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CO, USA
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Posted: 4/2/2008 12:44:35 PM EDT
[Last Edit: micah360]
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) 
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Posted: 4/2/2008 11:46:07 PM EDT
[Last Edit: RetroRevolver77]
[#1]
Great topic. How did you know your muzzle was 90 degrees after you filed it? If it were off slightly would the cutter/crowning tool kind of make it even? Finally who engraved your recievers with your info?
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CO, USA
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Posted: 4/3/2008 12:40:39 AM EDT
[Last Edit: micah360]
[#2]
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. |
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TX, USA
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Posted: 4/3/2008 9:47:57 AM EDT
[#3]
With regard to the 107CR, how much of the barrel is left--past the nut--after you make the cut? In other words, does it matter how far the barrel extends into the flash-hider/booster? It looks as though you left more barrel on the 107 than you did on the 106 . . . .
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CO, USA
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Posted: 4/3/2008 10:35:36 AM EDT
[Last Edit: micah360]
[#4]
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. |
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Posted: 4/3/2008 7:26:30 PM EDT
[#5]
great thread!
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NV, USA
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Posted: 4/6/2008 7:48:24 PM EDT
[#6]
Where can I buy one of those crowning tools and how much are they?
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CO, USA
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Posted: 4/7/2008 5:21:19 PM EDT
[#7]
Not 100% sure...try online at Brownell's or Midway USA. |
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Posted: 4/8/2008 2:33:59 AM EDT
[#8]
Very nice!
 So, are these forms available on the ATF website? What forms are required? Thank you! Bud |
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VA, USA
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Posted: 4/8/2008 9:50:34 AM EDT
[#9]
Michah360- great info, thanks for sharing.
What kind of groups will your 107CR shoot before and after the shortening? Any idea on reduction in muzzle velocity? Thanks! |
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CO, USA
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Posted: 4/8/2008 4:15:01 PM EDT
[#10]
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 |
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CO, USA
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Posted: 4/8/2008 4:23:01 PM EDT
[Last Edit: micah360]
[#11]
you're welcome... I really doubt much accuracy was lost in the shortening (I mean only 3.75" was chopped off). I'm not really sure on groups... I only shot a couple mags thru it for function check before the barrel chop at soda cans in the mountains. I can say that after the chop, I was hitting torso-sized (roughly) silhouettes at 200 meters about 75% of the time (with iron sights). I have no idea on any change in velocity. |
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MO, USA
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Posted: 4/27/2008 1:20:58 PM EDT
[#12]
Do all 107URs require a larger port? How much would that usually run, like for the total job? |
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VA, USA
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Posted: 6/1/2008 2:25:27 PM EDT
[#13]
The barrel should be flush, or close to flush, with the FS/GB when cut and crowned.
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Posted: 6/26/2008 4:36:45 AM EDT
[#14]
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.
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CO, USA
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Posted: 6/26/2008 11:07:50 AM EDT
[#15]
Yes... that would work great (I would have done this if I wasn't in free state). The second break down on this linked page is the one you'd need.
www.ak-103.com/parts.html But, I don't know the legalities of doing this yourself as you will have an illegal NFA firearm in your hands in the time between cutting it and attaching the permanent break. |
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Posted: 7/1/2008 11:00:15 AM EDT
[Last Edit: decodeddiesel]
[#16]
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 |
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CO, USA
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Posted: 7/1/2008 3:23:11 PM EDT
[#17]
Thanks man... I changed it above too.
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USA
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Posted: 7/7/2008 8:38:13 AM EDT
[#18]
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?
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CO, USA
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Posted: 7/8/2008 2:55:54 PM EDT
[Last Edit: micah360]
[#19]
The crowning tool will make it square for you, so I wouldn't worry all that much about the initial cut. But, yeah... I guess that might work. And yes... the pic of the 107CR muzzle is totally complete. |
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MN, USA
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Posted: 9/30/2008 5:11:24 PM EDT
[#20]
Awesome Post!! Thanks a lot!!
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TN, USA
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Posted: 10/21/2008 1:36:41 PM EDT
[#21]
Another good quick site for ATF forms is www.titleii.com |
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Posted: 1/6/2009 9:47:28 PM EDT
[#22]
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... |
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CO, USA
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Posted: 1/9/2009 10:32:45 AM EDT
[#23]
Opps... sorry. I'll get the photos reposted asap.
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GA, USA
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Posted: 12/28/2009 11:36:04 AM EDT
[#24]
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!
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Posted: 12/28/2009 12:16:55 PM EDT
[#25]
a standard 74 break will not time properly with a CR, but you can use it.
