Recrowning a rifle muzzle.

Adam Helmer · #1 01-12-2009, 07:44 PM

I read a few gun magazine articles and had mixed success crowning old military arms. You win some and lose some, it seems. My latest failure was a 6.5mm Italian Carbine. I think the bore is so pitted and oversize that the muzzle crown is a moot point.

Does anyone have some suggestions on recrowning a rifle muzzle that I have not yet tried?

Adam

Larryjk · #2 01-12-2009, 10:40 PM

I always put them in the lathe (through the headstock) in a 4 jaw chuck and put a spud in the muzzle so I can center the bore using a dial indicator. Then take the cutoff tool and cut about 1/8 inch off the muzzle. Look at the rifling and see if each land is okay. If it isn't cut another 1/8 inch off and check again. Once you get even lands all the way around, you can bevel the muzzle and lap the entrance to the bore. When you finish, the muzzle should be even, each land should look like the others and to check for good lapping, pull a cotton q-tip through the muzzle. It shouldn't leave any cotton threads hanging from the muzzle.
Happy crowning.

Adam Helmer · #3 01-13-2009, 12:15 PM

Larry,

Many thanks. I would have to replace the barrel to get to good rifling at the muzzle. The bore of this carbine looks like the inside of my truck's tailpipe!

Adam

Mike Moss · #4 01-13-2009, 02:41 PM

Adam Helmer,

I have broken the corner on crowns and seen great improvement. I use a tapered grinding wheel in a drill.

I broke the corner on the 270 barrel on the left. It made a dramatic improvement.

The 7mm barrel on the right has always shot well.

Adam Helmer · #5 01-13-2009, 03:38 PM

Mike,

I have used tapered abrasive stones like in your picture and round-headed brass screws and crocus cloth with great results.

I am sure there is a Science, and an Art, to recrowning barrels. It makes my retirement interesting. I appreciate your helpful input; it seems I am doing something right when I am blessed with success.

Be well.

Adam

Larryjk · #6 01-13-2009, 05:45 PM

Mike Moss, If you have been using the stone to finish the crown, I think you have been lucky. Do what Adam suggests and use a round headed brass screw and lapping compound. Start with about 200 grit and finish with 400.
By the way, gunsmiths see things other folks don't when looking at guns. Look at your picture. I see jacket metal on the lands of the right hand barrel.

Mike Moss · #7 01-13-2009, 08:40 PM

Larryjk,

I have broken the corners on a number of rifles that were not shooting well and on every one there was a dramatic improvement. If it failed to work then perhaps there is some other cause for the inaccuracy or that the corner breaking did not do it.

If the corner breaking does not do it on some rifle then I will have my smith recut the crown.

Yes indeed there is metal fouling in that 7mm WSM's bore. Not only that but the rifle did not shoot that well on a test not long ago after the season. The rifle was shooting the 168 Berger VLD into 3/4 moa in October.

Thanks.

Larryjk · #8 01-14-2009, 12:20 PM

Mike Moss, I am always looking into barrels. I get a lot of rifles in with the complaint being a loss of accuracy. Usually, a thorough cleaning makes a marked improvement. I always look at the muzzle because that is the last place the copper fouling is removed. If the copper fouling is gone, I am already looking at the next potential problem, the crown. If the crown is good (not just okay), it is time to take the barreled action out of the stock and look at the bedding marks in the barrel channel and rub marks on the barrel. But that is another story.