Threading a MAC-90 barrel

[Hodgie]

I have had a Mac-90 for some time now that I put back into it's proper form furniture wise. I do not really enjoy shooting it much because of the muzzle rise and recoil due to lack of recoil. I have threaded barrels before on other rifles by hand but never an AK with the FSB on in and the fact that it was once threaded and machined down due to Clinton's failed assault weapons ban makes me Leary of doing it myself and running the risk of not having enough material and screwing it up.

Anyone gone through this process before or know a good AK smith or builder who would do it for a fair price?

[retcolusa]

Does Ben Murray do barrel threading??

[AKBLUE]

Start here and read about the diameters, options and tools etc.

https://www.cncwarrior.com/v/vspfiles/Barrel_Threading.pdf

[Hodgie]

Start here and read about the diameters, options and tools etc.

https://www.cncwarrior.com/v/vspfiles/Barrel_Threading.pdf

Thank You for that.

From everything I read it's highly suggested that I remove the FSB in order to thread the barrel which is something I did not want to do since I do not have a press. Do you think it can be correctly done without removal and if it could can I just use a crush washer to time the new break like an AR since there will be no locking detent?

[lonewolf]

Back in the mid 90's there was some company making threaded ends, that specifically made to fit on MAK's that had their threads removed, that you were able to lock tit in on your nutured threads...

There was also funky ones that were made for sks's but it was long to pin into the front site base, just like some of the muzzle brakes and Flash suppressors...

UPDATE!!!!!

http://www.usmachinegun.com/products.php?cat=78

[AKBLUE]

Start here and read about the diameters, options and tools etc.

https://www.cncwarrior.com/v/vspfiles/Barrel_Threading.pdf

Thank You for that.

From everything I read it's highly suggested that I remove the FSB in order to thread the barrel which is something I did not want to do since I do not have a press. Do you think it can be correctly done without removal and if it could can I just use a crush washer to time the new break like an AR since there will be no locking detent?

It can be done without removing the FSB as long as the die has the threading cutter that runs all the way to the edge on one side of the die.  The FSB can be drilled for the plunger if not currently. Remove the front pin and drill or simply install the spring & plunger.
What diameter is the barrel at the muzzle to start with?

[Hodgie]

Start here and read about the diameters, options and tools etc.

https://www.cncwarrior.com/v/vspfiles/Barrel_Threading.pdf

Thank You for that.

From everything I read it's highly suggested that I remove the FSB in order to thread the barrel which is something I did not want to do since I do not have a press. Do you think it can be correctly done without removal and if it could can I just use a crush washer to time the new break like an AR since there will be no locking detent?

It can be done without removing the FSB as long as the die has the threading cutter that runs all the way to the edge on one side of the die.  The FSB can be drilled for the plunger if not currently. Remove the front pin and drill or simply install the spring & plunger.
What diameter is the barrel at the muzzle to start with?

I haven't measured yet but plan to this weekend once I get it I will update the thread.

Thanks for the help and info.

[Hodgie]

Measured the diameter of the muzzle before I started I made sure my digital calipers were correctly calibrated in inches. All measurements were taken in MM.

Here's a few shots of what the muzzle and crown look like.



I took three horizontal readings front, center and rear right before the barrel steps up.




I also took 3 vertical readings and the numbers were a bit different.

[AKBLUE]

Based on the setback of the FSB and the shoulder that exists in the front of the FSB you will need a crush washer etc., to fill that gap.  If you do fill the FSB for a plunger you can notch the washer etc.
The .5488" barrel diameter is good to go for 14mm x 1 pitch threading.

[Hodgie]

Based on the setback of the FSB and the shoulder that exists in the front of the FSB you will need a crush washer etc., to fill that gap.  If you do fill the FSB for a plunger you can notch the washer etc.
The .5488" barrel diameter is good to go for 14mm x 1 pitch threading.

Thank You for all your help it's appreciated!
Unfortunately the threading kit is out of stock that CNC warrior offers so I am going to have to wait and keep checking back or search for another.

http://www.cncwarrior.com/AK-47-14x1LH-Barrel-Threading-Kit-p/25145.htm

[Meshuggah12]

Im a big mak90 fan and own several so  Ill be keeping an eye on your project Hodgie.

Do you plan on adding the plunger to the FSB?

[Hodgie]

As long as the crush washer will allow me to tighten it down and time the comp correctly I most likely will not. I came across a new production post ban FSB with the spike bayonet that would be great however it was over $200.00 so while I may go that route one day it's not going to be right now.

[lonewolf]

I put a slant brake on my NHM-91, which left a gap between the brake and front post, still tight after 10+ years of shooting it.....