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GA, USA
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Posted: 12/30/2009 3:13:47 AM EDT
[#26]
Hey Nictra, you seem pretty knowledgeable on this topic, and I've seen your posts in others, so here's a question for you! Working on the parts for the SBR of my 106 whilst I await the paperwork, and am trying to decide on a muzzle device. I have the long "krink" style brake that's on the gun, and I've looked at the shorter krink type. How do you think the 4 piece krink brake would work on the CR? I've looked around and Ive seen some in 7.62, but I've seen you comment that they'll work on the smaller caliber as well. Do you have a source for real Bulgy 4 piece? I've checked Cope's, Kvar, no luck. Thanks in advance!
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Posted: 12/30/2009 12:35:13 PM EDT
[#27]
tried to IM you so as not to get this thread off target, but you have it turned off.
I think the 4 piece would work great on an SBR'd CR. That's what I will probably use on mine when I do it. Try DSA for the 4 piece http://www.dsarms.com/Original-Bulgarian-762x39-Krinkov-4-Piece-Flash-Suppressor––––KR009B/productinfo/KR009B/ or keep an eye on the EE be sure you read the thread in the krink section, there are some bogus ones made out there that are being pushed as Bulgarian. |
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GA, USA
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Posted: 12/31/2009 9:02:44 AM EDT
[Last Edit: roninsan]
[#28]
I surf alot but rarely post so I don't think my IM is active. I'll call DSA and see if they have the 4pc in stock. I'm thinking I should have bought a 107CR instead........
Thanks for the help! Update: DSA is out and no idea on BO being filled. I've searched the net to no avail. Only thing I've found is the knock offs that don't even come close. Damn. 
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USA
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Posted: 1/8/2010 6:46:09 PM EDT
[#29]
Ha ha! After about a year of putting this project off, I finished it today. Dinzag's crown tool worked great! Well worth the money for the rental.
Easy DIY project. The only thing I should have done differently was to hand file more of the barrel off initially. I left about a 1/4" at first. I thought the crown tool would make easy work of that. I soon realized it would be faster/easier to take it down flush with the FGB by hand. After doing that, the crowning tool finished it off. You really can't go wrong with this. Take your time, don't rev the drill too high, and continue to use the oil. Check it out... 
107CR 107UR 
Now, if I could only remember where I put the sling at. |
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GA, USA
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Posted: 1/9/2010 6:16:49 PM EDT
[#30]
Wow 'bean, those turned out nice! I'm holding off until I find the muzzle device I want. Where'd you get the 4 piece on your 107UR? And the one on the CR? Wish I had gotten my CR in 7.62.........
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USA
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Posted: 1/10/2010 2:38:27 PM EDT
[#31]
Originally Posted By roninsan:
Wow 'bean, those turned out nice! I'm holding off until I find the muzzle device I want. Where'd you get the 4 piece on your 107UR? And the one on the CR? Wish I had gotten my CR in 7.62......... Thanks. I only did the CR. The UR was done last year at Elite Iron. I think I got the 4-piece from K-VAR...its been a while. The one on the CR was purchased at aa-ok. However, I had a rough time (high shipping costs, bad customer service, charged for items not received, took a long time to refund my account, etc) with aaok and really can't recommend you go there. I really gotta thank micah360 for the how to thread. It was a fun DIY project! |
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CO, USA
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Posted: 1/18/2010 4:08:30 PM EDT
[Last Edit: micah360]
[#32]
no problem. nice job by the way
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PA, USA
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Posted: 1/22/2010 8:37:58 AM EDT
[#33]
Question for the guys who chopped down their CR's. Does it dramatically change how the rifle handles with the barrel shortened and booster on? Is their noticeably less recoil and does it help eliminate the blast.Does it warrant the Form 1 and the waiting game for this transformation. I have a 106CR and I really want to know was it worth all the time and extra $200 in your opinion.I would really like to use the SBR variant CR in my short range practical rifle matches but the naked barrel and fake brake make it a bit heavy and blasty at the end. I wanted to get some more feedback before I go the SBR route......again! LOL These damn things end up multiplying! Thanks Dan
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USA
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Posted: 1/22/2010 7:14:40 PM EDT
[#34]
Originally Posted By 556sniper:
Question for the guys who chopped down their CR's. Does it dramatically change how the rifle handles with the barrel shortened and booster on? Is their noticeably less recoil and does it help eliminate the blast.Does it warrant the Form 1 and the waiting game for this transformation. I have a 106CR and I really want to know was it worth all the time and extra $200 in your opinion.I would really like to use the SBR variant CR in my short range practical rifle matches but the naked barrel and fake brake make it a bit heavy and blasty at the end. I wanted to get some more feedback before I go the SBR route......again! LOL These damn things end up multiplying! Thanks Dan I can't be of too much help here as I didn't shoot the CR much before cutting it down. I can tell you that the muzzle blast only increases by cutting and boosting. To SBR or not would be a personal choice. I went into the deal knowing that's what I wanted to do. I think you get more bang for your SBR buck with the UR than the CR but since I had both it wasn't a concern to me. |
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Posted: 5/24/2010 10:19:43 AM EDT
[#35]
on the 4 piece muzzle device, DSA is sold out, K-var is sold out, the only ones I can currenlty find are the joken version which is not original comblock stuff joken muzzle device
other than watching the EE and gunbroker, anyone know of another source of those? |
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USA
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Posted: 9/12/2010 6:17:20 PM EDT
[#36]
Whats the overall length of the 106 and 107 with the stock folded?
