I'm refering to the barrel on this page: http://www.rockriverarms.com/item-detail.cfm?ID=AR0205ASY&storeid=1&image=bblr4.gif (except mine is light under the handguards). What I would like to to do is remove the mock sepressor and have the barrel cut down and threaded so with an A2 flash hider installed, it would be 16" OAL. If anyone has ever done this where did you get it done and do you have any pictures? Thanks.

I have the same barrel and am going to do the same. ADCO does this for a good price.

Haven't done it yet, but I'm planning on sending my barrel to Adco next week (same setup) except I will be getting a Phantom attached instead of an A2.

I also have the same barrel.  However, there have been some comments made that indicate there may not be enough metal on the end of the barrel, after the mock suppressor is removed, to actually allow for threads to be cut.  I am guessing they are cutting the threads from the area currently covered by the mock suppressor.  Is that correct?

Have the good folks at ADCO already done this and proved it's viability?

The barrel is already 16 inces overall length, how can there not be enough steel there? The old break is just a press on. The barrel would actualy have to be cut down to make the OAL 16 inches with the A2 FH perminately attached.

Hot link to the aforementioned page

Quoted: The barrel is already 16 inces overall length, how can there not be enough steel there? The old break is just a press on. The barrel would actualy have to be cut down to make the OAL 16 inches with the A2 FH perminately attached.

Length is not the issue, barrel diameter in the area where the mock suppressor exists is the concern.  I was told by Robert from RB Precision that the barrel diameter is turned down somewhat for the the MS to be pressed on.   The amount of metal removed from that area may not allow for adequate diameter to exist to then cut threads in that area.  That is the concern.  I'm not saying it is a fact, just that it has been brought up as a concern.  I just want to know if ADCO has done this already and assured themselves that there is indeed enough metal to be cutting the threads for a real flash suppressor.

I did mine the hard way, before it was "popular". I bought a Bushmaster Shorty HBAR upper from another user here and had him ship it to a machinist/gunsmith in FL (March 2000) that is popular with ar-15 members. I am not going to name him here on an open forum, as it was a very distressing situation and I don't want to say anything publicly that could be interpreted as slander. If you want the name, email me.

He cut the M4 profile, shortened the barrel and pinned a Wilson Combat muzzle brake on. He had to do it twice (he had to buy me a new barrel) because he screwed it up the first time, including an attempted "repair", but eventually got it right.

I then had a Bushmaster M4gery but with an A2 upper, finally this week had the upper swapped for a flat-top. Here is what it looks like now.



Here is the detail of the barrel, it is contoured under the handguards too



I'm not sure that I would recommend this person, yes I was happy with the finished product, but he was slow and I had to send the upper back (at my cost) due to his mistake, which could have resulted in a catastrophic accident.

When he returned the upper the second time I was pretty sure my near new upper and bolt were replaced with someone elses used parts. It wasn't worth arguing about, I just wanted to put it behind me.

The gas tube was slightly misaligned, and was catching on the bolt carrier key. I took it into a local gunsmiths, he was shocked to find the barrel was loose (hadn't been torqued properly) and needed another complete rotation to be right! He asked me if I had been shooting it, I admitted I had and he told me I was lucky nothing bad had happened.

No matter who you get to do the work, get recommendations!

madkiwi

Check this thread for a picture of the barrel underneath the faux supressor:

ar15.com/forums/topic.html?b=2&f=130&t=143516

This was back when I was considering just pressing the faux supressor off and threading the end. However, now that I have a 16" M4 barrel coming, I thought I'd go for variety and just have my old RRA M4 barrel cut to 14.5" and have a phantom attached.

Here's my take on this whole Rock River barrel threading thing.  Using the following pictures as a reference:





The Rock River faux flash hider is actually a bored out A2 FH, which measures 1 3/4" in length.  The above pictured barrel has a reduced diameter with the same length and the bored out FH is pressed on.

