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Old January 11, 2013, 09:14 AM   #1
Crosswire3
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Barrel Re-Thread

I recently purchased a Marlin Camp 9 that had a destroyed barrel. I was able to locate a replacement barrel at a reasonable price (which is surprising since they are long out of production). Upon receiving the replacement I was met with a finer thread pitch than I was expecting. As you can see in the photo, the original barrel on the left is 20TPI and the replacement barrel is 28TPI (Thread diameter is 0.745")



I need to come up with a solution and am looking for advise/suggestions.

1) Wait around until I can locate a replacement barrel with the proper threads.

2) Cut 20TPI threads over the 28TPI threads and hope there is enough "meat" left.

3) Weld over the 28TPI threads and turn it back down, then cut 20TPI threads.

4) Save the ~10" of usable original barrel and weld on an extension to get over 16".

5) Apply for an SBR with the ~10" of usable original barrel.
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Old January 11, 2013, 12:21 PM   #2
oneoldsap
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I'd keep searching for the right barrel ! Welding isn't an option as the heated area will be annealed afterwards (soft steel) . There's no way to cut 20 TPI threads over 28 Tpi threads with out the finished product being FUBAR ! I can't see the barrel shank enough to see if it can be cut and rethreaded ! That would be the only way to use that barrel IMO .
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Old January 11, 2013, 12:26 PM   #3
Crosswire3
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Unfortunately the barrels are made right at 16", so rechambering isn't an option.
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Old January 11, 2013, 01:53 PM   #4
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Consider trying to return the barrel and get one with the correct threading.

It doesn't seem like you have many other options.
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Old January 11, 2013, 02:37 PM   #5
Crosswire3
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I was lucky enough to find this one from a forum member...there is no supply of properly threaded examples.
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Old January 11, 2013, 02:58 PM   #6
James K
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Getting a 9mm barrel should not be a problem and you have the ability to cut whatever threads you need. Of course, the price might be higher than you want to pay.

If the barrel is worn or rusted out (and not bent or cut) How about considering a barrel liner? Gun Parts Corp has 9mm barrel liners thick enough to stand that pressure, and the standard drill and reamer should work OK. Not too cheap but probably not budget busting either.

Jim
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Old January 11, 2013, 03:10 PM   #7
Crosswire3
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That's the issue...the previous owner had an underpowered round that became lodged in the barrel. He then proceeded to fire 7 rounds behind it, bursting the barrel (attached photo). Forward of this is rather rusted (probably poor storage), but the 10" behind it is fine. This "situation" makes a liner both unnecessary and unusable at the same time (due to the 16" requirement). Basically I'm stuck with this barrel (and some way of attaching it), or making a new barrel from a blank.

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Old January 11, 2013, 05:56 PM   #8
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Buy a barrel blank, have it threaded and blued.
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Old January 11, 2013, 06:32 PM   #9
Crosswire3
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Far less expensive than I was anticipating...especially since I have a lathe or 6 at my fingertips

http://www.gmriflebarrel.com/barrelb...x-125-4140-110
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Old January 11, 2013, 07:41 PM   #10
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I agree with Scorch, orrrrr it is only a 9MM. There may be enough room to turn down the shank, thread it to a smaller diameter thread, and them make a sleeve that threads onto the barrel with the correct thread on the OD of the sleeve. If you want the original stampings that is an option. It has been done before.
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Old January 11, 2013, 07:49 PM   #11
xtriggerman
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If you are handy at silver soldering, I would just cut the good shank off the barrel with about .200 worth of shoulder, bore the chamber out to about .060 worth of meat under the threads, then turn the good barrel shank n shoulder to slide right into the old shank. pre tin the new smooth shank n shoulder face, start the new shank on, heat untill you get a nice flow out, let air cool and clean it up. If properly soldered, it will be as good as if solid. Good DBL shotguns are most all silver soldered barrel shanks like this. Id do this befor I sleeve the whole barrel, but thats a nice price on a blank.
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Old January 13, 2013, 09:34 PM   #12
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I second the idea of getting a blank and turning the correct threads and chambering it properly. Don't worry about getting open sights -just put a red dot on the action. When you try to rethread a barrel and have the sight come out straight up, it complicates the operation.
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Old January 13, 2013, 10:00 PM   #13
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I can tell you a quick easy and fairly cheap way to go Crosswire.
Cut off the shank. Rethread to the correct specs and rechamber. Cut for the extractor.
Now, shank the muzzle at 5/8X24 and add a muzzle break. Pin it on and weld over the pin holes (makes it a permanent part of the barrel according to ATF.)

