Joe Carlos's approach to barrel break-in with the AR15 seems to really be focused on the gas port more than anything.
I think there is a lot to that, and his decades of experience with chasing accuracy in AR15s for the AMU are extremely difficult to argue with.
He has a very detailed procedure he uses for his uppers that involves shooting a round, applying copper solvent to the barrel, placing the upper in an inverted position so the solvent soaks into the top inside of the rifling, especially at the gas port, then cleaning after an 8hr soak, and inspecting with a bore scope. He will spend days doing that until the gas port is in a very clean condition with no burrs.
He got me thinking about break-in in a totally different light after listening to what he had to say, based on decades of daily experience with accurizing the AR15.
[video=youtube;PEuxyUxM-xA]https://www.youtube.com/watch?v=PEuxyUxM-xA[/video]
Joe Carlos
I don't use any brushes or other abrasives during break in. In part, you are trying to burnish shut the pores in the bore. Use of abrasives during break in will OPEN the pores which is opposite to your goal. AFTER break in, however, you will want to use an abrasive EVERY time you clean (each day you fire the rifle). The abrasive, such as a bore brush, will get the baked on hard carbon fouling that solvents won't remove.
Most barrel makers recommend NOT pulling a brush or patch back up thru the barrel as this can damage the crown.
Do NOT use bronze bore brushes with copper solvents as the solvent will "eat" the brush for lunch.
Do NOT mix solvents! For example, during normal bore cleaning I use regular Hoppes No. 9 on the brush and then follow with patches of Hoppes Bench Rest to remove the copper. You can also do that with regular Shooters Choice and their hotter copper remover. What you want to avoid is using Hoppes on the bore brush and then following with
a copper solvent made by a DIFFERENT company like Sweets or Shooters Choice.
Be very, very careful and always use a bore guide when using brushes. Brushes offer a lot of resistance to being pushed thru the bore because they are fatter than the bore. That resistance can cause a lot of cleaning rod flex bending the cleaning rod into the land and ruining the barrel.
For more information on gas gun barrel break in read my full article in the Oct. 2014 issue of "The American Gunsmith". For more information on bore cleaning read my article in the Jan. 2015 issue. These videos and my replies are very condensed versions limited by time and space.
I wrote a dedicated article in the May, 2015 issue of "The American Gunsmith" on this fire lapping topic and I recommend that you read that as I will only be able to hit a few highlights from it in this response.
When I went on as the match armorer for one of the major military shooting teams I found that I had inherited a lot of uppers that weren't shooting well. This was not due to barrels being shot out. Many of the uppers were not assembled properly so I tore them down and rebuilt them. The biggest culprit was failure to properly stabilize the barrel extension in the upper receiver. See my 2 pt. article in the March & April, 2013 issues of "The American Gunsmith" to learn how to do this right. Even a good barrel will fail to shoot optimally if the extension is not stabilized properly in the receiver.
I also found a lot of uppers that had gas tube to float tube contact resulting in gas tubes being improperly aligned with the bolt carrier key. To learn how to fix this see my March, 2014 article in "The American Gunsmith".
Having fixed all of the "usual suspects" I retested the uppers in the machine rest and found that some were still not shooting properly. The Team did not have enough budget money to purchase a bunch of new barrels to replace barrels that weren't worn out. So I resorted to fire lapping. In total as a military armorer and a civilian AR gunsmith I have probably fire lapped about 100 barrels. To the best of my memory every one of them improved! Remember, however, that these were barrels whose next step was going to be the trash can. I did not fire lap any barrels that were shooting well. Almost NEVER did such a barrel go from destined for the dumpster to being a tack driver. They did become "serviceable", however, and that was what I was hoping for.
So my advice to you and others is to fix all other potential problems before resorting to fire lapping. Fire lapping will shorten barrel life and that will be quite
variable. Barrels made from cheaper soft steel will suffer the most.
Almost every barrel maker will void any warranties if they find out that you have fire lapped their barrel. So if you have a barrel that is not shooting well I would contact the maker and see if they will replace it BEFORE resorting to fire lapping. I would also NEVER substitute fire lapping for a proper barrel break in. The video that I made is a condensed version of an article I wrote in the Oct., 2014 issue of "The American Gunsmith". I suggest you read it. It is important that you give ANY barrel about 200 rds. after the formal 10 shot break in before making judgments about it.
In conclusion, I am sorry this is so long. It is a very involved topic. I haven't had to resort to fire lapping a single barrel in about a decade. If you buy a barrel from a reputable custom maker who performs a proper hand lapping at the factory you shouldn't have to resort to work-arounds to get it shooting right. Barrels from companies such as Bartlein, Krieger, Brux, or Lilja should not require fire lapping.
If you have any further questions feel free to contact me directly at NCC1701@penn.com
Thanks!
