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blank adapting the mg42/m53/mg1-3

Blanking adapting the MG42, MG3 and MG34
Blanksguy
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Re: blank adapting the mg42/m53/mg1-3

Postby Blanksguy » Sat Mar 23, 2013 11:46 am

Hi John,
Thank you for the additional information.......(This is the reason why we ask people with "Blank-Adapting-Challanges" to give us all of the information that they have (no matter how small) about their SA42 or MG42 so that we can help them sort out issues with either the gun or the Blanks.

On the cartridge-depressor-gauge from jbaum (he can correct me if I am wrong here), he makes the gauge from the 8x57mm gauge-drawing in his great translated Books that he sells. As the .308 cartridge is shorter, I believe that the gauge would be at a slightly different angle also......to direct the shorter cartridge into the chamber after the barrel is forward.
I am not aware of anyone making a .308 gauge.

On a better explaination of why this happens........
The MG42/MG3 "system" was designed to work as a "locked-breach" system that is gas-assisted at the front to push the barrel back/unlocking the rollers and propelling the bolt-assembly to the rear/buffer hard enough to hit the buffer and eject the fired case. Due to the type/small amount of powder they used in these Blanks (NOTE: DM28A2 German manufactured Blanks seem to be running about 10.3 grs. powder....slightly less than the "weak" Austrian .308 Brass-Cased Blanks.). There is less chance of this powder to build up pressure (similar to a "firecracker" going off) as some of the pressure bleeds-off out the the current BFA-Hole and around the blank as it starts to move the bolt to the rear.....not as much pressure build up.........and the reason that I suggested the smaller BFA Hole-Size.
....................We have reached the 2,000 "letter-limit" of the MG42 Board..............
I will continue with next Thread section.
Regards, RichardS in MI.
US Army, Retired.

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Re: blank adapting the mg42/m53/mg1-3

Postby Blanksguy » Sat Mar 23, 2013 12:02 pm

...continuation of previous thread-reply................

Again.....due to not enough powder/weak-blank....and unlocked bolt......you lost some of your operating pressure.
I do not have an SA42 (I have the parts to build one, just not the time) to check the operation of an "un-locked-bolt-assembly firing Blanks so I will have to "pass" on other suggestions at this time.

I have not heard of an SA42 Bolt-Assembly overrunning the disconnector.......and this is because by nature of the SA42 design (when looking at the ejection mechanism used in an SA42/MG42) it has to hit the front of the buffer-assembly to eject the fired case.......correct (?).........."unless" (and we go back to the asking for all information up-front in first question of Thread) the SA42 was newly designed (for this one SA42) to use a modified/shorter buffer-assembly (?). Again, unless you have a modified buffer-assembly....or modified-bolt-carrier that allows the entire bolt-assembly to move farther to the rear during operation (photos always help), then it has to hit and stop rearward motion at the buffer-assembly.......re-look at "your" designed SA42.
NOTE: Surplus and newly manufactured Blanks.....be they 8x57mm or 7.62x51mm are not loaded to the same pressures........do not mixed Blanks on the same belt from different manufacturers.......you will have operational "issues" and could injure yourself and others near you when firing your MG42/SA42 !!!!!!!!!!!!!!!!!!!!

As far as my next run of 2-pcs. Blank-Barrel-Assemblies........I am now in the process of moving and will not be making more until moved/set up again for the work....which may be late summer now.

Regards, RichardS in MI, USA
US Army, Retired
Blanksguy2001@chartermi.net

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Re: blank adapting the mg42/m53/mg1-3

Postby 42rocker » Sat Mar 23, 2013 9:24 pm

Richard
Good Luck with your move.

