DIY barrel crowning

manbearpig

manbearpig

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I have an old Mosin that was converted into a trunk gun. This is a completely non-collectible Mosin: its post-war, import marked, arsenal refurb, etc.

I've done as much as I can to accurize it: glass bedded into an ATI synthetic stock, trigger shim job, aftermarket Mojo micro-click sights, etc. The bore is shiny, rifling is very strong. However, as typical of milsurps the last 1/4" of barrel is quite badly damaged by typical military overcleaning using metal cleaning rods from the bore. I suspect that this is primarily whats holding back accuracy right now.

Now if this were a $1000 rifle, I would take it straight to a gunsmith to have the barrel cut/crowned without a moment's hesitation. However its a $150 beater trunk gun, and I dont wish to spend 2/3 of the cost of the rifle on having this done, or on ordering the crowning tools/pilot from Brownells. Im also on a budget right now and this is not a necessity.

There are several videos online of people facing barrels of old rifles with a mill file, and crowning it with a round head brass wood screw and lapping compound. Can this method actually be effective if done properly/patiently? Or is it doomed to failure?

If it can be done, any tips on getting it right?

Many thanks in advance for any advice :cheers:
 
On something like that, I would cut it, square it off and clean it up with a file, start the crown using a drillbit or dremel and finish it by lapping. Apply some oxpho blue or similar to protect it.

I think you know how you want to do it, you just need convincing that indeed you should.

I say go for it, it's already in poor shape, what's the worst that could happen?
 
MBP,
YES, this can be done , and quite effectively as well!! I did something similar with a Cooey single shot. With mine I cut the barrel with a hacksaw, used a file to true up the end, then used a Uni-bit or step drill to counter bore the end of the barrel. After this I used some tight fitting wooden dowel with some valve grinding compound on the end and polished up the end where the rifling ends. After all was said and done, it shoots awesome!! All this took some time but, if you don't rush it, it can be done. You'll learn something and get a real sense of accomplishment as well.
Cheers!!:)
 
thanks,
I'm quite certain I can do a good job crowning it - its the hacksaw cutting and squaring with a mill file I'm worried about. Any tips on how to do this?
I have some precision machinist's squares I can check it with.

On a Mosin M44 there is about 5/8 of muzzle sticking out beyond the front sight/bayonet sleeve that I have to work with. I cant cut beyond that because thats where my front ghost ring sight is.
I need to cut at least 1/4" of the barrel. I guess I'll just try it -- absolute worst case scenario I'm out $150 for another M44 action.
 
thats too bad the front sight is right there, a piece of paper makes a great wraparound. If you roll a piece of paper perfectly square over the muzzle you should be able to get a good straight line around the barrel to guide you. The problem is you only got 1/4" to do it. Maybe make a wraparound mark behind the sight, then measure off that to square the mark on the muzzle. You can always adjust the squareness with the file once done. Ive always wondered if crowning could be done at home
 
Yes it can be effective if done patiently. I cut a barrel and fixed the crown based on these two videos I found on youtube:

http://www.youtube.com/watch?v=b43odFm0mrI
http://www.youtube.com/watch?v=OorpZlG28fI

For the cutting part, I don't even have the dovetail cutting fixture, I just eyeballed it and proceeded very slowly in the beginning. I don't have a reamer either so I didn't bother crowning it, I just filed the muzzle and did the brass-screw-in-hand-drill trick of the second video.

The whole process took only about 15 minutes, from disassembling the gun to bluing the new muzzle.
 
Use a LEE precison case trimmer with a mandrel from the next size under in caliber, say 7mm. Wrap it with some brass shim stock or something else that is non marring and go slow. It will easily cut your bbl back nice and square. Then proceed with a lap as you had planned.
 
bad muzzle rifling

Yes, you can shorten and crown your barrel. Many barrels have simply been cut off with a hacksaw, filed reasonably square, and crowned.

Before you start, make sure you put a patch in the barrel, about 3 or 4 inches down from the muzzle. This will catch all the swarf and filings.

You can go to an auto parts store, and they have round stones mounted on a steel shank, for use in a drill. I would NOT use a drill bit to start your crown as they tend to chatter and are uneven. You can use the round stone in your drill, BUT RUN IT AT SLOW SPEED. Clamp the barrel in a vise to keep it steady. Put the grinding stone on the muzzle, and using LIGHT pressure and SLOW SPEED, gradually put your rough crown on the barrel. Do not keep the drill in one position, but "rock and rotate" the drill up, down, left and right, so that the stone wears evenly and you do not put any grooves in the crown. Then, you can use the brass round head screw and lapping compound to smooth it out.

