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· Registered
1,806 Posts
generally speaking, it all depends on the extent and type of the weld. Some welded DEWAT barrels have "plugs", like a bolt or a length of steel rod, etc that is stuck in the barrel and the end welded at the breech, and many others are just electric arc plug welded. Welds can be deep or superficial and the plug removed with some removal of the weld. If the mouth or wall of the chamber is compromised with pitting from the weld arc, then it will require enlargement by drilling, threading, a threaded plug installed and the plug rechambered to the orignal caliber or a new caliber. If the weld arc has not damaged the walls or chamber mouth, often the weld can be removed, and the chamber tuned to workikng condition with a rougher reamer and then finished with a finish reamer, or just with a finish reamer in the orignal caliber.
Barrels are not typically heat treated in production, but the welding often can change the structure of the metal immediately at the weld site. However, having been involved with many dozens of repairs of welded barrels, they are completely safe and functional after repair. The welds at the breech are almost always quite superficial and there is no damage to the metal integrity of the chamber as a whole. Barrels do benefit from some elasticity of the metal, so heat treatment would not contribute to the elasticity of the metal. Brittle barrels are dangeroous, and if there is any heat treatment it would be to anneal the chamber area, which reduces brittleness. In some cases hard weld has been used to close the breech, but this is unusual. Most weld on DEWAt barrels is mild steel, which will tend to crystalize at the contact area between the weld and the parent metal. When brightened or polished, it is possible to distinguish the weld material, the thin band of harder metal at the interface and then the parent metal. Annealing will reduce the brittleness of the fusion area between the weld and the parent metal.
Thousands of DEWAT MG barrels have been successfully repaired and used for many years of shooting.

Bob Naess
Black River Militaria CII

· Administrator
10,275 Posts
Agree with Bob.

In our work with "deact" (Australian) Mgs for Movie work,
we commonly come across barrels which have been Chamber welded withor without a Plug in chamber and barrel, with Muzzle Weld Plugs, and the worst of all, with cross Holes (anywhere) with or withoput welded in Pins (which may be hard or soft steel.

Condition 1. Simple chamber plug/weld: Drill/mill out, (under size to Chamber dimensions) , Punch out plug if possible. Clean up chamber with dremel tool or rough chambering reamer; Final Polish of chamber.

If Chamber eroded, or too damaged by weld flash, Bore out chamber completely, make chamber Plug from Barrel segment of same caliber, Press fit to Bored Barrel, finish off breech end, then rechamber. WE are +/- about either silver soldering Plug in place (Chilean solution) or tack welding at breech face, and then remachining barrel end.

BUT when Cross drilling of chamber has been the method, we do use the cross holes to tap for grub screws to Lock the Chamber Plug in place, and with thick barrels, overweld the screws in place (then face off by grinding or turning.)

Cross holes in the barrels are usually tapped an appropriate size, and a screw fitted( pre-profiled to match Bore) and then Over TIG welded and refinished. ( since we are Blank firing, a flush screw end inside is sufficient.)

Muzzle welding: drill out, and then Thread for BFA fitting. ( usu. 3/8x24 UNF)

Firing ball ammo:

With a Chamber sleeve, and even with Flush barrel hole screws, (no protrusion into rifling), one can fire Ball ammo...we regularly Proof all our BFA Guns once "re-built" wilt Ball ammo ( without the BFA screw, OF COURSE)

· Administrator
10,275 Posts
Agreeing with Bob (Continued)

Due to the Bouncing around of the "quick reply" window, I was unable to finish my message.

When the barrel is too badly "deacted", then the only solution is to (a) make a new barrel ( may be costly) or (b) "sleeve" the existing barrel completely (also costly, but maintains the original exterior and markings etc...) And, with most MG/LMG/SMG barrels being shorter than rifle barrels, a re-sleeve is a workable oiption. Just get a professional to do it.

WE have remade Maxim, Japanese 96 and 99 barrels, and Nambu T3/T92 barrels (change calibre to 7,62Nato as well); Bren barrels can be made, but ours had sufficient "meat" on them for a simple Chamber sleeve and re-chamber.

I speak from a purely Movie Industry perspective(Aussie), but Bob has the "On ground" Experience with NFA guns in the USA.

All, Doc AV
AV ballistics.

· Silver Bullet member
6,179 Posts
Bob is a excellent referance on any class 3 and is as honest as the day is long.
Just as well. Here in yUK a man and his son are serving two life sentences for 'un'de-watting firearms and selling them to the criminal fraternity. Thirteen murders have been linked to firearms that they 'recovered'.

Supporter of the Cape Meares Lighthouse Restoration Fund
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