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Posted: 9/19/2004 6:30:30 AM EST
I'm thinking of upgrading my fake flash suppressor M4gery barrel to either 16" with fs or should I go to 14.5" and make sure the fs adds another 1.5" for a total of 16"?

Does the fs have to be permanently attached with a 14.5"?

What constitutes "permanently attached"? If I get a pronged fs and damage a prong, I don't want to have to scrap the whole barrel.
Link Posted: 9/19/2004 6:32:09 AM EST
[Last Edit: 9/19/2004 6:33:45 AM EST by BB]
My bushmaster M4-gery had a 14.5" M4 barrel and a pinned and welded phantom that took it to 16.1".
If I was going to do it again, I'd pin and weld a gemtech lugged flash hider on there so I would have the ability to add accessories if I wanted later.
Link Posted: 9/19/2004 6:37:22 AM EST
If your 14.5" barrel does not have a FH permenantly attached it is considered an SBR, and must be registered accordingly, and you must go through the approval process to be able to own the weapon.

So, yes you 14.5" barrel must have something permenantly attached to it to increase the total length to 16".
Link Posted: 9/19/2004 6:38:03 AM EST
I'm planning on going with the 16" barrel with threads. That way I have the option to remove FSs easily.
Link Posted: 9/19/2004 7:08:48 AM EST
Personally for me, I like the 16" BBL, it is just right. Actually your BBL will be 16" plus another approximately 1.5" for the GI flash suppressor, it would add to that the overall lenght. I think the Phantom and Vortex flash hiders are even a tad little longer.
Link Posted: 9/19/2004 7:27:38 AM EST
Here's one take on it.

www-2.cs.cmu.edu/afs/cs.cmu.edu/user/wbardwel/public/nfalist/atf_letter40.txt

" DEPARTMENT OF THE TREASURY
Bureau of Alcohol, Tobacco and Firearms
Washington, D.C. 20226

JUN 18 1998 F:FPD:FTB:RAT
3311


Dear Mr. :

This refers to your letter of March 31, 1998, in which you ask
about permanently attaching a muzzle device to various firearms.

A muzzle device, such as a muzzle brake or barrel extension, which
is attached to a barrel by means of welding or high temperature
silver solder having a melting point of at least 1,100 degrees
Fahrenheit, is considered to be part of the barrel for purposes of
measurement. A seam weld extending at least one-half the
circumference of the barrel or four equidistant tack welds around
the circumference of the barrel are adequate for this purpose.

A firearm having a muzzle brake, cap, or barrel extension
permanently attached by those same methods to cover the threads on
a barrel, would not be considered to have a threaded muzzle.
Please note, however, that any muzzle device or barrel extension
which functions as a flash suppressor or grenade launcher would
still constitute one of the qualifying features of a semiautomatic
assault weapon as that term is defined in 18 U.S.C. section
921(a)(30(B). Industrial adhesive products are not an acceptable
method for permanently attaching a muzzle device."

(obviously any references to the AWB no longer apply)

The Phantom and Vortex FS's are 2 1/4" long.
Link Posted: 9/19/2004 7:32:42 AM EST
I agree with the 16" and an A2 flash suppressor. I just like the A2 FS better.

I do have a 14.5 with Phantom though. Here's the thing about permanent installations. Nothing is permanent! The ATF say it must be silver soldered or blind pinned blah, blah but if a gunsmith can remove it in 2 minutes with a torch or I with a Dremmel why waste the time and money. If it's not readily removeable and or requires tools to do so WTF.

I'd say JB weld it yourself to comply with the law and not some made up ruling and move on, but nobody will agree with me in public I'm sure.
Link Posted: 9/19/2004 7:38:53 AM EST
[Last Edit: 9/19/2004 7:39:41 AM EST by norman74]
If I had it to do over again I'd get the 14.5 with the Gemtech Bilock flash suppressor permanently installed. However, you should make use of the following information when choosing a barrel length
www.ammo-oracle.com/body.htm#fragrange
By switching to the 14.5" barrel over the 16" you essentially lose 50 meters of effective range.

Link Posted: 9/19/2004 8:53:42 AM EST

Originally Posted By norman74:
If I had it to do over again I'd get the 14.5 with the Gemtech Bilock flash suppressor permanently installed. However, you should make use of the following information when choosing a barrel length
www.ammo-oracle.com/body.htm#fragrange
By switching to the 14.5" barrel over the 16" you essentially lose 50 meters of effective range.




That has never washed with me. 1.5 in cannot make that much of a difference. Cutting 1.5in off of a AR barrel doesnt make that much a difference at any other point.
The difference is more like 15m, and hence hardly noticable.

Can you notice a difference between the 20in Normal and 18.5" SPR barrel? Or between the 11.5 and 10in? To have that big a jump is just off the curve.

Link Posted: 9/19/2004 9:03:25 AM EST
[Last Edit: 9/19/2004 9:06:58 AM EST by norman74]

Originally Posted By ArmdLbrl:

Originally Posted By norman74:
If I had it to do over again I'd get the 14.5 with the Gemtech Bilock flash suppressor permanently installed. However, you should make use of the following information when choosing a barrel length
www.ammo-oracle.com/body.htm#fragrange
By switching to the 14.5" barrel over the 16" you essentially lose 50 meters of effective range.




That has never washed with me. 1.5 in cannot make that much of a difference. Cutting 1.5in off of a AR barrel doesnt make that much a difference at any other point.
The difference is more like 15m, and hence hardly noticable.

Can you notice a difference between the 20in Normal and 18.5" SPR barrel? Or between the 11.5 and 10in? To have that big a jump is just off the curve.




OK, have it your way then. I'm no expert, so I'll defer to everyone else that knows more than me. Take it or leave it, it's no sweat off my balls either way. I just always assumed that in barrels less than 16" there was unburned powder left after the bullet left the barrel which accounted for the dramatic loss in velocity.

FYI, they don't use M193 or M855 in the SPR
Link Posted: 9/19/2004 9:12:57 AM EST
[Last Edit: 9/19/2004 9:14:12 AM EST by ArmdLbrl]

Originally Posted By norman74:

Originally Posted By ArmdLbrl:

Originally Posted By norman74:
If I had it to do over again I'd get the 14.5 with the Gemtech Bilock flash suppressor permanently installed. However, you should make use of the following information when choosing a barrel length
www.ammo-oracle.com/body.htm#fragrange
By switching to the 14.5" barrel over the 16" you essentially lose 50 meters of effective range.




That has never washed with me. 1.5 in cannot make that much of a difference. Cutting 1.5in off of a AR barrel doesnt make that much a difference at any other point.
The difference is more like 15m, and hence hardly noticable.

Can you notice a difference between the 20in Normal and 18.5" SPR barrel? Or between the 11.5 and 10in? To have that big a jump is just off the curve.




OK, have it your way then. I'm no expert, so I'll defer to everyone else that knows more than me. Take it or leave it, it's no sweat off my balls either way. I just always assumed that in barrels less than 16" there was unburned powder left after the bullet left the barrel which accounted for the dramatic loss in velocity.

FYI, they don't use M193 or M855 in the SPR



They do use M855 in the SPR all the time, it is the backup ammo, there isn't exactly a unending supply of Mk262.

And there is unburnt powder left in the shorter barrels, but powder should burn in a regular fashon, not have this huge jump in one section of the barrel. If there were, then that would actually be something that could be addressed by changing powder and you could therefore tune it away.

I wish Tat and Brou would go back and shoot that section again and compare a 16 and a 14.5 head to head.
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