Later 42rocker

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Re: blank adapting the mg42/m53/mg1-3

Postby blckwlfny » Sun Mar 24, 2013 12:10 pm

Yes good luck with your move

Thank you for the suggestions. my first step is going to be a smaller BFA-hole

For the purpose of the thread, I will answer your question about my bolt and buffer assemblies:
The bolt carrier pic may be found here.
http://mg42.us/download/file.php?id=12471&mode=view
The internal parts i am using now are all different; consisting of a one-piece firing pin, an old-style ejector spoon and no metal inner sleeve for the spoon to ride on.

The bolt carrier contacts the buffer slightly FORWARD of the point in an unmodified, full auto'42
This is because, although the buffer is a normal legnth, yugo buffer assembly , it in fact sets about 1/8" further FORWARD than an orginal thanks to a modifcation by GordieK

I also looked into the possibility of a round being able to eject without contacting the disconnector. Being at a disadvantage because of not having the S/A'42 in front of you, I figure id post that discovery as well:
It seems that on its backward travel, the bolt will fully cock the hammer long before approaching the buffer. I dont see how it would be possible to even contact the plunger, much les eject the casing without having cocked the hammer first. (...if im missing something , i hope that someone can correct me here)
Thanks Again John
Thanks

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Re: blank adapting the mg42/m53/mg1-3

Postby blckwlfny » Thu Mar 28, 2013 8:42 am

UPDATE:
ok I dropped the BFA hole to .125 and the gun is running much smoother. the seemingly random stops before, i noticed were when the gun was pointed downward. Presumeably, this would be the hardest position for the gun as the gas pressure has to lift the entire weight of the bolt. dropping to 0.125 seems to have cleared that up. It is still double feeding (failure to eject) every 15-20 rounds i am thinking this may be due to the belt hanging up Juuuuust a little.
...some of the links were holding the round a little loosely, but that wouldnt cause a double feed....RIGHT???
im going to try dropping the bfa hole a little more.
stay tuned.... :cross:

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Re: blank adapting the mg42/m53/mg1-3

Postby blckwlfny » Mon Apr 01, 2013 6:23 pm

dropped the hole down to .1160
....damn good recoil....spent casings fly out with force....STILL it double feeds at random points
....two questions:
1) how do i know when too much restriction is too much?
and
2) could the spring occasionally be hanging up on the buffer?

Blanksguy
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Re: blank adapting the mg42/m53/mg1-3

Postby Blanksguy » Mon Apr 01, 2013 6:54 pm

Hi John,
Thank you for the replies.......and I will try to answer your questions:
1: As you are the one who adjusts the BFA Hole-Size.....for operation......you set it up for "Blanks" as you would adjust the Booster-Cup/"Nozzle" Hole-Size for operation with live ammo. IE: You start large and work down in smaller increments until it just works.......then, because you started with a clean/lubricated system, you decrease the hole-size by .005"-.010" more so that the weapon will operate reliably when dirty.

2: Only you could tell is the recoil-spring was hanging up on the Buffer-assembly.......is it catching on a burr or broken-part (?).....or does the recoil-spring have a broken strand within the coil (?)....these are checks that the operator does prior to firing.....and which you have told us that your weapon was checked, clean, and lubricated......that all is good with your parts .....correct (?).

3: I can only go by the information that you have submitted......if you give me incomplete information......I can only give you guesses as to what is wrong. I won't go into all of the "checks"......jbaun has great translated-booklets for that ........so ideas would be the removal of the dust-cover on the ejection-opening to see if it is bouncing back tring to close and not allowing the fired cases to be ejected.........(?)
Another would be to try a new extractor, with new extractor-spring after you clean the bolt-head as either may be marginally worn-out....along with a new ejector-rod and "spoon" that operates the ejector-rod as these may have a worn-spot and act up every now and then.

Regards, RichardS in MI.
US Army, Retired
Blanksguy2001@chartermi.net

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Re: blank adapting the mg42/m53/mg1-3

Postby blckwlfny » Tue Apr 02, 2013 12:33 pm

Thank you for the replies.......and I will try to answer your questions:
1: As you are the one who adjusts the BFA Hole-Size.....for operation......you set it up for "Blanks" as you would adjust the Booster-Cup/"Nozzle" Hole-Size for operation with live ammo. IE: You start large and work down in smaller increments until it just works.......then, because you started with a clean/lubricated system, you decrease the hole-size by .005"-.010" more so that the weapon will operate reliably when dirty.