I think there is a lot to that, and his decades of experience with chasing accuracy in AR15s for the AMU are extremely difficult to argue with.
He has a very detailed procedure he uses for his uppers that involves shooting a round, applying copper solvent to the barrel, placing the upper in an inverted position so the solvent soaks into the top inside of the rifling, especially at the gas port, then cleaning after an 8hr soak, and inspecting with a bore scope. He will spend days doing that until the gas port is in a very clean condition with no burrs.
He got me thinking about break-in in a totally different light after listening to what he had to say, based on decades of daily experience with accurizing the AR15.
[video=youtube;PEuxyUxM-xA]https://www.youtube.com/watch?v=PEuxyUxM-xA[/video]
Joe Carlos
I don't use any brushes or other abrasives during break in. In part, you are trying to burnish shut the pores in the bore. Use of abrasives during break in will OPEN the pores which is opposite to your goal. AFTER break in, however, you will want to use an abrasive EVERY time you clean (each day you fire the rifle). The abrasive, such as a bore brush, will get the baked on hard carbon fouling that solvents won't remove.
Most barrel makers recommend NOT pulling a brush or patch back up thru the barrel as this can damage the crown.
Do NOT use bronze bore brushes with copper solvents as the solvent will "eat" the brush for lunch.
Do NOT mix solvents! For example, during normal bore cleaning I use regular Hoppes No. 9 on the brush and then follow with patches of Hoppes Bench Rest to remove the copper. You can also do that with regular Shooters Choice and their hotter copper remover. What you want to avoid is using Hoppes on the bore brush and then following with
a copper solvent made by a DIFFERENT company like Sweets or Shooters Choice.
Be very, very careful and always use a bore guide when using brushes. Brushes offer a lot of resistance to being pushed thru the bore because they are fatter than the bore. That resistance can cause a lot of cleaning rod flex bending the cleaning rod into the land and ruining the barrel.
For more information on gas gun barrel break in read my full article in the Oct. 2014 issue of "The American Gunsmith". For more information on bore cleaning read my article in the Jan. 2015 issue. These videos and my replies are very condensed versions limited by time and space.
I wrote a dedicated article in the May, 2015 issue of "The American Gunsmith" on this fire lapping topic and I recommend that you read that as I will only be able to hit a few highlights from it in this response.
When I went on as the match armorer for one of the major military shooting teams I found that I had inherited a lot of uppers that weren't shooting well. This was not due to barrels being shot out. Many of the uppers were not assembled properly so I tore them down and rebuilt them. The biggest culprit was failure to properly stabilize the barrel extension in the upper receiver. See my 2 pt. article in the March & April, 2013 issues of "The American Gunsmith" to learn how to do this right. Even a good barrel will fail to shoot optimally if the extension is not stabilized properly in the receiver.
I also found a lot of uppers that had gas tube to float tube contact resulting in gas tubes being improperly aligned with the bolt carrier key. To learn how to fix this see my March, 2014 article in "The American Gunsmith".
Having fixed all of the "usual suspects" I retested the uppers in the machine rest and found that some were still not shooting properly. The Team did not have enough budget money to purchase a bunch of new barrels to replace barrels that weren't worn out. So I resorted to fire lapping. In total as a military armorer and a civilian AR gunsmith I have probably fire lapped about 100 barrels. To the best of my memory every one of them improved! Remember, however, that these were barrels whose next step was going to be the trash can. I did not fire lap any barrels that were shooting well. Almost NEVER did such a barrel go from destined for the dumpster to being a tack driver. They did become "serviceable", however, and that was what I was hoping for.
So my advice to you and others is to fix all other potential problems before resorting to fire lapping. Fire lapping will shorten barrel life and that will be quite
variable. Barrels made from cheaper soft steel will suffer the most.
Almost every barrel maker will void any warranties if they find out that you have fire lapped their barrel. So if you have a barrel that is not shooting well I would contact the maker and see if they will replace it BEFORE resorting to fire lapping. I would also NEVER substitute fire lapping for a proper barrel break in. The video that I made is a condensed version of an article I wrote in the Oct., 2014 issue of "The American Gunsmith". I suggest you read it. It is important that you give ANY barrel about 200 rds. after the formal 10 shot break in before making judgments about it.
In conclusion, I am sorry this is so long. It is a very involved topic. I haven't had to resort to fire lapping a single barrel in about a decade. If you buy a barrel from a reputable custom maker who performs a proper hand lapping at the factory you shouldn't have to resort to work-arounds to get it shooting right. Barrels from companies such as Bartlein, Krieger, Brux, or Lilja should not require fire lapping.
If you have any further questions feel free to contact me directly at NCC1701@penn.com
Thanks!
NRA Basic, Pistol, Rifle, Shotgun, RSO
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
www.AR15buildbox.com
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
www.AR15buildbox.com