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My M53/MG42 is almost there

4K views 45 replies 7 participants last post by  RetVet 
#1 ·
The last major task I have is riveting the camming piece into position. The receiver otherwise is complete with grip mods done/installed and working fine. A few pesky problems to diagnose though.....

1. I can't manually pull the bolt back far enough with the cocking handle to eject a cartridge. The raised tab on the rear of the ratchet plate prevents the handle from going back far enough.....about 3/16th" shy. Ratchet plate installed where it needs to be less the tip of the cocking handle protrude in the ejection port. I think I simply ground off too much on the tip of the cocking handle when I notched it where it interacts with the tab on bolt carrier. Easy fix.

2. Getting the bolt back past the camming piece at the point of unlocking the bolt/barrel is now a bear. It was working fine after welding the receiver halves, so I'm confused as to what's causing the problem now.

-Barrel slides back and forth freely without binding under pressure from recuperator.
-Barrel installs and the door closes smoothly.
-No apparent sharp corners or obstructions noted in transition between camming piece ramps and the rails.
-At times I can hear the bolt disengage the barrel and the barrel return forward, but the bolt still resists being pulled to the rear.
-Tried several different bolt head and barrel combinations, no diff. All this with the top cover and feed tray removed.
 
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#3 ·
"At times" the bolt releases. Definitely on boad with Gunter - try that.

If you remove everything BUT the bolt and barrel, does the same action occur? Remove the muzzle brake and press on the tip of the barrel to unlock it from the recuperator. Then add items back one by one to see if you can get it to repeat the binding.

I found my FCG housing had to be cut down more than I had expected to ensure there was enough room for everything.

HTH
 
#4 ·
I'll pull the FCG housing off tonight and give that a try first then do the step by step thing with one component at a time.
 
#5 ·
if it is binding at the very beginning, it is probly the cocking handle binding or it is causing the bolt to bind by forcing it to the side. if the portion of the cocking handle has a reverse angle on it where it engages the stud on the bolt it will shif it to the side and bind on the receiver.
 
#6 ·
By reverse angle do you mean causing the bolt to shift left or right? I believe mine may be pulling a tad to the right.
 
#7 ·
another thing (although Pirate is almost always right!) is your bolt could be catching on one of the rails...

i had to shim one side of my rails out to get it "even" with the path in the barrel and pull the other side in really good with the rivet....

you may wanna check there.
 
#9 ·
Progress made!

I added some extra steel to the cocking handle tip to aid in pulling the bolt assembly far enough to the rear to engage the ejector. Also altered the angle slightly as pirate suggested. Cocks just fine now AND ejects my dummy cartridges.:woot:

Cycled a few more dummy rounds through. With the bolt fully forward, a belt loaded, and the top cover locked in place, there's too much drag exerted to pull the cocking handle back to chamber a cartridge. Since the original bolt and FCG design held the bolt back when not firing, I believe that's normal since a belt would normally be loaded with the bolt held to the rear. I'll need to review my notes and Folkes book again.

Still have a bit of a "shopping list" to work through before this beast goes to the range for a test drive.

-Check headspace on barrel/bolt combinations
-Check gap if any between rear of pirate's firing pin unit and the bolt inside the buffer tube (looks like there will be contact between the two)
-Rivet camming piece
-Check ejector pin travel (the brass dummy rounds I cycle and ejected by hand were dented pretty good by the pin)
-Correct rotational slop between butt stock unit and buffer unit

I've got a plan for adding a safety that uses the original safety (modified) and blocks upward motion of the trigger. Just need to pencil it out. Also a plan for installing the ejection port cover and making it functional.
 
#10 ·
when first charging the gun you need to have an empty link over the feed slot. also if there is a lot of drag check the feed tray fit.

as far as the fp goes if it is to long in the back you can trim a little off as long as it sticks out about an 1/8" with the ejector ring rearward and the fp forward.
 
#11 ·
Thanks again pirate!

I was positioning the belt ala 1919 style with a cartridge lined up. Makes sense to line up an empty given the spring pressing down from the top is so stout.

Trimming the pin a little sounds like the way to go vs. drilling a hole in that bolt. Easier too.

I'm starting to like this little welding unit now that I'm getting the hang of it. My welds joining the two receiver halves came out premo with very good penetration all around and no pores. I do seem to be going through the Argon fast though. I might need to go with a bigger tank.
 
#12 ·
glad to see you are getting near the end!! as far as the argon goes, check your regulator, some of the cheap ones increase the flow rate as the bottle pressure decreases. I use ended up getting a better one with a ball in a tube flow meter.
once you learn how to use that little tig you will wonder how you ever lived without it!!!

the 42 is different as you are starting with a closed bolt and as you pull it to the rear the feed lever advances the belt. if there is a ctg in place the feed mechanism drags.
 
#13 ·
Closer to completion, but still a bug to work out.......weak hammer strikes. I removed just the minimum of material from the FAL hammer so it would clear the bolt extension. Installed a new spring in hammer spring assembly. All well lubed.

Out of about 15 rounds of Romanian chambered only 3 rounds hit hard enough to fire. The indentations on the primers have been vary inconsistent varying from what looked like fairly solid hits to so weak they barely left an impression.

I'll have to fiddle with things a bit more to isolate the problem. Perhaps the tip of the hammer is grazing the recoil spring and causing drag or there's something amiss in the striker assembly in the bolt. It also looks like the hammer is hitting the striker assembly towards the top end of the hammer, so perhaps some energy is being lost there as opposed to hitting it more in the middle at more of a right angle.