Thank you. Ill do that


2: Only you could tell is the recoil-spring was hanging up on the Buffer-assembly.......is it catching on a burr or broken-part (?).....or does the recoil-spring have a broken strand within the coil (?)....these are checks that the operator does prior to firing.....and which you have told us that your weapon was checked, clean, and lubricated......that all is good with your parts .....correct (?).

When it is cycled by hand, it moves fine. The system is clean and works fine under live ammo. I was just wondering if the vibration caused by the gun functioning has ever been shown to cause a hang up with blanks as there is some "wobble factor" in these guns.

thank you again
John

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Re: blank adapting the mg42/m53/mg1-3

Postby blckwlfny » Mon Apr 08, 2013 5:17 pm

UPDATE:
When claening the gun, I had unintentionally moved the buffer back to its original position.
I returned it to its working position as suggested by gordie K years ago. It now sits 1/8 "to 3/16" further forward than its stock position. This was done by unscrewing the buffer bolt slightly and placing spacing washers in the gap left down by the stock. As the buffer bolt is no longer pinned, I used locktite to keep it in place.
It went through the green plastic (DAG) german rounds without a problem so far.
BFA is 0.120"
I have had no problems caused by removing the rollers FOR BLANKS ONLY so far
i am taking it to an event this weekend :cross:

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Re: blank adapting the mg42/m53/mg1-3

Postby Blanksguy » Mon Apr 08, 2013 7:13 pm

John,
Alright...........sounds like you now have this issue sorted out.

On a side-note......this is (again) another reason why we ask for all information about an MG42 and/or SA42 that is having "challanges" when firing Blanks. Had we known about the change to the "buffer-length" earlier, we could possibly made short-work of correcting this challange for you. This now sounds more like the recoil-spring was having an issue of "coil-bind" and not allowing full hitting of the ejector-parts to knock the fired Blank off of the bolt-face.

I am glad that the gun is now working for you with the weaker .308 German Plastic-Blanks.
Please give us a "follow-up-report" on how things went as to firing out in the field.....and the final BFA Hole-Size that you ended up using.

Best regards, RichardS in MI.
US Army, Retired
Blanksguy2001@chartermi.net

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Re: blank adapting the mg42/m53/mg1-3

Postby blckwlfny » Mon Apr 15, 2013 10:56 am

After action report
The gun was functioning well, but double fed every 20-25 rounds. thinking that this was a short cycling issue, I decreased the BFA hole one step at a time to .120 and then .116 the problem got worse (every 3 rounds).
It seems that the extractor was tearing the backs off of the plastic cases during the extraction process.
I then went one step op from the original .120 to a .125 BFA hole and the gun double fed the first round with an INTACT case
replaced BFA hole back to .120 and moved buffer forward 1/4" . this resulted in a double feed with a ruptured case every belt or so.
My assumption here is that too much power recycled to the action is causing the extractor to rupture the cases, but what was interesting tis that the ruptured cases did not remain in battery EVER.
Now im stumped....I cant shorten the buffer any more because the case will sit too far forward and wont clear the ejection port.
I cant open the bfa any more because it will short cycle

suggestions??