Now look at the threaded portion of the preban barrel pictured in the lower pic.  The threaded portion of that barrel measures 5/8".

So, if you were to thread the Rock River postban barrel with the faux FH pressed off, you would have the remaining 1 1/8" of the undercut profile of the barrel with the raised area where the faux FH showing after you threaded the barrel.  That would likely be the most retarded looking barrel I could imagine.

Take away the faux FH and the length of barrel underneath it and what you really what have left is a 14.5" M4 profile barrel.

So, for a proper looking barrel configuration, you really need to press of the fake FH, trim the barrel to 14.5" and permanently install a Vortex or Phantom.

Option #2 is iffy, but I think you can get away with it legally.  You trim all but 5/8" of the under cut barrel off (where the faux FH used to be) and you thread it and permanently install an A2 FH.

Either way, for a normal looking barrel configuration, barrel material has to be removed and will end up with a barrel less than 16" and it MUST have a permanently attached muzzle device to satisfy NFA requirements.

Will someone PLEASE walk through this.  I am 99% sure this is the way it must be done.  I had one of the Rock River barrels and the faux FH came off while I was shooting it, so I got a really good look at was underneath the faux FH.  I really don't see any other way to do this and have it look "normal".

Quoted: The barrel is already 16 inces overall length, how can there not be enough steel there? The old break is just a press on. The barrel would actualy have to be cut down to make the OAL 16 inches with the A2 FH perminately attached.

thats exactly why i got a pre-ban version so I would have the full 16" barrel...  

Thats why I did not get one. I want 16 inches overal length. And the fake supressor on the RRA is NOT a bored out A2 flash hider. The press fit fake supressor is WAY out of demension of the real one, just try to slip a BFA on it, it wont work. I would venture to say that there will be enough room, but if not then I will try some other way...

Quoted: Thats why I did not get one. I want 16 inches overal length. And the fake supressor on the RRA is NOT a bored out A2 flash hider. The press fit fake supressor is WAY out of demension of the real one, just try to slip a BFA on it, it wont work. I would venture to say that there will be enough room, but if not then I will try some other way...

the preban version is 16" OAL w/o muzzle device

Again, I see that...

Quoted: Thats why I did not get one. I want 16 inches overal length. And the fake supressor on the RRA is NOT a bored out A2 flash hider. The press fit fake supressor is WAY out of demension of the real one, just try to slip a BFA on it, it wont work. I would venture to say that there will be enough room, but if not then I will try some other way...

I will verify that.  I tried to put a shoot-through muzzle cap on the mock suppressor and it is way too tight.  The MS is definitely larger in diameter than an actual flash suppressor.

Does ADCO or anyone else have any pics of the barrels they have done this to?  I'd like to see what it actually looks like once accomplished.

I have not seen any but have just been told that they were the way to go. I will call them some time after they reopen next week...

I can't deny what you are saying, since I no longer have one to compare to.  At a minimum, the length of the faux vs. A2 has to be pretty close, IIRC.  It is definitely longer than the 5/8" of threading found on standard threaded muzzle barrels, by a long shot.  I believe you are still battling a SBR issue when you try to thread these barrels and install any type of FH.  I just don't see any way around it, unless you like a funky step down after your FH for about an inch, then a step back up to standard barrel profile.

As a rough guesstimate, look at the pick of the Rock River barrel with the faux removed.  Just for ease of numbers, let's say the undercut profile diameter is 0.500".  Now compare that to the length of the undercut area.  My eyes say 2-3 times the diameter.  So you are looking at 1 - 1  1/2" of undercut profile and you can only realistically fit 5/8" of that into a FH.  You will have left over material, say 1/2 - 1" of it to deal with.

If the flash hider is permanently attached and the overall length WITH the permanently attached muzzle devise is 16 inches or over then it is NOT a SBR... Also the length of the fake and real FS are not in question, the diameters are what I was doubting.

