welding/gun smithing question

[dm1333]

I asked the same question over on Gun Rights Media but who knows how that will go!

I have a sporterized M1903 that groups pretty nicely but way low.  It looks like the rear bridge over the receiver was ground down before the one piece scope base was mounted.    The front of the base is screwed down, the rear was held on by a lead plug. The problem is that the base is nowhere near level.  Can that rear bridge be built up enough or have a piece of steel welded to it so that a new scope base can be screwed down both front and rear?

I know this is a question for a gun smith and I'm actually calling a good smith on Monday or Tuesday but I was also curious to see if this could be done.  I would drop the rifle off for him to look at but it is a 2 hour one way drive.  If it can't be done I may ask him if the rifle can be scout scoped.  I wasn't planning on high powered optics, I have a nice old Weaver K4 that I would like to put on the gun along with a Boyds sporter stock.  This smith is also going to mount or build a taller front sight for a Stevens bolt action .30-30 that I have.  Somebody added a rear peep which is taller than the original buckhorn sights.  And yes, it was the same amateur who worked on both rifles and I got both guns for a really good price!  No, that amateur doesn't go by dm1333 on the internet, either.  

edit: I know many people would consider a scout scope on this rifle to be blasphemy but as a left it sure makes working the bolt easier.  I'm a lefty.

[230RN]

230RN's General Rule Of Thumb ROT 745 Sec 2, ¶​3:

¶​3 Don't do any welding on the receiver or barrel of any firearm.

¶​4 Or the front end of the bolt.

¶​5 Spot-welding may be possible under some very restrictive and specialized circumstance, but refer to ¶​3.

May I assume this is a rifle with a serial number above 800,000?

Terry, 230RN

[dogmush]

Can that rear bridge be built up enough or have a piece of steel welded to it so that a new scope base can be screwed down both front and rear?

Short answer:

Yes but it'll take someone that knows what they're doing.

It can't be done with a spacer and a mechanical fastener?

[TMM]

i agree, i would never weld a firearm. way too dangerous if you end up messing up somehow (stresses, warping, removing heat treatment, etc...). i don't completely understand what you're trying to do, but i'd either shim the scope mounts, have a special block machined to screw into the mount, and mount the scope on that spacer block, or screw in something to plug the hole if you don't want to use the hole for whatever reason.

TMM

[dm1333]

The problem is that the rear bridge is too thin to screw into.  The goal of welding on the bridge is to build it back up enough that it can be tapped.  The a new scope base can be mounted.  Right now I can't mount the scope base because I destroyed the lead plug.  An oldtimer told me that back in the 40's and 50's that was a fairly common way of securing the scope base. 

Don't ask me why anybody would have ground that bridge down because on my other 1903 you can see there is plenty of material to drill and tap so the base can be screwed down.

dogmush, what kind of mechanical fastener are you talking about?

[PTK]

Are you 100% certain it's a 1903 and not a 1917? Not too many 1903s were ground down, that was the usual sporterization for the 1917 though. In any case, don't bother looking into having the receiver welded up. Without a really skilled welder, using TIG, and heat sinks, the receiver is too easy to scrap.

[dogmush]

Mechanical fastener = Screws.

If it's too ground down and you gotta weld, then PTK foreshadowed what you need.  Heat sink machined to fit tight to the sight bridge, TIG welder and someone that knows what he's doing. 

Lead's pretty easy to work.  Can you make a new plug and put it back on?

You could also try a good epoxy.  Make a metal blank of the right shape, groove the sight bridge and the bottom of the blank, put them together with a professional grade epoxy.  Then drill and tap through both the shim and the sight bridge with one hole, and screw the scope base down to both with a long screw.  Finally dress up the inside so the bolt moves freely.

[Hawkmoon]

Short answer:

Yes but it'll take someone that knows what they're doing.

It can't be done with a spacer and a mechanical fastener?

Tall scope bases are screwed to receivers. I don't see why a tall base or a base and a shim can't be screwed to the receiver.

[280plus]

http://www.jbweld.net/products/jbweld.php

[dogmush]

I'm not sure JBweld has enough adhesion for this application.

[French G.]

I'd weld it, but have to do it right. Machined brass or aluminum rod stuffed up in the front of the receiver, 350 deg templ-stik mark on the front bridge so you can see heat before it gets to affecting the temper, and a few fine TIG beads. Or stick the whole thing vertically in water with only the rear bridge sticking out and Tig it. The idea is don't send the heat to where it matters.

[230RN]

I was thinking electrical spot welding might work, which is why I added ¶​5 above.  Very local high intensity "heat," probably not enough to creep to tempered/heat treated parts.

However, I can't really picture the full problem.

I was also thinking that if one drilled a couple of, say, 1/4" holes through the part-to-be-welded-on, a TIG or MIG welder might be able to weld "upward" through the holes without transmitting too much heat to the rest of the gun.  The heated area on the gun would only be from the bottom of the 1/4" hole, as opposed to a long bead.  When the excess weldment at the top of the hole is ground off and polished, you can't hardly see there was a weld job. 

Just as much strength as you would get with screws, if not more.  Sort of like making your own rivet as you weld up through the hole. 

Sort of.

I did this once or twice on some scrap pieces just to see how it worked, and it's not as strong as a full butt weld or a lap weld, but it's at least as strong as screws and rivets.  When I got done and cleaned them up, you could not really tell they were welded together.  If you didn't know any better, you might think the two parts were epoxied together or something.


Terry, 230RN

[280plus]

I'm not sure JBweld has enough adhesion for this application.

Once applied and screwed together between the scope rail and the gun it should be held in ce by friction between the two? I thought we just needed spacing.