On the positive side I finished a set of oak grip panels that match nicely with the teak wood stock on my kit. They took all day to make! I also finished my mods to the original safety making it fully functional to work with the FAL FCG parts.

Pictures coming tomorrow.
 
#14 ·
Hey bub good to know you've got it down to the fine tuning stage...

couple of things to look for:

the recoil spring hitting the hammer is first.. this was an issue

next: is your hammer draggin or touching in the top of the bolt extension?

then check to make sure that your FCG is not too tight in the gripstick...

Pirate had to help me in this area.... if your spring is out of the FCG and you turn it upside down will the hammer just fall thru its path??

if not then you have too much drag/bind...

last thing: are you at a 90* or more angle when you get your contact with the FP? it really needs to be at least at the 90* mark or farther forward in its swing path.

Romanina is running like a raped ape in mine but the turkish stuff seems a bit iffy.
 
#15 ·
the recoil spring hitting the hammer is first.. this was an issue

I think I'm ok there, but I'll check again

next: is your hammer draggin or touching in the top of the bolt extension?

AOK There. nothing touching

then check to make sure that your FCG is not too tight in the gripstick...

I'll check that again. Seemed loose enough, but I didn't turn it upside down to see if it would swing freely.

lLast thing: are you at a 90* or more angle when you get your contact with the FP? it really needs to be at least at the 90* mark or farther forward in its swing path.

I'll check that as well. It might not be hitting quite square enough. Hope that's not the problem because that means my whole grip mod is hosed and I sure hate the thought of having to cut things loose and reposition as that messes up my grips and the safety not to mention placement of the attachment ears on the receiver and my dust cover attachment mods.
 
#18 ·
then check to make sure that your FCG is not too tight in the gripstick...

I'll check that again. Seemed loose enough, but I didn't turn it upside down to see if it would swing freely.

lLast thing: are you at a 90* or more angle when you get your contact with the FP? it really needs to be at least at the 90* mark or farther forward in its swing path.

I'll check that as well. It might not be hitting quite square enough. Hope that's not the problem because that means my whole grip mod is hosed and I sure hate the thought of having to cut things loose and reposition as that messes up my grips and the safety not to mention placement of the attachment ears on the receiver and my dust cover attachment mods.
So it seems we are at relatively the same place in our builds. I have screwed the rails in as opposed to riveting at this point because I want to make sure everything functions first. I am also having light hammer strikes or so I believe. I have not chambered any rounds but visually, tactilely, and audibly things sound light or not quite right.

Here is an eye candy pick. It will mean a heck of a lot more when it goes bang! Time to go check the angel of my dangle!

 
#17 ·
I shortened the tip of the charging handle to clear the FCG parts (hammer) and added about a quarter inch to the rearward side of the tip so that when engaged with the bolt carrier, the carrier is pulled far enough to the rear to hit the buffer and allow a case to be ejected by hand cycling. I had to add some metal there because I ground off too much during the initial mods.
 
#19 ·
While I am thinking about it, I think I may have welded my receiver .060 to short. When I place the barrel in barrel gate and close it so the barrel is resting on the recuperator it over laps maybe .100-.125. It?s hard to measure in there. I can get the barrel door closed and can hear the barrel snap into place but I am positive it has a tad more resistance than it should. I have yet to disassemble the recuperator, clean, and relube grease everything which will probably help. Should I leave it be? Or cut the trunion area and reweld it?
Thoughts please.
 
#21 ·
I rechecked things a bit more last night. The hammer is hitting the striker at the point where the hammer just begins to radius back at the top rather than hitting the flat face of the hammer. It's right at that transition. I may need to reshape the face of the hammer a bit or adding metal to the top of it to build up a flatter face. Trimming the striker back more at this point will allow the hammer to swing further forward, but that would also result in it contacting the hammer closer to its top. In short, my hammer sits just a smidgen too low.

I have a few spare hammers I can check to see if one will work better than the one I currently have installed. These are all foreign made FCG parts I'm tinkering with at this point. Once I'm done debugging I'll modify a US made set to satisfy the parts count gestapo.
 
#23 ·
RV,

that was one reason i didnt finish welding my FCG brackets ntil after it all worked out...

you should stil have a small bit of play in the rear mounting spot if you didnt weld it either and this may give you enough.

you would have had to cut a mountain of hammer off to get it toooo short.

mine also hits right on that line from the front face to the next angle back, but it has plenty of whack on romanian and yugo stuff.

but ive found it doesnt really care much for the turkish stuff.
 
#24 ·
Sounds like yours is hitting the striker about where mine is. I don't think I could have positioned the whole grip assembly any higher without it being canted upward at the front. No worries, one more minor mod is no big deal at this point.

I'll polish things a bit more and apply some of that expensive lube I bought for my MG34. That stuff is slicker than slick.
 
#25 ·
I forgot to ask, but do you guys consider the modified bolt carrier and the modified grip frame as US made parts now that they've been altered so much?

With the Wise Lite receiver, hammer, trigger, sear, and home made grip panels I have 5 US parts so far.
 
#27 ·
I ended up trimming the spring on the firing pin. It seemed very stiff and about .1875 longer than it needed to be. Now when the hammer strikes, it sets the firing pin in instead of bouncing off. I hope this doesn't adversley effect any thing else. What this super duper lube?
 
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