733 barrel - Page 1

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Posted: 10/22/2021 1:47:05 PM EDT

Trying to find a barrel for my 733 build. Is the correct barrel .625 under the gas block? Did they ever use .750 barrels under the gas block?

Having trouble finding a lightweight .625 barrel.

Posted: 10/22/2021 4:20:38 PM EDT

[#1]

Quoted:
Trying to find a barrel for my 733 build. Is the correct barrel .625 under the gas block? Did they ever use .750 barrels under the gas block?

Having trouble finding a lightweight .625 barrel.

View Quote

I believe you'll find the 733 in either .625 or .750 gas block configuration. I jumped into the retro building scene way late (even though I'm retro) and mainly used .625 gas block Colt SP1 Police trade in & Model 6520 barrels then cut them to length before they were available for a short time by aftermarket companies. In the brochure I'm attaching (1988) you'll see the barrels were pencil .625 size. As time went on you'd find in either size. Good luck on finding a .625 OR .750 16" or less barrel. They are out there.....

Posted: 10/22/2021 5:02:16 PM EDT

[#2]

I think the 733 only used a .625 barrels.
The .750 ones were used on more recent 933

Posted: 10/22/2021 5:28:39 PM EDT

[#3]

The later 733s did have 11.5" A2 profile (.750) 1/7 barrels attached to A2 upper receivers. I built this version a few years ago since I had an A2 upper laying around.

Attached File

733s that used 603 and C7 type uppers had the 11.5" A1 profile (.625) 1/7 barrels.

Posted: 10/22/2021 9:22:48 PM EDT

[#4]

Until Colt’s recent change to the 933/6933 barrel, I’ve never seen a factory 11.5” Colt with a 0.750” gas journal. To those claiming Colt did so, please post references. I’m very curious about this.

Posted: 10/23/2021 2:33:47 PM EDT

[#5]

There are 3 pictures that I know.
One is in a book similar to “Black rifle” there is a 733 with a2 upper, lower with 720 barrel.
Second is a Picture I think navy seal vbss with a2 upper and 11,5, 720 barrel.
Third this SWAT guy.
When I find the rest then I will post them.

Posted: 10/23/2021 9:47:47 PM EDT

[#6]

Quote History

Quoted:
There are 3 pictures that I know.
One is in a book similar to “Black rifle” there is a 733 with a2 upper, lower with 720 barrel.
Second is a Picture I think navy seal vbss with a2 upper and 11,5, 720 barrel.
Third this SWAT guy.
When I find the rest then I will post them.

https://drive.google.com/uc?export=view&id=1-2V_EylR3SrW0ddOAftHSS9ovtqwxpkg

View Quote

Well hot damn. That is really interesting. I don’t know how I’ve not seen this previously.

Posted: 10/24/2021 6:07:39 AM EDT

[#7]

Well found this.. the link doesn’t work here in EU but was able to see just the pic.. A2 733 with 750 barrel.. not sure if it’s factory

https://www.apexgunparts.com/colt-m720-ar15-cm-upper-receiver-assy-11-5-heavy-barrel-vg.html

Posted: 10/25/2021 8:47:58 PM EDT

[#8]

Doublestar,DD,and 1 other I cant remember from when I was doing mine. I went with a Colt FBI though.Check the colors on those barrels if you are wanting a match. Spikes,I remember now. All BO I think but those are hard as hell to find. Specialized armament probably has one. For about 800 bucks.

Posted: 10/25/2021 10:23:07 PM EDT

[#9]

Quote History

Quoted:
Well found this.. the link doesn’t work here in EU but was able to see just the pic.. A2 733 with 750 barrel.. not sure if it’s factory

https://www.apexgunparts.com/colt-m720-ar15-cm-upper-receiver-assy-11-5-heavy-barrel-vg.html

View Quote

The barrels are marked B MP. Bushmaster.

[ARCHIVED THREAD] - 733 barrel

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