Airsoft Canada - View Single Post - Going to "tackle" a unfamiliar gun (A&K Mk43) with unsure issue

ccyg8774 · November 22nd, 2013, 18:28

The gun in question is a A&K Mk43 with the "brick" gearbox. I have some experiences on V2, V3, V7 (G&G, not TM) and RS T1, T3, but I don't have any experience on A&K Mk43 or M60VN or any similar LMGs.
The major issue with that gun is it fires at about 260 FPS.
The minor issues include the existance of the microswitch and the wiring to the box magazine being wrong. But I will worry about those later.
I did tried to take down the front end once to look at the hop-up chamber, which is known to have issues in Mk43, but can't really tell if there is a problem in the nozzle-rubber sealing by just looking. The only thing I got from that attempt is finding out that the hop-up rubber looks like an aftermarket one, probably a flat-hop.

My plan for the next few steps includes:

1. Swap to a spring with known FPS and chrono again, so I know how much is the FPS drop. (It has quick spring changing so this do not involves opening the gearbox... yet. )

2. Check if the piston is moving all the way forward. (if the travel of the piston is too long and the spring being too short).

3. Open the gearbox, shim if necessary.

4. Take out the piston, cylinder, and nozzle. Check if there is a leak between the piston head to the cylinder, the cylinder and the cylinder head, the cylinder head and the nozzle. Change piston head O-ring, the nozzle, or teflon wrap the cylinder head if necessary. If the problem is with the nozzle, I heard the nozzle for A&K MASADA will work as the length is close (is that true?), if not then I guess I will have to make one.

4.1. Check the strength of the tappet plate return spring. (Thanks to Windows)

5. Dissamble and reinstall the hop-up chamber, check if the rubber and nub being installed correctly, teflon wrap the rubber-barrel seal if necessary.

6. If all of that don't work... Guess I will do one of the following and hopefully improve the nozzle to rubber seal. (Seems to be the only place left.)
a) If I am using a custom made nozzle: Making a slightly longer nozzle.
b) If I am using a MASADA nozzle: I will file the tappet plate to make the nozzle extent more forward (I assume I can do that to the M60 gearbox like to a V2 or a V3? ), only a little bit each time.

7. (Only if it is working properly) I will deal with the electronic part.

What do you think? Any thoughts? Suggestions? Things I should pay attention or look closely when working on a Mk43? Do you think this is a good sequence to check (I'm trying to start from things that are easy to check and fix)? Any additional things you think I should check?

Thanks.

November 22nd, 2013, 18:28	#1
ccyg8774 Trader rating Join Date: Jun 2012 Location: Brampton, ON	Going to "tackle" a unfamiliar gun (A&K Mk43) with unsure issue - Looking for help and advice The gun in question is a A&K Mk43 with the "brick" gearbox. I have some experiences on V2, V3, V7 (G&G, not TM) and RS T1, T3, but I don't have any experience on A&K Mk43 or M60VN or any similar LMGs. The major issue with that gun is it fires at about 260 FPS. The minor issues include the existance of the microswitch and the wiring to the box magazine being wrong. But I will worry about those later. I did tried to take down the front end once to look at the hop-up chamber, which is known to have issues in Mk43, but can't really tell if there is a problem in the nozzle-rubber sealing by just looking. The only thing I got from that attempt is finding out that the hop-up rubber looks like an aftermarket one, probably a flat-hop. My plan for the next few steps includes: 1. Swap to a spring with known FPS and chrono again, so I know how much is the FPS drop. (It has quick spring changing so this do not involves opening the gearbox... yet. ) 2. Check if the piston is moving all the way forward. (if the travel of the piston is too long and the spring being too short). 3. Open the gearbox, shim if necessary. 4. Take out the piston, cylinder, and nozzle. Check if there is a leak between the piston head to the cylinder, the cylinder and the cylinder head, the cylinder head and the nozzle. Change piston head O-ring, the nozzle, or teflon wrap the cylinder head if necessary. If the problem is with the nozzle, I heard the nozzle for A&K MASADA will work as the length is close (is that true?), if not then I guess I will have to make one. 4.1. Check the strength of the tappet plate return spring. (Thanks to Windows) 5. Dissamble and reinstall the hop-up chamber, check if the rubber and nub being installed correctly, teflon wrap the rubber-barrel seal if necessary. 6. If all of that don't work... Guess I will do one of the following and hopefully improve the nozzle to rubber seal. (Seems to be the only place left.) a) If I am using a custom made nozzle: Making a slightly longer nozzle. b) If I am using a MASADA nozzle: I will file the tappet plate to make the nozzle extent more forward (I assume I can do that to the M60 gearbox like to a V2 or a V3? ), only a little bit each time. 7. (Only if it is working properly) I will deal with the electronic part. What do you think? Any thoughts? Suggestions? Things I should pay attention or look closely when working on a Mk43? Do you think this is a good sequence to check (I'm trying to start from things that are easy to check and fix)? Any additional things you think I should check? Thanks. __________________ Last edited by ccyg8774; November 22nd, 2013 at 22:54..