Muzzle cutting

[Ian]

Valve seat cutters chatter too, hence the various angled stones and stone dressers. A brass lap still has its place........after the machine tool has corrected the geometry.

I'm no gunsmith but I've cut and crowned, and recrowned a few barrels on the lathe and cannot fathom how the factories can get them so so crooked. They must use some process other than feeding a form tool against the muzzle while the barrel is indicatedi in a lathe....or even half-assed chucked up in a worn-out three-jaw.

 

[Pistolero]

I have also done engine work for money, put myself thru grad school overhauling engines and doing
clutches and brakes on VWs, mostly. I still have my Neway valve seat cutting tools, damned expensive
at the time for a very poor college student ($100 got you a top grade valve job parts and labor in those
days). But the Neway cutters are real precision tools, do a proper three angle cut seat concentric to
the guide, because they pilot off of the guide. Neway is carbide cutters held by tapered locks in dovetails
in the face of a precision aluminum cutter head, with a steel center to run on the pilot. Fine tools for sure.
Cut a 45 degree seat, then a 75 and 15 degree cutter to narrow it and locate it properly on the valve
seating face. just a touch of fine lapping compound and done.

As to doing the Springfield, probably at least 50 or 60 or more half turns, moderate pressure, like 10 to 15 lbs.
I want to keep it cutting, not let it slide and the barrel steels don't exactly cut like butter. Sliding will dull the
cutter very quickly, you want to have enough pressure to cut, but not go nuts.

The Marlin today was done standing, easy to push down on the barrel, butt on floor. Three sessions
of cutting, pix between (after examining under magnification and photos). First one was only about 10
half turns to see how the crown was, that one was fairly good. Then about 15 or 20 half turns, and it was
getting close. Then about 10 more half turns. That one was pretty easy, minimal cutting.
I did a Win 94 and it was about as bad as the Springfield. Seems like many/most guns have really pretty
bad crowns from the factory.

As to "even if you do own a lathe", it's not easy to set up a lever gun in a lathe to crown the bbl, same for many
other guns. Sure, when you have the bbl out, easy peasy. Installed, the hand cutter is the way. I suppose I
could strip it all the way down to bare receiver, no wood, no mag tube and put it thru the headstock hole,
but that is a lot of disassembly and reassembly. This was maybe 10 to 15 minutes work, less the photo
time.

Thanks for the compliment. I was going to do this rifle, wondered how many had a tool like this and used
it. I think many here would benefit from it.

Bill

 

[Pistolero]

I agree, Ian. No easy way to see how they get them so messed up at the factory. Seems like
even moderately normal methods would get better than they get.

Bill

 

[Pistolero]

Well, mine says 11 deg cutter, but now they call it 79 deg cutter.

https://www.brownells.com/gunsmith-...utters/79-muzzle-crowning-cutter-prod628.aspx

I bought a .30 and 7mm pilots, made the simple 3/8 aluminum sq bar handle, will make any others that I need now with the lathe handy.

Bill

 

[Ian]

11 vs. 79 has caused endless entertainment and spirited arguments among shooters on precision rifle boards for years. Tomato tamato.

Try threading a levergun muzzle for a 10" suppressor with the barrel on the action and making it true enough to prevent baffle strikes. How the heck do you indicate that, especially when the chamber is so crooked to the bore centerline that there is no hope of indicating off of it with a long wire? Hang a grid target on the wall to the left, pull off the tailstock, and MK-1 eyeball it from the muzzle end. Pita to keep having to set up the muzzle rod for the test indicator after making spider adjustments, but it works. Believe me, I tried to figure out a way to make an outside-turning fixture whuch could be cranked by hand to do all that, but the thread feeding mechanism was too complex for me to build. Tools to do simple crowning jobs without having to strip the rifle or even remove the front sight are definitely called for.

 

[Pistolero]

Yep. The Brownell's tool is not cheap, but works well and pilots nicely on the bore.

A friend thread barrels for suppressors for money...I think he pushes them thru the headstock and
centers up the chamber end exterior, then drives an aluminum or brass pin in the muzzle, just groove diam,
so the rifling engraves a bit and holds it true. Center drilled prior to tapping into muzzle. I think this is correct,
I looked at his setup some time back, once.

Bill

 

[Pistolero]

S Mac - the pilots are interchangable, but each is a close fit on the bore diam.
Setscrew on a flat on the pilot's pilot into the cutter body.

Bill

 

[Pistolero]

I threaded an AR bbl for flash hider. Grabbed the chamber end in the chuck,
left the front sight on (watch out!!!) and put an aluminum pin into the barrel, slight
interference fit, with a center drill in it when I made it. Worked fine.

 

[Eutectic]

Valve seat cutters chatter too, hence the various angled stones and stone dressers. A brass lap still has its place........after the machine tool has corrected the geometry.

I have to agree with Ian here........

