AR Sponsor
Posted: 5/9/2012 3:40:18 AM EST
|
I know WHAT a "government profile" barrel is. Thin under the handguards and larger diameter from the front site to the flash hider. I have seen an number of discussions claiming that they shoot just fine, they were a dumb idea and everything in between. Except, I have not found anything discussing "What were they thinking?" when this profile was specified.
The only advantage I can conceive is that the additional weight toward the muzzle would increase the polar moment and thus add a LITTLE to stability. Considering that the Les Baer CMP match rifle is bulked up to 17 pounds with tungsten weights (and a price to match) obviously weight is a good thing as far as steadying a rifle. But a few ounces on a select fire rifle? Again I have to wonder What were they thinking? Can anyone say? TIA, Ken Veteran NRA Endowment Member GOA Life Member Grass Roots NC Member |
| I think you are looking at it backwards. If I am not mistaken, the barrels were not made "thicker." They were made at the desired design thickness, and then turned down in spots to bring the weight down some. And they probably left the thicker parts thick for commonality of parts, such as the FSBs and the flash hiders. |
| They increased the thickness. The M16 and M16A1 profiles were thin lightweight barrels with .625 diameter at the gas block. The A2 "Government" profile barrel was made with a greater thickness from the gas block forward to resist bending in the field and to allow a longer period of sustained fire without overheating. The rest of the barrel was maintained at the original thickness to enable the M203 grenade launcher to be attached. |
|
Quoted:
They increased the thickness. The M16 and M16A1 profiles were thin lightweight barrels with .625 diameter at the gas block. The A2 "Government" profile barrel was made with a greater thickness from the gas block forward to resist bending in the field and to allow a longer period of sustained fire without overheating. The rest of the barrel was maintained at the original thickness to enable the M203 grenade launcher to be attached. +1 info. |
|
Quoted:
They increased the thickness. The M16 and M16A1 profiles were thin lightweight barrels with .625 diameter at the gas block. The A2 "Government" profile barrel was made with a greater thickness from the gas block forward to resist bending in the field and to allow a longer period of sustained fire without overheating. The rest of the barrel was maintained at the original thickness to enable the M203 grenade launcher to be attached. Sure, but the term government profile is not intended to denote the difference between a A1 barrel or an A2 barrel. Technically, the two barrels have nothing to do with each other. You either have an A1 barrel or you have an A2 barrel. The term is used to differentiate an A2 profile of barrel, from say a heavy barrel. Nobody has ever made an A1 barrel into an A2 barrel by making it thicker. That would be pretty stupid and would entail welding more steel onto it and re-machining it back it down to the proper diameter, or adding some kind of sleeve, not only externally, but also internally, so as to be able to change the rate of twist. |
|
Quoted:
Of course not, how in the world did you get that from my post? Do you think the OP or myself is actually suggesting that Colt makes a .625 1:12 twist barrel, adds material to make a .750 profile and changes the rifling to 1:7?
Quoted:
They increased the thickness. The M16 and M16A1 profiles were thin lightweight barrels with .625 diameter at the gas block. The A2 "Government" profile barrel was made with a greater thickness from the gas block forward to resist bending in the field and to allow a longer period of sustained fire without overheating. The rest of the barrel was maintained at the original thickness to enable the M203 grenade launcher to be attached. Sure, but the term government profile is not intended to denote the difference between a A1 barrel or an A2 barrel. Technically, the two barrels have nothing to do with each other. You either have an A1 barrel or you have an A2 barrel. The term is used to differentiate an A2 profile of barrel, from say a heavy barrel. Nobody has ever made an A1 barrel into an A2 barrel by making it thicker. That would be pretty stupid and would entail welding more steel onto it and re-machining it back it down to the proper diameter, or adding some kind of sleeve, not only externally, but also internally, so as to be able to change the rate of twist. |
Thanks for all the replies and interesting input. The diameter requirement to fit the M203 makes sense. M4 profile carbine length barrels have a groove cut in them about 1/3 of the way back from the muzzle. I have always heard that this was to accommodate attachment of an M203. Not sure that this has much application in the civilian market. Dealers in my area are always out of stock on M203s 
As far as the thicker section resisting bending... Yes of course IT would. However, I suspect the barrel would be more inclined to bend in the middle (which is also where it is thinner in this profile) rather than between the front sight and the muzzle. And regarding heat... I have to borrow back my Dillon's Machine Gun Magic tape and watch it again. I recall they got some barrels red hot during their night time shoot. I honestly don't remember if they turned red and the muzzle first and it worked back or a the chamber first and worked forward. Thanks again, Ken |
| Back in the day of the A1 there was suppose to be a rash of bent barrels from Joe trying to get into Cration crates and the new MRE boxes using the muzzle as well as bent barrels from various uses and abuses. The decision was made to increase the front thickness to correct this. May seem like it would bend more in the middle but it seems that they did not. |
I always love posting this tidbit 
Lt Col Dave Lutz (who goes by the handle "coldblue" here and on other boards) was intimately involved in the A2 upgrades in the 80s. He has stated they used straightness gauges on a number of M16A1 barrels during the preliminary tests, and found they got hung up near the gas port. So they first assumed barrels were being bent too easily in the field, and suggested (among other things) thickening up the barrel from the gas block forward. Lo and behold, they took a closer look and discovered that most M16A1's has a small, almost imperceptible burr from the drilling of the gas port, that interfered with the straightness gauge. So the A2 profile barrel really wasn't necessary, but hey, it works great on the KD range! |
|
Quoted:
I always love posting this tidbit
Lt Col Dave Lutz (who goes by the handle "coldblue" here and on other boards) was intimately involved in the A2 upgrades in the 80s. He has stated they used straightness gauges on a number of M16A1 barrels during the preliminary tests, and found they got hung up near the gas port. So they first assumed barrels were being bent too easily in the field, and suggested (among other things) thickening up the barrel from the gas block forward. Lo and behold, they took a closer look and discovered that most M16A1's has a small, almost imperceptible burr from the drilling of the gas port, that interfered with the straightness gauge. So the A2 profile barrel really wasn't necessary, but hey, it works great on the KD range! THIS, THIS, and THIS! A-2 profile was developed due to an erroneous conclusion that A-1 barrels were bent during bayonet training (with the bayonet lug acting as the fulcrum). Turned out that the barrels were not bent at all - the straightness gauge got hung up due to copper fouling that accumulated at the gas port due to the burr mentioned above. They then did ultra sonic cleaning on all of the failed barrels and discovered that they ALL passed afterwards. |
AR Sponsor
Win a FREE Membership!
Sign up for the ARFCOM weekly newsletter and be entered to win a free ARFCOM membership. One new winner* is announced every week!
You will receive an email every Friday morning featuring the latest chatter from the hottest topics, breaking news surrounding legislation, as well as exclusive deals only available to ARFCOM email subscribers.