Some of the older gunsmiths did not use a power drill, but did use a manual drill brace or hand powered drill to make the crown.

There is also another method you might look at. The Finnish Armourers were issued with a counterbore kit to enlarge the bore at the muzzle. Quite a few Mosin-Nagant rifles have been counterbored about two inches or so. Usually these rifles have a bulge in the barrel, just below the front sight. Snow got into the bore, and when the rifle was fired, the snow was an obstruction, and the barrel got bulged. A fast fix to get the rifle back into action was to counterbore the rifle bore with a reamer. I have one such rifle, and it shoots just as good as any other Mosin-Nagant that I have, even though the last 2 inches of barrel is about 9 mm size.
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juanvaldez said:
Use a LEE precison case trimmer with a mandrel from the next size under in caliber, say 7mm. Wrap it with some brass shim stock or something else that is non marring and go slow. It will easily cut your bbl back nice and square. Then proceed with a lap as you had planned.
Click to expand...

ill order a Lee case trimmer and try this - theyre only $7.
any idea where i can get brass shim stock in Canada?
cheapest ebay seller wants $25-30 shipping :eek:
 
stuff an earplug into the muzzle an inch or so to prevent any crap from the cutting, filing, and lapping from getting into your bore. when you are done push it out from the breech with a cleaning rod and clean several times, never dragging the patch back through.

It's actually surprisingly easy to do. and i would also suggest that you use either a 1/4" solid brass carriage bolt or small brass round headed screw dipped in fine or even extra fine clover brand lapping compound for the actual crowning.
 
Cut off saw. Wrap good side of barrel with a damp cold towel. cut in short burst. will make short order of removing the barrel you don't want. Leaves a very nice square end.

clean it up with a file and some emery cloth.

you can also crown using emery cloth and your thumb.

crudgery you bet but it works just fine.

I love the idea of an earplug in the bore to keep crud out of the way - learnt something new.

I am going to turn a fugly Savage 340 into a CQB camp gun - with a gentle assortment of garage gunsmithing, should be an interesting project.

Jerry
 
Dave Manson makes a nice kit for barrel crowning without a lathe ..... probably too pricey for a one time job like manbearpig's, but I thought I'd post it anyway :)

Here's the youtube video of it in action:
http://www.youtube.com/watch?v=-Xpzv1Spsnk

Here's the Manson reamers webpage with the pricing for the tool:
w w w.mansonreamers.com/PriceList.htm

The kit is ( with 2 pilots ) is listed for $295, but you can buy the components individually ( prices listed on the next page)
 
If you have a machinists square and a scribe you can mark a straight line all the way around the barrel. Then cut ahead of your line with a hack saw. File to the line with a bastard flat file then a single cut flat file. Or carefully use a disk or belt sander. (More than one way to skin a cat) depends what you have for tools and creativity. A Dremel could also do very nice work.
I used a case mouth reamer to do the crowning on my 597REM. Had a burr right from factory.
 
You don't have to cut off the barrel to do re cut a crown. There are plenty of barrels out there that are counter bored. Yes, I know, it's supposed to be done in a lathe.

Have you looked at some of those counter bore jobs on Mosins, Mas 36, 1903 Springfields? Very few of them are even close to center.

From your statement, you already have a hand drill. Chuck up a bit that is larger than the bore and drill it out. The drill will follow the bore, like a predrilled guide hole.

I've done this with more than a couple of rifles. It works well. If you want to be really fussy, chuck up a brass screw, after drilling the counter bore and use the drilled section as a guide to keep it square. Use lapping compound of course.

Out of over a dozen rifles that I've done this way, only one didn't respond to the treatment. On closer inspection, it had an extremely over size bore and was badly pitted. What have you got to lose? You're only going to drill out less than an inch and you won't have to worry about replaceing the front sight.

When it comes to crowns, unless you are planning to make a match rifle out of it, it's amazing how much lee way you have. Other than the one, the rest of the rifles done, were excellent shooters. This was a common method, utilised by many REMEs of many nations to put a rifle back into service that had a worn or rusted muzzle.
 
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