DIY AK barrel threading and crowning for SBR

[DapperDan]

Have a question for some of the ak builders here on the forum. I’m looking into buying a rifle kit that Atlantic firearms is currently selling and converting it into an sbr. The rifle comes fully assembled minus furniture and I’d like to not have to remove the barrel to do the chop, thread and crown. The kit has a gas block/front sight combo so it’s kind of asking to SBR’d. I have access to machine tools for cutting the barrel, and squaring up the end is no issue. What tools would you recommend for resizing the barrel OD so it can be threaded? Thinking of going with a standard sized thread over the 14x1LH for more options of muzzle devices. Any input, recommendations, suggestions would be greatly appreciated. I’ve watched a few different YouTube videos and have got the basics down of what all ill
need but would like to have some first hand recommendations. Thanks

 

[snorko]

Those DIY kits have Draco style gas systems so cutting it back to12 inches or so should be straight forward. I also recently had a 5.56x45mm AK rebarreled and threaded 1/2×28. Trying it yourself is cool but if you plan to use a suppressor I would have a pro handle it.

I saw those assembled kits on sale and they are tempting as I have a few sets of furniture laying around.

 

[duffman0286]

If you dont want to have the barrel pulled and threaded then this all comes down to what the barrels Outside diameter is. You will need calipers or a micrometer to read this. For 14x1 which i would recommend first (its thicker and if you mess up you can always go 1/2x28).

14x1 requires a barrel OD of .5431 min to .5501 max

1/2x28 is .4924min to a max of .4989

Snorko is right if you plan to suppress your threading done in this manner may not be concentric to the bore which could lead to baffle strikes. Not as much of a issue with muzzle devices.

Crowning can be achieved a number of different ways brass lap tools are available on ebay and many have used brass screws in a drill with lapping compound with with good results (myself included) but lets not lie to ourselves ether lathe is always the best tool method.

I hope that helps some!

 

[DapperDan]

Thanks for the comments guys, not sure if you’re aware of the style of tools used to cut down the OD and the threads, but both of them use a pilot that fits down into the barrel. I know it’s not as precise as threading the barrel on a lathe, which is something I can do as I’m a machinist by trade. I just didn’t know if any of the guys on here that build aks had done it this way and what their results are. I’ve never had to remove or install a barrel on an ak, the DIY tools are very simple to use and from what I’ve read online produce good results

 

[duffman0286]

I had great results on a Mak90 debanning using TAT (thread alignment tool) and die 14x1 LH... I was lucky and did not need to remove any material on the barrel to reduce the OD. Yes im aware they make cutter to manually reduce OD's but i can say ive seen one used on a gun barrel before but i would be interested in seeing the results.

Me personally i find it quicker and easier to pop out the barrels and turn on a lathe (but i have those tools and ive built quite a few AK's) but i understand why one wouldn't want to remove it and im trying to respect that reasoning.

 

[AdamP123]

Thanks for the comments guys, not sure if you’re aware of the style of tools used to cut down the OD and the threads, but both of them use a pilot that fits down into the barrel. I know it’s not as precise as threading the barrel on a lathe, which is something I can do as I’m a machinist by trade. I just didn’t know if any of the guys on here that build aks had done it this way and what their results are. I’ve never had to remove or install a barrel on an ak, the DIY tools are very simple to use and from what I’ve read online produce good results

What is the current OD where you will plan to thread and what thread pitch are you considering? I do not see that you mentioned this. Personally, I would not mess with it unless I could put it on a lathe as a hand tool would easily screw up your barrel concentricity. The barrel diameter should already be alright for M14x1LH. There are tons of options in that thread

This link is a good resource for this thread: https://www.cncwarrior.com/v/vspfiles/Barrel_Threading.pdf

As far as tools go, I'd recommend a Manson crowning tool and a CNC Warrior threading kit with your die of choice. I have nothing for ya in regards to tools that reduce the OD of the barrel.

 

[DapperDan]

Rifle finally arrived last week. Seems to be pretty good quality. Test fitted some furniture I refinished on it just to see how it’ll look. Going to do some testing with it later this week and make my decision to move forward with the form 1. After getting a few quotes I think I’m just going to have the work done, $150 seems pretty reasonable for the chop and thread job.

 

[duffman0286]

At that price with all the projects i have going on even i would send it in! Good looking firearm BTW!