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Re: blank adapting the mg42/m53/mg1-3

Postby blckwlfny » Mon Apr 15, 2013 10:56 am

After action report
The gun was functioning well, but double fed every 20-25 rounds. thinking that this was a short cycling issue, I decreased the BFA hole one step at a time to .120 and then .116 the problem got worse (every 3 rounds).
It seems that the extractor was tearing the backs off of the plastic cases during the extraction process.
I then went one step op from the original .120 to a .125 BFA hole and the gun double fed the first round with an INTACT case
replaced BFA hole back to .120 and moved buffer forward 1/4" . this resulted in a double feed with a ruptured case every belt or so.
My assumption here is that too much power recycled to the action is causing the extractor to rupture the cases, but what was interesting tis that the ruptured cases did not remain in battery EVER.
Now im stumped....I cant shorten the buffer any more because the case will sit too far forward and wont clear the ejection port.
I cant open the bfa any more because it will short cycle

suggestions??

sokerivatsa
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Re: blank adapting the mg42/m53/mg1-3

Postby sokerivatsa » Sat Jul 27, 2013 6:27 am

I am firing with a FA MG42, 2 piece .308 barrel. I don't know my BFA hole but I have made some smaller ones to test. I use the green plastic blanks.

I don't use Rollers and it does a occasional 5-10 rounds if I fire it in short bursts with small intervals without jams. If I proceed to a longer burst, say 20 rounds it will double feed. In 2 weeks I will try another BFA hole and write a after action report.

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Re: blank adapting the mg42/m53/mg1-3

Postby blckwlfny » Sun Jul 28, 2013 9:31 am

unless yours is a wiselite, this should work:
the green plastic blanks have a significantly variable powder load, so while one round works great, the next may short cycle and double feed because the bolt doesn't hit the buffer with enough force to eject the casing. I solved this problem by placing a smaller spring within the ID of the rear buffer. this allow the ejector to make contact about 1/4 ahead of full bottoming out. and if the round is powerful enough to hit the buffer, the new spring compresses within it. I used part # 9657K315 from
McMaster.com

what find of FCG are you using?
most of my burst-fires were caused by the firing pin, not the disconnector/hammer setup, I solved the problem with a 1-piece firing pin and spring from BRP

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Re: blank adapting the mg42/m53/mg1-3

Postby 42rocker » Sun Jul 28, 2013 2:52 pm

If I understand sokerivatsa correctly then he is running a full auto original mg42 style weapon. Also in Finland, correct, sokerivatsa??
What I don't understand is the no - roller part, sokerivatsa could you share a little more on than?

Later 42rocker

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Re: blank adapting the mg42/m53/mg1-3

Postby sokerivatsa » Tue Jul 30, 2013 12:38 pm

I am running a Full auto original mg42, the barrel has been threaded and it has a nut in the end to build up pressure. It is a 2 piece barrel. I am Dutch.

I use the Rollers for shooting brass " austrian " blanks and I take out the rollers so it works on the cheaper plastic blanks.

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Re: blank adapting the mg42/m53/mg1-3

Postby 42rocker » Tue Jul 30, 2013 10:56 pm

Sorry, I'm not used to the idea of removing rollers. These are the rollers that are in the bolt head? Interesting.

Later 42rocker

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Re: blank adapting the mg42/m53/mg1-3

Postby sokerivatsa » Fri Aug 09, 2013 6:50 am

Here it is firing with the german plastic ammo. Without the rollers. This weekend I'm trying out different holes in the barrel.

http://www.youtube.com/watch?v=Pf5otHNCl54

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Re: blank adapting the mg42/m53/mg1-3

Postby blckwlfny » Fri Aug 09, 2013 8:37 am

Look further up in the post
...and y'all thought I was crazy when I tried it. ;)

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Re: blank adapting the mg42/m53/mg1-3

Postby sokerivatsa » Mon Aug 12, 2013 6:23 am

It is working on plastic blanks, I reinserted the rollers and inserted a 3,5mm hole in a nut in the barrel. Still it has occasional stovepipes. Whenever I pull back the bolt the empty casing folds between the bolt and the cocking handle. You stated that making the round ejecting earlier on makes a difference. I tried this, but can you please explain this to me more?

Another possibility to make the casing not fold underneath the bolt, shortening the left end on part #4 on the picture below?
http://i7.photobucket.com/albums/y270/d ... mbered.jpg


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