Quoted: If the flash hider is permanently attached and the overall length WITH the permanently attached muzzle devise is 16 inches or over then it is NOT a SBR...

Exactly, that is why I stated above that ANY muzzle device attached to one of these barrels that has been threaded will have to be permanently attached.

You need 0.498" to properly thread a barrel, you could probably get away with a little less.  I'm guessing, just by the pic above that these are very close to that number.

Let me try to clarify a bit more

1. Press off fake supressor
2. cut barrel down and thread to a length that would allow an OAL of 16 inches with the muzzle devise attached.
3. Permanently attach an A2 supressor to the barrel for an OAL of 16 inches...

Quoted: Exactly, that is why I stated above that ANY muzzle device attached to one of these barrels that has been threaded will have to be permanently attached.

Well no shit, thats what we were talking about doing from the beginning...

Here's a first, I'm quoting myself:

Originally Posted By mongo001 Option #2 is iffy, but I think you can get away with it legally. You trim all but 5/8" of the under cut barrel off (where the faux FH used to be) and you thread it and permanently install an A2 FH.

We are saying the same thing, but I'm not so sure that all others participating see the issues at hand here.

yeah

OK, let me say something real quick

Now if you do this you dont get a 14.5 inch barrel if you permanently attach a FS, you get 16 inches OAL. I know you are saying the same thing but I am just trying to clarify for everyone else

Quoted: OK, let me say something real quick Now if you do this you dont get a 14.5 inch barrel if you permanently attach a FS, you get 16 inches OAL. I know you are saying the same thing but I am just trying to clarify for everyone else

That is correct.  You SHOULD be able to do exactly that and PERMANENTLY attach an A2 FH and your overall barrel length SHOULD be at or over the 16" limit.

The point is, the second you cut any length off of that 16" barrel, your muzzle device will HAVE TO BE PERMANENTLY ATTACHED.

Good photo shop work.  Wish I could do that.

thank you... thats what we were talking about doing since the start of the thread...

Ok, but when you see statements like "The barrel is already 16 inches overall length" or "Length is not the issue", it makes you wonder if all have a full grasp of the mechanics behind the process.  I've got my ass covered, just making sure others keep theirs covered as well.

yeah, the "length is not the issue" was about whoever it was saying that the press on FH was a real one bore out. I said it was not the same size and someone said they were in fact close in length when I ment that the diameter is not the same. And the "barrel being 16 inches" was because someone said that they got a preban that was 16 inches OAL because the post ban wouldnt work for what we were talking about (too short supposedly) when all this person had to do was to read the entire post before posting and they would see that thats what we were talking about clear as mud right?

Ya.

Quoted: The point is, the second you cut any length off of that 16" barrel, your muzzle device will HAVE TO BE PERMANENTLY ATTACHED.

Ooohhhhh....now it makes perfect sense. I wasn't aware of this rule. Does this mean that all people that have 14.5" barrels and the flash hider to make it 16" OAL have them pinned on (unless they are SBR registered).

Quoted: Quoted: The point is, the second you cut any length off of that 16" barrel, your muzzle device will HAVE TO BE PERMANENTLY ATTACHED. Ooohhhhh....now it makes perfect sense. I wasn't aware of this rule. Does this mean that all people that have 14.5" barrels and the flash hider to make it 16" OAL have them pinned on (unless they are SBR registered).

Pinned and welded  over the pin hole is probably the most common and cleanest method.

Silver solder with a melt temp over 1100F is another ATF approved and widely used method.

There are others, but they all involve welding, either tack welds or circumferential welds, neither of which I have seen used.

You guys forget.........if your barrel is chrome lined, then you have a problem....as cutting a chrome lined barrel can destroy it.  

Quoted: You guys forget.........if your barrel is chrome lined, then you have a problem....as cutting a chrome lined barrel can destroy it.

Not true.  ADCO has cut several with NO problems.