So I've been receiving alot of requests / questions on this, and thought it would be a good "how to" or reference guide to put here for anybody wondering about this.

First I bought an Arsenal 107CR and sent the forms off to the ATF. In my wait I was trying to decide who I would have cut and crown the barrel for me. I called around and local smiths wanted anywhere from $80-$150 to do this. So I started doing research and found out that this was a pretty simple job to do oneself. In the next few weeks I bought an Arsenal 106U. This confirmed that I would do the chop-job myself cause I didn't want to spend double.

So, I bought a good hacksaw from Home Depot (and good, bi-metal blades for it too). My research told me that I'd need to file the muzzle square after the hack-job. Then once it's square(ish) the crowning tool takes care of the rest. Then just finish it off with some steel wool and some cold blue.

FYI: The 107CR and the 106U models do not require opening up the gas ports after the chop like the 107UR models do. (At least my CR didn't.)

Oh yeah... I rented the crowning tool from here. Dinzag Arms

And here's a helpful link on crowning. crowning link

Of course you all know this already, but you cannot cut the barrel below 16" until your approved tax stamp is in your hand.

107CR


106U


tools


end products
107CR


106U (I just recently re-crowned this one to get it flush)

Yeah... I didn't know if it was exactly square or not, but yes, the crowning tool makes it 100% even. It has a brass pilot guide that fits exact to the caliber and as you turn it, it takes away the necessary metal to even it out and finish it off.

I had them engraved at a local place here in the Denver metro area.

Cut it with about 1/8" barrel left sticking out (1/4" if you're feeling nervous) and and file / crown down to about 1/16 left sticking out. The angle is a bit deceiving, but they are both pretty close in terms of "barrel left sticking out".

And no, it doesn't really matter if you have a little more or less sticking out than I have. The only thing that you'd have to worry about is if you're using the Bulgy 4 piece hider (like the one on my 106), cause if you have too much barrel sticking out, it will come in contact with the inside of the hider and won't allow it to screw on all the way. Also, I believe you need a little gap in there between the barrel and the inside of that device, to help it function as intended. (Anybody please correct me if I'm wrong... I'm not an expert, just a regular dude who chopped his barrels and they work perfect, so I'm spreading my info.)

I'd say 1/16" is about perfect for both applications.

Where can I buy one of those crowning tools and how much are they?

Very nice! So, are these forms available on the ATF website? What forms are required?

Thank you!

Bud

Originally Posted By Bachelor_of_Science: Very nice! So, are these forms available on the ATF website? What forms are required? Thank you! Bud

It's a Form 1 (5320.1), an "Application to Make and Register a Firearm".

And actually I just looked on their website where you download the forms and this one is not available. They state if you want a hard copy to contact them directly.
www.atf.gov/forms/5000.htm#firearms

FYI: The 107CR and the 106U models do not require opening up the gas ports after the chop like the 107UR models do. (At least my CR didn't.)

Do all 107URs require a larger port? How much would that usually run, like for the total job?

micah360 could a person cut down the barrel to 314mm/12.36" and then crown it and permanently attach a 110.74mm/4.36" break and not have to do a SBR ATF Form? The overall length with the break welded would be 424.74mm/16.72". The reason I ask is I would like to convert a Saiga 16" to a 107CR clone.

micah great write up! Just to let you know your link to the "crowning how to" seems to not be working.

ETA: This one seems to work www.dinzagarms.com/downloads/crowning.pdf

I'm getting ready to do this on my 107CR. I was thinking about using the existing thread protector as a guide when I cut. Just leave it on, but unscrew it a bit to give me some barrel length outside of the FSGB. Good or bad idea? I would think this would help me keep the cut at 90 degrees. Also, are the pictures you have at the top of the thread with the crown already cut?

Awesome Post!! Thanks a lot!!

Gentlemen,
The pics up above in the Op's first post are "X's" and not working for me now, in typical, .gov style fashion. Not sure if it's a temporary thing, or if they need to be updated perhaps?? I would really like to see them, if anyone can help????
Anyhow, I have only recently purchased my first AK's, and I only own milled Arsenals.
I would have thought that cutting down and SBR'ing a bbl with a hacksaw (or any other tool/method I suppose), the risk of somehow harming the chrome lining would be an issue, no?
Is the chrome lining NOT an issue when cutting down a CL'd bbl?

I realize AK's are not benchrest rifles, but I sure wish you guys would gather CAREFUL grouping data of your bbl, BOTH before AND after the bbl has been cut down.
I once knew a very skilled bbl maker, (I knew a couple of these guys actually), and they always told me that once you mess with a bbl in any way, you run a high risk of affecting the accuracy negatively.
As I said, I realize this is an AK, and an Krink at that, so accuracy isn't the biggest concern. I also should say that my old bbl making buddies from years past, also told me that this generally is a MAJOR concern, only when the bbl is reprofiled, and simply cutting a bbl down isn't a VERY high risk.
However, I would really like to see/hear some accuracy reports, BOTH before AND after the bbl is cut down.
SO, if anyone else is planning this procedure, please record some accuracy info, IF it's not too much to ask guys.
To the OP: Great thread here! I sure do appreciate you posting this info. I had considered doing a bbl cut down myself using a hacksaw in the past, but I never was very certain it I would be able to get the muzzle/crown nice and SQUARE, without the use of a lathe. I never should have sold my lathe. Biggest regret I ever had...

Micah, I have a 106CR that I'm thinking of doing an SBR, and wondered if you knew if a standard AK74 brake would work on the CR? Thnaks!