean it is a great time to do that.

I do HIGHLY recommend the Lage safety. The OEM internal piece is die cast aluminum or zinc and is a POS. The external safety tab is tiny and not so easy to manipulate.

Richard is right about wimpy loads. I had a run on with light bullets and lighter powder charges in my .380. There was just enough energy to cycle the bolt far enough back to strip and fire the next round but not push it back far enough to catch the sear.
 

Generalzip

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That will depend on how you shoot. If you are shooting three round bursts the sear has to stop the moving bolt ten times per magazine. If you only do mag dumps then it never really stops the bolt (not counting a slow motion when cocking it)

The Lage sear is wider than the OEM and is a bit harder/tougher too though I have worn mine out after many thousands of rounds with both the steel and tungsten bolts. I don't think that it was all that hard on the bolts but it was easy to dress the sear engagement on the bolts and keep using them. To me the sear is the throw away part but your mileage may vary as they say. Undoubtedly Sam at PS has seen a lot more so go with his recommendation if that gives you peace of mind. In the end you have to monitor your gun (any gun) for wear; when you clean it is a great time to do that.

I do HIGHLY recommend the Lage safety. The OEM internal piece is die cast aluminum or zinc and is a POS. The external safety tab is tiny and not so easy to manipulate.

Richard is right about wimpy loads. I had a run on with light bullets and lighter powder charges in my .380. There was just enough energy to cycle the bolt far enough back to strip and fire the next round but not push it back far enough to catch the sear.
The previous owner installed the Lage internal and external safety already so good to go there.

Anyways once the form 4 clears to dealer I’ll send to Sam at PS to inspect, repair and recoat it just to be on the safe side. Probably a good practice anyway on a transferable of unknown round count.
 

Generalzip

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Do most you guys Parkerize or cerakote? I’d imagine cerakote might make the tolerances a little tighter and possibly add some publicity? Or something even more exotic like DLC or whatever
 
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MitchWerbellsGhost87

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Do most you guys Parker’s or cerakote? I’d imagine cerakote might make the tolerances a little tighter and possibly add some publicity? Or something even more exotic like DLC or whatever
These guns should be parkerized but I have heard cerakote is suitable as it’s very thin. I have used Duracoat with an airbrush on the exterior components but not on any moving parts. The originals were done in zinc or manganese phosphate. SWD was particularly proud of their finishes and sold their “famous” bluing salts and phosphate solution out of their catalog. The SWD guns used a pre-black dip prior to the park job, makes it much darker like a black color instead of gray. I personally love those dark black SWD m10s, like the Texas guns.

As for the bolt, it can indeed be “fixed” with a grinding implement or even a hand file. The peened sear engagement surface just has to be reshaped. you can also weld up the beat down notch and recut it, it works as a temporary solution until a suitable replacement can be secured, but this is not recommended when a brand new one can be easily obtained off the internet.. more of a “SHTF” kinda fix.
 
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skoda

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HA!!! I bought one of those SWD parkerizing kits. It worked great.

As for the bolt, I did exactly what you said on a steel and a tungsten bolt and it was easy with my little milling machine. I took very little off and they work fine. My main problem was with the Lage sear. It was kinda beat up so I rewelded it up and reground it. I have a spare but I did it just to prove to myself that it could be done. I don't know for sure but I think that the tungsten bolt did most of the damage to the sear. I tend to do longer bursts 10-30 rounds.
 

Generalzip

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HA!!! I bought one of those SWD parkerizing kits. It worked great.

As for the bolt, I did exactly what you said on a steel and a tungsten bolt and it was easy with my little milling machine. I took very little off and they work fine. My main problem was with the Lage sear. It was kinda beat up so I rewelded it up and reground it. I have a spare but I did it just to prove to myself that it could be done. I don't know for sure but I think that the tungsten bolt did most of the damage to the sear. I tend to do longer bursts 10-30 rounds.
How many rounds did it take until you needed a new sear/ bolt you found?
 

skoda

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I'd have to guess as I don't keep track of rounds fired. My guess is 15,000, possibly a few thousand more, but that would have been with both bolts and a lot of 22 (Lage system) as well. I started getting run aways after letting go of the trigger but usually just a few rounds not the rest of the magazine and it was erratic when it did happen. Since I hate taking loaded mags back home (!) I just dealt with it until I was done.

But like I said before, it depends on how often the sear is jumping up to catch the bolt (short bursts vs. mag dumps).
 

skiboatsp

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These guns should be parkerized but I have heard cerakote is suitable as it’s very thin. I have used Duracoat with an airbrush on the exterior components but not on any moving parts. The originals were done in zinc or manganese phosphate. SWD was particularly proud of their finishes and sold their “famous” bluing salts and phosphate solution out of their catalog. The SWD guns used a pre-black dip prior to the park job, makes it much darker like a black color instead of gray. I personally love those dark black SWD m10s, like the Texas guns.

As for the bolt, it can indeed be “fixed” with a grinding implement or even a hand file. The peened sear engagement surface just has to be reshaped. you can also weld up the beat down notch and recut it, it works as a temporary solution until a suitable replacement can be secured, but this is not recommended when a brand new one can be easily obtained off the internet.. more of a “SHTF” kinda fix.
Tig weld with A2 1/16 rod. Grind to original profile and its better than new. Definitely not SHTF kinda fix! Also you will not be able to file this material!
 

MitchWerbellsGhost87

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Tig weld with A2 1/16 rod. Grind to original profile and it’s better than new. Definitely not SHTF kinda fix! Also you will not be able to file this material!
No need to file if you use a grinder for the notch, it has to have a perfect right angle notch cut for sear engagement.
 

strobro32

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I'd bet if the previous owner had his finger on the trigger if that happened.

When you get it, try inserting an empty mag with the bolt back. See what happens. If the bolt drops, send it to Sam at Practical Solutions.

They are wild guns. Good luck and have fun. Welcome to the MAC forum of UziTalk! There are great people here.
 

skiboatsp

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No need to file if you use a grinder for the notch, it has to have a perfect right angle notch cut for sear engagement.
My point being welding is Not a SHTF as you stated if the repair if done correctly. Similar to welding stellite to a work surface.
 
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MitchWerbellsGhost87

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My point being welding is Not a SHTF as you stated if the repair if done correctly. Similar to welding stellite to a work surface.
But it is, because the end result is rarely properly heat treated or as hard as the original bolt and will only last a few hundred rounds before it has to be done again. There is really no reason to do a janky weld repair like that to the sear surface of the bolt when a brand new bolt is available for 200 bucks. Maybe if you are a master of your craft with welding, but for the average person this is something that can be done in a pinch to get a few hundred more rounds out of the bolt and it is not a suitable replacement for a new bolt
 

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