I almost work on every barrel crown I own! I have machined crowns; I've reamed them with a piloted tool as well..... I still lap to finish

Why??? I think you get a more uniform release. And the best of machine/reamed edges may have a slight burr unseen. I lap until I see an even contact under magnification. Yes, you will see a slightly heavier contact on land edges..... Experience has taught me that it does no harm and more times than not helps! Our bullet sees that same uniform release.......

My buddy made a custom .358 Win on a stainless Remington Model 7. His smith used a 5 land and groove Pac-Nor barrel 1 in 12". I liked the barrel on my first look through! It had a nicely machined crown that looked perfect even under magnification. The new barrel was copper fouling easy as Todd broke it in. The thing was really shooting too other than an intermittent flier up to an inch and a half out at 100 yards. We (I) blamed the fouling. We were on my shooting bench and I looked into the muzzle in the bright sun.... I went in the house and got more magnification. One land and adjacent groove had bright fouling right on the very sharp edge only! I showed Todd....... "What can we do?" Todd asked. "I'd lap it" I replied. "My gunsmith is 250 miles away!!!"......... "We don't need him" I grinned.
I lapped that barrel right on my shooting bench in 10 minutes. I gave Todd my magnification and showed him the even 'touch' all the way around.
The fliers went away! He's shooting Nosler 225gr partitions into 3/4" at 100 and has killed a nice elk with the gun.

Pete

 

[Ian]

The other nice thing about a lap is it can be turned both directions.

 

[Eutectic]

I might add a crown machined or reamed first takes very minimal lapping to finish.

 

[Kevin Stenberg]

It looks like i just found my next tool purchase.

 

[Rick]

It looks like i just found my next tool purchase.

That is tempting isn't it? Surprised I haven't already had my head stuck in the safe looking at muzzles. Probably cause I'm afraid of what I might find.

 

[Pistolero]

I shot three groups at 100 with the Marlin today. Two with 150 gr, two brands of bullets, and
one was 170 gr. Different powder on the 170. All were under 2", two were about 1.5". With
a 3X scope, aiming at a 6" bullseye at 100, this is as good as I am likely to get. Very pleased, and
note that this one had a really nearly correct crown, it was only a tiny bit out. Prior to recutting the
crown this rifle would shoot a few loads well, but most loads went into 3" to 4" at 100 yds.

Now, I have a 94 Win that is going to likely get a new barrel. When I cut it, it became pretty clear
that the hole is NOT in the center of the muzzle......that is not fixable. I will actually do some
measurement before I buy another barrel, but it sure looks like it is way off center in my photos.
Possibly the original muzzle was just so far off angle.....but I bet it is not in the middle.



And it still shoots just as poorly, 4-5" at 100 with most loads. Pretty sure when I measure it, it will have the bore
about .100 or so out of the center of the exterior. That is never going to shoot well.

Bill

 

[Ian]

Wow, that's terrible. Oh well, good excuse to put a premium barrel on it and lap the threads.

 

[Pistolero]

Not likely, Ian. I will just purchase a Win 94 bbl online and screw it in. Just
playing the odds. It is a Win 94, will never, ever be any sort of a tack driver,
but it deserves a decent barrel. I would expect 2" groups at 100 from a good
barrel, properly installed, but nothing heroically done.

I'll put a gauge pin in the muzzle, use a depth gauge to see how far the bore is
from the exterior surface of the barrel at four locations.

Bill

 

[Ian]

It is a Win 94, will never, ever be any sort of a tack driver,

I disagree with that, seen some post '64 examples that shot amazingly well with good cast bullet loads, but I sure do get not wanting to profile and finish a premium blank for a levergun. Got the tee-shirt for that and would have to have a very compelling reason to do it again.

 

[Eutectic]

I have a Winchester Model 64 in .25-35. That thing may just think it's a heavy barreled bolt gun at times! Ol' Townsend Whelen wrote the .25-35 WCF was the most accurate lever gun cartridge and I won't argue with the ol' boy!

Pete

 

[Pistolero]

Measured the barrel wall thickness. Turns out they just cut that muzzle crown really wonky, it isn't nearly
as far out as the crown would make you (and me!) think from the photo above - meaning the Win 94.

I get about .006 to .008 off center for the bore in the barrel at the muzzle. I have nothing to
compare that to, but IMO, it should have been turned between centers set into the bore, but clearly
was NOT. New (used, looks minty) barrel on the way.

Starting to wonder what would happen if I pulled the barrel, turned the outside down between
centers to clean up and then reinstalled it, put a new ramp and front sight on. Would cost near
to nothing, a bit of time, and would be interesting to see if that barre would shoot any better or
if it is just throwing good time in the trash on a junk bbl? Anybody ever try this?

Bill

 

[Ian]

My 336 Texan was worse than that (about .015" off-center at muzzle) and has turned in a heap of sub-moa groups at 100 yards, more like 5/8" most of the time if I'm on my "A" game on the bags. I threaded it and still haven't re-crowned it, don't want to mess up a good thing.

Where most barrel profiles deviate from bore is in the middle, affecting POI as the barrel heats. Belt sanding the profile on a lathe does all kinds of weird things.