M1903 barrel change/rear sight base

Hello everybody my name is Paul, I live in France and I'm fond of Us Firearms.

I just bought a M1903 built in 1942. The barrel is definitely dead. So I have to change it and I have a few questions about that, in particular about the rear sight base. I purchased a brand new criterion 4 grooves barrel.

In my readings I understood that :

1) The rear sight base is maintained by two pins. One is perpendicular to the barrel preventing the base to go forward and back, and the other is parallel to the barrel preventing the base to turn.

2) I first have to unscrew and remove the old barrel with the rear sight base on it and then I can remove (try to remove) the base from the old barrel.

My problems and questions :

1) Is the barrel very hard to unscrew ? I remember of a P17 barrel in which I had to make a relief cut but on this M1903 it's impossible because of the rear sight base.

2) For the moment I can't locate the first pin. I've got an idea where it is but it's just an idea... Am I right ?

https://www.milsurps.com/images/impo...20200210-1.jpg

3) Any tip to remove the base ? Forward ? backward ? Heating ? I must save it because it will be very hard to find another one.

Thanks in advance for your answers.

'phh' - You did locate the cross-pin. Drive it Left-Side of rifle to Right.

A scrap metal piece that will fit in the sight-base, (where the 'movable-base' traverses), will give you a surface to pound on. This protects the delicate base pieces from being bent or broken. Some heat on the 'collar' can help loosen it from the barrel, before you dive it forward.

You can do this with the barrel still on the action. (The second pin will just go forward with the sight-collar. The pin may be on the right or left. In my opinion it is not necessary in a rebuild. A little Epoxy will work just as well).

1903 barrels are easier to remove than M-1917 barrels.

Good Luck on your noble project!

Ok, thank you very much. Is there a way to make this pin appear much to see better where I must pound ? Right now it seems to be part of the sight base. Sanding ?

Yes, sanding or polishing off a bit of the finish will make the beveled end of the pin a bit more visible.

Lightly center-punching the left-end of the pin will help prevent the Drive-Punch from slipping.

This will allow more force to be directed in a straight line. (You can even 'drill' slightly into the end of the pin, so your Punch is easily controlled).

Thanks , I'll try it.

One of the gunsmiths who frequents this forum ( chuckindenver ), recommends removing the barrel first. Once you have removed the transverse pin, and the front sight ( if you plan on reusing it ), remove the moveable ladder sight. Then, holding the barrel at the sight base with a good heavy leather glove, strike the muzzle of the rifle on a hard surface until the sight base comes off. Of course the barrel muzzle will be ruined in the process, and therefore should only be used when the barrel is "trashed".

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Originally Posted by phh

Ok, thank you very much. Is there a way to make this pin appear much to see better where I must pound ? Right now it seems to be part of the sight base. Sanding ?

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Yes, once you have polished the area where the pin resides, a touch of cold blue will make it show up very well. Once your barrel is off, find a scrap pipe section that is nearly the same diameter as the sight collar and turn it to the same inside diameter of the inner collar radius to drive it on.
As the collar is being driven on-you can then slightly "steer" with a twisting motion in your hand the collar to match the index marks on the receiver once it's nearly home. With the barrel installed by driving the collar right up to the face of the receiver a nice transition can be had without an unsightly line or seamless transition between the two parts.

Ok. I've localized the pin. . Tried to pound on it with a little pin remover, but for the moment nothing moves on the other side. It's gonna be a hard job...

This thing hasn't been made to be stripped.

You need to use a proper hammer and drift for this, a light tack hammer and nail won't do it. That's why most have a gunsmith do this.

Got it.

Waouh... (eureka, hourra:) )

https://www.milsurps.com/images/impo...20200211-1.jpg

Now, unscrew the barrel.... Au gunmith will do

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Originally Posted by phh

unscrew the barrel

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So, that can be done with the relief cut you mentioned, then by hand. That barrel's scrap you say. The re-barrel and head space will be a gunsmith job if you don't have the equipment. Don't know if you have lathe either...

Nice job of removing the 'sight-collar' without destroying it!