My son got the barrel of his Browning Bar threaded and he installed a compensator. After putting the scope back on and firing at 200 yards, he was surprised that it was shooting 18" left. That seems extreme. Should the zero have changed that drastically?
How Much Does Barrel Threading and Compensator Install Change Zero?
- Thread starter beaglegun
- Start date
That's not what I wanted to hear
Did it group consistently?
Chopping the barrel and adding a brake is going to induce some change in the barrel harmonics and recoil management. I’d treat it as a brand new rifle.
If the grouping is all over the place that’s a different conversation.
Sheltowee
Well-known member
A couple of inches is not uncommon but 9 inches at 100 seems like a lot. Any chance the scope wasn't installed back straight? Did the smith remove the barreled action from the stock? If so, might it not have been put back in the same?
bluegrassdan
Active member
- Joined
- Mar 25, 2025
- Messages
- 77
I would expect a lot less change. I make sure that I cut the threads single point in the lathe and the bore is indicated to less than .0005" TIR so I know that the threads are concentric with the bore. I make sure that the customer brings the muzzle device so I can check thread run out on it, before I cut any threads on the barrel. Its not very common, but I have had to re cut the threads on the brake to make them concentric. This way I know everything is straight and the threads are cut to fit that brake and not loose in any axis. Harmonics will be affected, but they should only change the POI maybe a couple inches in extreme cases.
18 inches off zero tells me one of these may be the problem, assuming the scope was re mounted correctly and nothing is wrong with the base, rings or scope of course:
1. Crown got messed up and needs to be re cut square with the bore line
2. Brake is loose on the barrel- and no you don't need to Loctite it on, if you do then the threads were not cut to fit the brake correctly. It should torque down and stay put under recoil if the threads were cut right.
3. Threads are not straight and concentric with the bore. Shoot a target at 25 or 50 yards and see if the hole is round or not. Then look at the inside of the baffles, bet you see copper from a bullet strike. Also make sure that you have the correct size bore on the brake for the caliber you are shooting (generally about .030" over bore size is a good rule).
4. Most of the time the barrel has to come off the action to be threaded if the lathe headstock is too long for it to stick out of the chuck end far enough to thread. If the barrel is not re torqued on the action correctly, then your barrel is moving around more than it should. I torque all barrels to 90 foot pounds minimum, depending on the action it could be more.
Myself, if this were a customers rifle, it would not have left the shop that way. Check to make sure everything is tight (including the action screws) and re shoot it. If it does it again, stop and have a experienced, reputable gunsmith look at it.
18 inches off zero tells me one of these may be the problem, assuming the scope was re mounted correctly and nothing is wrong with the base, rings or scope of course:
1. Crown got messed up and needs to be re cut square with the bore line
2. Brake is loose on the barrel- and no you don't need to Loctite it on, if you do then the threads were not cut to fit the brake correctly. It should torque down and stay put under recoil if the threads were cut right.
3. Threads are not straight and concentric with the bore. Shoot a target at 25 or 50 yards and see if the hole is round or not. Then look at the inside of the baffles, bet you see copper from a bullet strike. Also make sure that you have the correct size bore on the brake for the caliber you are shooting (generally about .030" over bore size is a good rule).
4. Most of the time the barrel has to come off the action to be threaded if the lathe headstock is too long for it to stick out of the chuck end far enough to thread. If the barrel is not re torqued on the action correctly, then your barrel is moving around more than it should. I torque all barrels to 90 foot pounds minimum, depending on the action it could be more.
Myself, if this were a customers rifle, it would not have left the shop that way. Check to make sure everything is tight (including the action screws) and re shoot it. If it does it again, stop and have a experienced, reputable gunsmith look at it.
I ditched 3 BARs just 3 mos ago. 2 were new Mark3s in .300 WM & .270 Win and 1 was a Safari in .338 WM. On the Safari I was getting a 3-shot 2" group right off then a 5-6" group.with a POI change. Everything was always changing. Try pulling off the forearm. You will see the gas system is silver soldered in way down the barrel. AND, the swivel screws into that gas system. I got tired off trying to "fix it". I spent money on a barrel change, thinking that the barrel was worn out. Nope. In the end I decided it was a poorly designed rifle. My 3 BLRs shoot .75-1" groups consistently. It was frustrating and disappointing. I say, ditch that rifle.
Also, any scope I put on the rifle, the initial point the rifle would shoot was left 2' and down 18"!!
Also, any scope I put on the rifle, the initial point the rifle would shoot was left 2' and down 18"!!