Done.
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Old January 19, 2013, 02:18 PM   #14
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Sure you can weld up the barrel and rethread it.
Gun barrels are not hard.
Bob Sander of Sander Custom Gun Service would TIG weld up the threads of 03A3 and recut for Mauser threads.
Seen him do it several times.

Yeah I know "you can't do that it will ruin it "
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Old January 20, 2013, 03:55 AM   #15
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He would never do it to a barrel I own.
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Old January 20, 2013, 08:16 PM   #16
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Get a blank like suggested above. You've got the lathe, no reason to screw around with trying to jury-rig the other barrel- sell it to recoup some cost.
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Old January 21, 2013, 12:21 PM   #17
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He would never do it to a barrel I own.

Well he did to many of the rifles he built and sold for years.
As he had a gross of those barrels and that is what he did.

He is a very old man now if he is still alive.
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Old January 21, 2013, 03:53 PM   #18
mikikanazawa
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Well ain't that a tough break!

Looks like all the possible options have been covered, so I'll just put in a vote.

If it were my gun, I'd make a new barrel from a blank.

Cutting the existing barrel shorter and pinning on an extension (at the muzzle end) to meet minimum length is my second choice. It would be a good opportunity to add a brake.
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Old January 22, 2013, 10:56 AM   #19
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One more option, if there's enough meat left to rethread the barrel and cut a new chamber, thread the muzzle too, mount a fixed flash hider/ muzzle break, and spot weld or silver solder it on permanently. 16" problem solved.
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Old January 23, 2013, 08:54 PM   #20
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If the minor diameters are at keast the same, you can cut 20 TPI over the 28TPI.

If the original could take 1000 foot pound of torque without stripping, the cut up on could take ~~ 500 foot pounds, and you only need 100 foot pounds.

But it would be so Mickey Mouse, I doubt you could get a real smith to do it. You would need your own lathe and a sense of humor.


Here is a 17" barrel for $35 + shipping. I have had good luck with them.
http://www.gmriflebarrel.com/barrelb...-blank,-17-x-1

I can cut 9mm chambers and throat with just a drill set.
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Old January 24, 2013, 12:40 PM   #21
Crosswire3
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I'm leaning towards trying a rethread of 20TPI over the 28TPI threads first. If it works out and I can get the final product to line up properly then it'll be great.

If that fails I will turn down the threads and weld on a 20TPI sleeve which will allow me to ensure the sights are vertical.

If both of those fail somehow I will go with a new blank.

Wish me luck.
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Old January 25, 2013, 01:53 AM   #22
Clark
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Does the old barrel have sights that have to clock straight up?

I so, you may have to take a little off the breech, the shoulder and ream out the chamber a little.
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Old January 25, 2013, 05:11 AM   #23
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Just an opinion:

As cheap and easy as it is to get a chunk of 9 mm bbl blank,you have lathes available...and you are pondering cutting threads over threads,or welding and?????

The shortest distance between two points is a straight line.You have a ruined barrel,scrap it,put a new barrel in and do it right,the first time.

IMO,if you are dealing with gunsmithing ,barreling and chambering,there is a standard to work to.You do it right!You do not know who may put their face behind your work.You take part of the face or sight from someone trying that piece and you own it.You did it.

If you want to play around and do something creative,make sights,glue wood on,add a recoil pad.That won't hurt anyone.
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Old January 25, 2013, 03:07 PM   #24
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If you just cut 20 tpi threads over the 28 tpi section, you will have very weak threads about. 013" deep. I agree with HiBC, just do it right.
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Old January 26, 2013, 08:02 PM   #25
Crosswire3
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I had a little free time today and got around to fixing the barrel. I went with the threaded sleeve which allowed me to clock the threads and align the sights with vertical. It tightened down to 200 ft-lbs and looks like it came strait from the factory...win in my book.











Since it was a loose sleeve I was able to clock the threads and align the sights with vertical. It tightened down to 200 ft-lbs and looks like it came strait from the factory...win in my book.
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