Muzzle cutting

Pistolero

Well-Known Member
I bought a Brownell's muzzle crowning cutter, which does an 11 degree facing cut. I have found that
most rifles have pretty horribly uneven crowns. This thing guides on a pilot, and truly does cut true
to the bore.
Here is a shot of one of the best I have ever run into, a Marlin 336 in .30-30. It is just a hair off, when
the top is cutting a clean, sharp corner the bottom is probably .010 to .015 still uncut. Many have a
huge wide band visible uncut when you first reach a sharp corner at one side.

Here is a pic, have to look closely.

P1040681cropped.jpg
Sharp corner on right side of photo, but not reaching the bore yet on the left. This is a really good one, most are much worse.
I can't imagine the old "brass screw in a drill with valve lapping compound" would get you anywhere near a proper, square muzzle
cut, either.

Not magical, but they usually shoot a good bit more consistently after you recrown them. Some are dramatically better, like a
Win 94 that I have.

Bill
 
Last edited:

Pistolero

Well-Known Member
OK, finally got it done.

P1040688cropped _ done.jpg

Sharp edges all the way around, you can see each land has a sharp edge, and that this is micro groove rifling.

Bill
 

Pistolero

Well-Known Member
Here is the tool, fiver wanted to see it.

muzzle cutter small.jpg

I made the handle, just threaded 1/4 -20 instead of paying some high price for the Brownell's handle. Tool
is already expensive enough, but really worth having. You will be APPALLED to see how bad most muzzles
are cut, and they LOOK wonderful, but are NOT.

Bill
 

Brad

Benevolent Overlord and site owner
Staff member
I read an article by someone who then used a backed piece of emery to polish out the slight chattering left by the tool. I doubt that has any effect beyond cosmetics.

Looks very good Bill. I bet it shoots better too.
 

Pistolero

Well-Known Member
Funny you should ask. Just put a wipe of Brownell's T-4 on it with a .22 cleaning patch, let it sit
for about 20 seconds, wipe on a drop of oil.

muzzle done small.jpg

Looks about like the original blue.

Bill
 
Last edited:

Pistolero

Well-Known Member
Original crowns look like hell if you look closely, very rough tool marks, although usually
not chatter. IMO, when blued, it looks fine. Magnification shows a lot different than just
looking at it with the naked eye.
 

Pistolero

Well-Known Member
Nope, the bullets and hot gases do a nice job of that. I can't think of a way
to do it without risking messing it up.

Bill
 

Pistolero

Well-Known Member
OK, here is a nice sporterized 1903 Springfield that I fixed for my nephew. IME, this is
fairly typical of what you find.

crown_part_cut.jpg

muzzle almost.jpg
nearly there, (above)

muzzle done.jpg
Finished.

This gun shot much better afterwards.

Bill
 

Brad

Benevolent Overlord and site owner
Staff member
Ok Bill, how long for the Springfield? Roughly how man turns? How much pressure put on the cutter?

They look improved beyond all imagination. I am impressed.
 

S Mac

Sept. 10, 2021 Steve left us. You are missed.
Nice tool. Can you change the guide or are they caliber specific?
 

Will

Well-Known Member
Wow you wouldn’t think they would have that much trouble with a crown at the factory.

My encore muzzleloader wouldn’t shoot under 12” groups until I sent it to David White and had him recrown it.

 

Ian

Notorious member
And receiver faces, how do those get machined crooked? When you start digging into these things its amazing what you find. Neat tool, Bill, even if you own a lathe.
 

Intheshop

Banned
Probably should keep my typing finger holster'd.... oh well.

Uncle Jimbo gives what I consider an excellent comparison,valve seats. I have had several professionally built M/C race engines. These were "back in the day" so,not sure what the hot setup is now. But 3 angle valve seats had really come into their own back then.

The complexity of getting these individual bevels,accurately and with demonstrated repeatability, cut or ground..... ain't for the faint of heart. I'm not that good at explaining things but could show,pretty durn easily how these bevels are tricky to get perfect..... in a,how you hold your mouth right standpoint.

The big benny,as I see it on the hand tools for muzzles.... is the rate of cut vs machining. Which,as brought up above comes into question when the factory cranks them out. Speeds and feeds are all good till you get to complex bevels..... you gotta slow down. Something that factories don't do well.

Ian,there are some neat backdoor approaches to checking action centerlines..... that you won't see in print.