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FL, USA
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Posted: 10/23/2010 9:59:27 PM EDT
[#37]
This is an updated link to "ATF form 1".
http://www.atf.gov/forms/download/atf-f-5320-1.pdf |
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KY, USA
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Posted: 8/15/2011 9:36:47 PM EDT
[#38]
I am about to send in my forms on my 107CR.. and while looking at it I noticed that the fake brake has considerable wobble. I checked and it is turned as tight as it can go to index the pin. My concern is that after I get my forms back and I perform the bbl. job will the new brake tighten up and eliminate the slop. I know this is probably a dumb shit question but I have to ask since I am a first timer doing this mod. Thanks
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Posted: 8/15/2011 10:18:51 PM EDT
[#39]
Is anyone doing crowning tool rentals? I dont see it on Dinzigs website anymore.
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Posted: 12/31/2011 8:47:18 PM EDT
[#40]
Cutting through the chrome lining cause any difficulties?
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Posted: 1/16/2012 3:03:53 AM EDT
[#41]
Originally Posted By 50cal:
Cutting through the chrome lining cause any difficulties? It won't cause any issues, it's not like chrome plating on a bumper. |
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Posted: 1/16/2012 3:10:01 AM EDT
[#42]
Originally Posted By clange:
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? The 107ur doesn't require opening the gas port, it's already the correct size for function as an sbr. There is however a bushing or something of that nature in the gas port that makes it smaller for the 16" barrel, all you have to do is press off the front sight block and remove the bushing and your gtg. I don't know how much a gunsmith would charge to cut and crown one along with removal of the reducer in the gas port, but I would guess $100-$150 would be close. |
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Posted: 2/19/2012 12:56:48 AM EDT
[#43]
Originally Posted By Postal0311:
Is anyone doing crowning tool rentals? I dont see it on Dinzigs website anymore. |
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Posted: 2/19/2012 12:38:54 PM EDT
[#44]
the tool is relatively cheap enough to buy, I did, and is totally worth it. I have used it on 2 AKs and 1 FAL with fantastic results. You can multiple caliber inserts for it so you can use it on many weapons.
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Posted: 2/19/2012 2:13:08 PM EDT
[Last Edit: cowboy]
[#45]
Originally Posted By nictra:
the tool is relatively cheap enough to buy, I did, and is totally worth it. I have used it on 2 AKs and 1 FAL with fantastic results. You can multiple caliber inserts for it so you can use it on many weapons. Link to buy? ETA: Nevermind. found them on dinzang |
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OH, USA
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Posted: 3/10/2012 1:16:10 AM EDT
[#46]
I would never cut the crown flush. Leave at least a few millimeters to dress the crown in case it gets damaged or corroded. How did you guys remove the grommets?
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Posted: 3/13/2012 1:12:39 PM EDT
[#47]
Originally Posted By 50cal:
Cutting through the chrome lining cause any difficulties? i faced my muzzle with an 11° tool, and then recessed the crown a bit with a 90° tool. the chrome was a real PITA with the 90° tool, since it is basically cutting the hard chrome only. it took quite some time to recess the crown just a MM or so, whereas i was able to completely face the muzzle in just a few minutes. |
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MT, USA
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Posted: 3/19/2012 8:16:56 PM EDT
[#48]
Nice job, Looks simple enough as mentioned taking your time would be advised. They all look G2G! Thanks for Sharing.
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GA, USA
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Posted: 5/12/2012 7:22:00 AM EDT
[#49]
Originally Posted By micah360:
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 http://www.360wd.com/new-images/ak-104-clone.jpg 106U http://www.360wd.com/new-images/106u.jpg tools http://www.360wd.com/new-images/tools.jpg end products 107CR http://www.360wd.com/new-images/ak-104-muzzle.jpg 106U (I just recently re-crowned this one to get it flush) http://www.360wd.com/new-images/106-muzzle.jpg Did you have to cut your cleaning rod on the CR? Mine seems too long. |
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CO, USA
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Posted: 6/24/2012 5:24:00 PM EDT
[#50]
Originally Posted By BlenderWizard:
Did you have to cut your cleaning rod on the CR? Mine seems too long. yes... I cut the cleaning rod down to fit. |
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